Title of Invention	AN AUTOMATIC GAIN CONTROL METHOD AND AN AUTOMATIC GAIN CONTROLLER
Abstract	The invention relates to an automatic gain controller has variable gain amplifiers for variblz amplifzing the input signals and a control loop that respectivelz performs automatic gain control of these variable gain amplifiers via feedback control of the output signal level. Variation amount in the detected output of the demondulated outputs is dected in the variation amount dected in the variation amount dector. The control section selects the control and the szstem is in the stable state, and performs automatic gain control via a gain control signal in this control loop and correction gain control signals in the other control loops, and places in the non-operating state the gain control signal generator of the other control loops. Fig.1

Title of Invention

AN AUTOMATIC GAIN CONTROL METHOD AND AN AUTOMATIC GAIN CONTROLLER

Abstract

The invention relates to an automatic gain controller has variable gain amplifiers for variblz amplifzing the input signals and a control loop that respectivelz performs automatic gain control of these variable gain amplifiers via feedback control of the output signal level. Variation amount in the detected output of the demondulated outputs is dected in the variation amount dected in the variation amount dector. The control section selects the control and the szstem is in the stable state, and performs automatic gain control via a gain control signal in this control loop and correction gain control signals in the other control loops, and places in the non-operating state the gain control signal generator of the other control loops. Fig.1

Full Text	AUTOMATIC GAIN CONTROLLER AND AUTOMATIC GAIN CONTROL METHOD, AND RADIO COMMUNICATIONS APPARATUS EQUIPPED WITH AUTOMATIC GAIN CONTROL FUNCTION Background of the invention The present invention relates to automatic gain contrni that makes const&nt the output signal level via gain control using the closed loop, and in particular to an autonarig gain controller end an automatic gain control mathod wherein autoiT-atic gain concrol of a plurality or input signals is performed and to radio communications apparatus equipped with the automatic gain control function. Conventionally, in some types of signal processors, for exanple radio coirjtiunicetions apparatus, autoir.atic gain control is performed in order to make constant che variation in the signal level of a received signal caused by variation of receiving field strength in a radio propagation path such as a radio circuit and to reduce demodulation errors. As such gain control signal systems are known an open loop control signal hereby the gain of a variable gain amplifier in the subsequent: stage is controlled via an aurtomatic gain control signal generated by detecting the Level variation in an input signal, and a clcsec loop control system whereby the gain of a variable jain amplifier in the preceding stage is controlled via the automatic gair. control sianal. Fig. 11 shows an exanple of configuration cf an autorriatic gain controller according to the related ^rt applied.to rhe receiving system of radio communications apparatus. The "autonatic gain controller is composed of a variable gain ) amplifier 111, a demodulator 112, an A/D converter 113, a level detector 114, a gain control signal generator 115, and a D/A Converter 116. In the automatic gain controller according to the relatea art, a received signal.input Ri is amplified by the variable gain amplifier 111, demodulated by the demodulator 112, and converted to a digital value by the A/D converter 113, then output as a demodula-ed oucput Rd- Part of the demodulated output P.d is level-detected by the level detector 114 and captured by an automatic gain control loop, to generate an gain control signal via the gain control signal generator 115 based on the value of the demodulated output Rd. This automatic gain control signal is converted to an analoij voltage by the 0/A converter 116 and fed back to the control input end of the variable gain amplifier 111 as a gain control voltage and undergoes automatic gain control via the closed loop. In the gain ccn-rol sig;^al generator 115, the value of the demodulated output Rd (ouEput value) level-detected by the level detector 114 is averaged by an averaging section 121 for a certain lime, and the difference from a predetermined rarcet value A is calculated in a convergence difference calcuiiting auuer ^z^. in a ±oop gam control multiplier 123, the loop gain, control valu^ 3 in the automatic g5j.n contrailer is multiplied in a loop gain control multiplier 123 and se.it to .en adder iZ;. In the adder 124, the previ&us value latched by a latch circuit 125 is added to the variation amount output from the loop gain control multiplier 123 and the resulting value is sent to an operating section 126 via the latch circuit 12 5. The adder 124 and the latch circuit 125 composes an integration circuit and an integration value is latched by the Istch circuit with the tirr.ing of a latch timing centre! value D. In the operating section 126, the integrating value is converted to data corresponding to the control voltage of the variable gain am.plifier 111 and fed back to the control input end of the variable gain amplifier 111 as a gain control vol "cage. This realises automatic gain control so that the output level of the variable gain amplifier ill (output value of the level detector 114) may converge to a target value A. Some types of radio communications apparatus that performs automatic gain control as mentioned earlier have receivers oi a plurality of systems. In the related err, automatic gain ccntjroHers were provided as many as the number of receiving systems to correspond to receivers. That is, automatic gain controllers as shown in Fig. 11 wers provided as many as the number of receiving systems and auromaric gain control was individually performed In each receiver" In particular, it was necessary to provide an automatic gain controller for each receiver in order to obtain the optimum automatic gain control performance depending on the operating status in each receiving system. In radio communications apparatus according to the related art having aforementicnsd receivers cf a plurality of systems, as many automatic gain controllers as the number of receiving systems are provided. Thus, a plurality of automatic gein controllers were always operating, which causes a problem that t.he circuit scale and power consumoticn were increased. 1 Power consumption of a circuit increases in proportion to the number of systems even if the automatic gain controller is^ configured by way of software design . Even if a single automatic gain control loop was used in comnon among a plurali-y of receiving Systems in order tc reduce power consumption, it was impossible to fully correct variations in the circuit characEeristics such as che temperature characteristics and. frequency characteristics of a variable gain amplifier of each system, thus the optimum automatic gain control performance was not obtained. In particular, in an unstable system state such as "he nower en or intermitiient data reception, or in a bad receiving state, i.e., when variation in the receiving level is large or fading has taken place, high-accuracy automauic gain conurol IS required. In the configuration according to the relared art, a proper gain ccn-rol signal is not obtcined and desired automatic gain control cannon "oe perforzied. S"LLTuTLary of the Invention The invention, in view of the aforementioned circumstances, siins at providing an automatic gain controller and an automatic gain control method wherein automatic gain control of a plurality of systems can be performed depending on the operating state such as the stable/unstable signal level andpower consumption can be reduced, and to radio cornnunl cat ions apparatus equipped with the automaTic gain control function. An automatic gain controller according to the invention is a automatic gain controller having variable gain amplifiers uf a plurali-y of systems and the corresponding control loops, :oniprisinc: a gain control signal generator which generates ?, gain control signal that controls a variable gain amplifier jased on the output signal level of the variable gain amplifier; i variation amount detector which detects the variation amount if the output signal Isvel; a level comparator which compares he output signal levels of the plurality of system with each ither; an inter-ccntrol-loop correction section which ■enerates a correction gain control signal.that corrects ariations in the circuit characteristics of the other contrcl oops and that is based on a gain ccntrol signal in the control Gop where the output signal level is the highest in order to erform gain control, and an operation controller which se?$ct5 the control loop where the outpuc signal level is the highest, places gain control signal generator for the o-ther control loops in the non-operating state, and perforins gain control of the variable gc.in amplifiers of the plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in case the variation amount in the output signal level is smaller than a predetermined value. The operation controller preferably places in the operating srate the gain control signal generator for the control loops of the plurality of syste:TLS and performs gain control of the variable gain anplifier via a gain control signal in each control loop, in case the variation amount in the output signal level is larger than the predetarinined value. Preferably, the operation controller operates the gain control signal generator for each control loop in a predetermined period during system, startup from the non-operational state at power-on, to perform gain control of the variable gain arrLplifier. Or, the operation controller operates the gain control signal generator for each control loop until the variation amount: in the output signal lev__ei falls within a predeterr.ined value during system startup from the non-operational state at power-on, to perform gain control of the variable gain amplifier. Preferably, the operation controller operates theigam control signal generator for each, control loop in a predetermined period during systsm staxt\;p from the non-tiperaticnal state assumed in case intermittent operation is performed, to perform gain control of the variable aa-in a^-plifier. Or, the operation contrcller operates the gain control signal generator for each control loop unnil the variation amount in the output signal level falls within a predetermined value during sysnem startup fron the non-operational state assumed in case intermittent operation is performed, tp perform gain control of the variable gain amplifier. An automatic gain control method according to the invention is sn automatic gain control method using variable gain amplifiers of a plurality Of systems and the corresponding control loops, comprises: a gain control signal generating step for generating a gain control signal that controls a variable gain am.plifier based on the output signal level of the variable gain amplifier; a variation amount detecting step for detecting the variation amount ct the output signal level; a level comparison step for comparing the output signal levels of the plurality of system with each other; an inter-control-loop correction step for genex"bting a,correction gain control signal ^hat corrects variations in the circuit characteristics cf the circuit characteristics of the other control loops and that Is oased on a gain control signal in the control loop where :he output signal level is the highest in order to performigain control; and an, operation control s-ep for selec-ing the control loop where the output signal level is the higkesu, placing gain control a. signal generator for the other control loops in the non-operating state, and perforraing gain control of ths variable gain amplifiers of Lhe plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in case the variation aniount in the outpuc signal level is smaller than a predecermined value. The operation control step preferably places in the operating s rate the gain control signal generator for rhe control loops of the plurality of systems and performs gain control of the variable gain amplifier via a gain control signal in each control loop, in case the variation airtount in the output signal level is larger than the predetermined value. Preferably, the operation control step operates the gain control signal generator for each coni;rolloop in a predetermined period during system startup from -che non-operational state at power-on; to perform gain control of the variable gain amplifier. Or, ihe operation control step operates the gain control signal generator for each control loop until the variation air-ount in the ou-put signal level falls within a predete mined value during systera scar tup from the non-operational state at power-on, to perform cam control of the variable cain amulifier. i- Preferably, the operation control step operates the gain control signal generator for each control loop"in a predetermined period during system 5i;artup from the non-operarional sTiate assumed in case internitts."-t operation is performed, to perform gain control of the variable gain amplifier . Or, the operation control seep operates the gain control siqnal generator for each control loop until the variation amount in the ourput signal level falls within a predetermined value during system startup from the ncr_-operational state assumed in case interm.ittent operation is perforrr.ed/ to perform gain, control of the variable gain amplifier. 5.adio communications apparatus accordingto the invention :ias rsce:ivers of a plurality of systems comprising a automatic jain controller according to any of the foregoing aspects of :he ir,vention, the radio communications apparatus performing lUtomatic gain control for making constant the output signal .evel concerning a received signal via the automatic gain :ontroller. In the aforementioned configuration, a gain control .ignal is generated based on the output signal Level cf the ■ariable gain amplifier in obtaining a constant output si-gnal y Variably amplifying input signals of a plurality cf systems aspect ively via the variabis gain amplifier, and the variation mount in the output signal level is detected. In case the ariaticn amount in the output signal level is sir-aller than the predetermined valUE, the au-onatic gein, controller selects the control Loop where the output signal le-j^l is zhe highest, places gain control signal generator for the othsr control loops in the non-operating state, and performs gain connrol of the variable gain aiTiplif iers of the plurality of systems via a gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in cass the variaiiion amount in the output signal level is smaller chan a predetermined value. In case the variation amount in the output signal level is larger than the predetermined value, the automatic gain controller places in the operating state the gsin control signal generator for the control loops of the plurality of systems and performs gain control of the variable gain a.T.plif ier via a gain control signal in each control loop. in case system operation is unstable and high-accuracy gain control is required such as in a predetermined period during systeo^. startup frci?. the non-^operational state at power-on, in a predetermined period during systen startup from the non-operational state assumed in case intermittent operation is performed, and until the v£riation_amount in the outpi;t signal level falls within a predeterif.ined value during systsni startup from the non-operational state, the automatic gain controller operates the gain control signal generator for each control loop to perform gain coniroi of the variable gain aiTLpliaier. operation ccnurcl made in case cne interrr.itter.t operation 15 perioriaed is preferably applied tc a case where incerraitten-data recepuior. is perf orried in radio corjnunications apparatus. In the aforementioned steady state, assuming ths predeterminsd valua for decision of switching operation between control loops as Kl, the predetermined value for decision of switching operation at power-on, as K2, and the predetermined value for decision of switching operation in system startup in case ir:ternittsat operation is performed as K3, preferably K2 > K3 > Kl in order tc upgrade the accuracy of detecting the variation air-ount in the output signal level or operation switching control. Via the aforementioned operation control, it is possible to reduce the power consumption of a autcrr.citic gain controller while performing proper automatic gain control in a plurality of systsiTis, by placing in the non-operating state part of the circuits such as the gain control signal generator of the automatic gam controller and correcting the other control loops based on the automatic gain control signal for a control loop where the output signal level is the highest, when the output signal level is stable. 3y applying^ an automatic gain controlier and an autO-Tiatic gain control method to radio cosuTiunications apparatus, it is possible to reduce power consu!r.pT;ion while securing good receiving performance, ch-is allowing long-duration operation. Brief Description of the Draw-jngs Fig. 1 is a block diagram showing the configuration, of an automatic gain controller according to an embodi-"nent of the i invention. Fig. 2 is a block diagraiTL showing the internal configuration of a control section according to rhe first embodiment. Fig. 3 is a flowchart showing the processing procedure concerning automatic gain control according to the first eirbodiment. Fig. 4 xs a bioc>: diagram showing ths internal configuration of a control section according to che seconc embodiment. Fig. 5 is a flowchar- showing the processing procsdure concerning automatic gain control according to the second embodiment. rig. 3 is a block diagram showing the internal configuration of a control section according to the third erabodiment. Fig. 7 is a flo^wchart shewing the processing procedure concerning autonatic gain control according to the tnird embodiment. rig. 6 is a. flowchart showing the processing procedure concerning automatic gain control according "o the fourth embodiKient. Fig. 3 is a flowchart showing the processing procedure concerning autcrr.atic gain control according to the fifth embodiment. rig. 10 is a folock diagram showing the configuration of radio communications apparatus according to an enLoodiment of the invention. Fig. 11 is a block diagraxi showing an axarap] e of configuration of an automatic gain controller according to the related art applied to the receiving system of radio communications apparatus. Datailed Description of the Preferred Embodiments Embodiments of the invention will be described referring to the drawings. [First embodiment] 7ig. 1 is a clock diagranii shewing ;:he configuration of an autcma.tic gain controller according to the invention. Tig. 2 is a bloc- This embodiment shows a case where an automatic gain controller is applied to radio coruuunications apparatus having receivers of a pluraiiiiy of systems (two systems in ithis eititoodinent) used in mobile cc-Tur.unications systems such as portable telephone ssts. The automatic: gaj.n controller ha"^ automatic .jam control loops of a plurality of systems [t^i^ systems) . Hsreinafter, the control syste^n for the input signal R.I1 in rig. I is referred to as system a, and the control system for the input signal Ri2 is ref erredto as systerab. The automatic gain control is abbreviated as the AGC as required. An automai:ic gain controller has variable gain an".piif iers 11a, lib for variably amplifying the input signals ?.I1, RI2 and an AGC closed loop system (hereinafter referred to simply as the control loop) that respectively performs automatic gain control of these variable gain amplifiers 11a, lib via feeciback control of the output signal level. The automatic gain controller comprises demodulators 12a, 12b for demodula-ing the output signals of variable gain am.plifiers 11a, lib, A/D converters I3a, 13b for converting the output signals of -he demodulators 12a, 12b to digital signals and outputting the resulting signals, level detectors 14a, 14b for detac"ing the signal level of the demodulated outputs RDl, RD2 digitally converted by che A/3 converters 13a, 13b, and gain control signal generators 15a, l5b for generating gain control signals based on the outputs from the level detectors 14a, i4b. The automatic gain controller also comprises: inter-control-locp correction sections 17a, 17b for generating a correction gain control signal that corrects the other coir.trol systems and that is based on one gain control signal selecrad from among Ehs outputs of the gain concrol signal generators 15a, 15b; a variation amour.t detector 20 for detecting the variation amount in the detected output of at least one systera of the level detectors l^a, i4b, a comparator 27 for comparing between "^he deteci;ed outpucs Va, Vb of the level detector ITS, 14b; a contrcl section 19 for perfornung switching control of operation/non-operation {on/off) state of the gain control signal generators 15a, 15b che inter-control-loop correction sections l"?a, nb and a coir^parator 27, based on the variation amounts Vad, Vbd in the detected outpuL da tooted by the varia t ion amount detector 20 and the output of the comparator 27; contrcl signal selector switches Iba, l8b for switching between the output of the gain control signal generators 15a, 15b and the output of thevinter-control-locp correction section l7a, 17b; andD/A converters 15a, 16bfor converting che gain control signal or correction gain control signal output from the contrcl signal selector switches 13a> 18b to an analog signal. The int-sr-control-icop correction sections l~&, 171 generate and output a correction gain control signal containing correction of variations in the circu:.t characteristics such as the temperaturs characteristics and frequency character:.stiC5 of the other control loops tor "he gain control signals seleotac by the control signal selector switches 1?=, 18ta. The control section 19 outputs a switching contrcl signal to the coritrol signal selector switches 18a, 18b based on the comparison results in uhs comparator 27, anS makes control so that the contact S is selected for the control loop of the highest detected output level detected by the comparator 27 (hersinaf ter referred to as highest level conrrol loops} and the contact a is selected for the otiier control loops (hereinafter referred to as non-highest level control loops) . Functional configuration inside the control secrion 19 is shown in Fig. 2 . The control section 19 comprises a variation amount decision circuit 51 for determining whether the variation amount Vad vbd in the detected output detected by the variation amount detector 20 has reached a predeterminea value and a control circuit SO for generating an on/off signal for performing on/off switching of the gain control signal generator 15a, 15b-tha inter-control-loop correction sections 17o, l7b and a comparator 27, based on the decision results of the variation amount decision circuit 51 and the comparison result output cf the comparator 27, Next, Operation of the automatic gain controller according to the first embodiment will be described wich reference tc. Figs. 1-3. Input.signals ?.II, Rr2 to the systems are respectively amplified by the variable gain am.pii tiers 11a, lib, demodulated by the dem-odulators 12a, 12b, converted tc digital signals by the A/D-converters 13a, 13b, and output as demodulated outputs RDl, RD2 , The dem.odulaced outputs rlDi, RD2 are respectively detected by the level detectors I4a, 14b and the detected outputs Va, Vb are sent to the variation amount detecror 20. The variation amount detector 20 detects the variation anounts V&d, Vbd in the detected outputs Va, vb, and -he detection results are output to the control section IS as the variation amounts Vad, Vbd in the detected output. According to Fig. 3, the control section 19 compares the variation am.ounts Vad, Vbd in the detected output with a pcedeteriviined thresholdKl u^ed in the variation amount decision circuit 51 in step 511. In step 311, m case the variation amount in the input signals RIl, RI2 is small and either the variation amount Vad or vbd in the detected output is smaller than the preset threshold Kl (Vad or Vbd Next, the comparator 21 compares between the detected outputs Va, Vb of the level detectors 145, 14b in step S13. The control section 19 per forms operation switching as mentioned below when the comparison result shows that Vb is larger than Va IVa system b as tha highest level control loop and places in the ON state (operating state) the gain control signal generator 15b and ths inter-cont^roL-loop correction section 17b of system b, and sets the control signs! selector switch 18b in the contact fB position. This allovfs the gain-control signal generated by the gain control signal generator 15b to be supplied to the control input end of the variable gain amplifier lib via the D/A converter 15b and the control loop of system b undergoes the optimunn automatic gain control via this gain control signal. The control section 19 deterraines systema as a ncn-highesr level control loop and places in the OFF state (non-operating state] the gain control signal generator 15a and the inter-control-loop correction section 17a of systera a, and sets the control signal selector switch ISa in the contact a position. This allows the correction gain control signal generated by the inter-control-loop correction section 17b to be suppliea to the control input end of the variable gain amplifier lis via the D/A converter 1.6a and the control loop of system a undergoes autorr.atic gain control via this correction gain control signal, for system a as the non-highest level control loop, Che variable gain amplifier 11a is controlled by a correction gain control signal with variations in the circuit characteristics such as the teir.perature characteristics and frequency characteri-stics of the circuit of systerr. a corrected by zhe inter-control-loop correction section 17b, based om-tha gain control signal genexared by the gain control signal generator 15b of system b selected as.the hig"hest level control loop. This allows the optinaum automatic gain control to be performed. In seep S13, the control section 19 performs operation switching as mentioned below when the comparison result in step S13 shows that Va is larger than or equal to Vb (Va ^ Vb"i . That is, the control section selects system a as che highest level control loop and places in the ON state (operating state) the gain control signal generator l5a and the inter-contrcl-loop corrsction section 17a of system a, and sets the coniirol signal selector switch 19a in the contact [i position. This allows the gain control signal generated by the gain control signal generator 15a to be supplied to the control input end of zhB variable gain amplifier 11a via the D/A converter 16a and the contrcl loop of system a undergoes the optimum automatic gain control via this gain control signal- Thecon:;rol section 19 determines syscerc.b as a non-highest level control loop and places in the OFF state (non-operating stace) the gain control signal generator 15b and Che inter-control-loop correcLion section 17b of systemb, and sens rhe control signal selector switch 13b in the contact a position. This allows uhe correction gain control signal generated by che Lncer-ccr.trol-Loop correction section 17a tc be supcl-ied to the control input enc or the variable gam amplifier lib via t^e D/A converter 16h. For the cantrol loop of system, b, Che veriabls gain a^-nplifisr lib is controlled by a correction gain control signal with variations in the circuit; characteristics such as the temperature characteristics and frequency characteristics of the circuit of systen b corrected by the inter-control-ioop correction section 17a/ based on the gain contrcl signal generated by the gain control, signal generator 15a of systeiti a selected as the highest level control loop. This allows the cptimun automatic gain control to be performed- In step Sll/ in case the variation amount in the input signals RIl, R12 is large and both of the variation amount Vad and Vbd in the detected output are larger than or equal to the preset threshold Kl (Vad and Vbd 5. Kll, operation switching is made in the following way in step 516. The control section turns ON the gain control signal generators 15a, 15b and turns OFF the comparator 27 and the inter-control-loop correction sections 17a, I7b as well as sets the control signal selector switches 18a, iSb in the contact [3 position. This is for example a case where the tecsiving field strength is siaall or variation is large and the receiving state is unstable.^ In such a case, the variation arr,oL:ncs Vad, Vbd in the detected output are large . Autoraatic gain control is performed individually in aach control loop ana the opti?nuri -: torr.atic gain control is executed in each svstem. • As mentioned earlier, in che first emiDodime_it, in cass the variation amount in the detected, output"/ that is, in case Tihe input signal level is sff.all and the level is stable and automatic gain control characteristics are-nor impaired by the use of an approximate gain control signal, a control loop where the output signal level is the highest is selected and autcraatic gain control is performed using the gain control signal in the highesr-levei control loop. For the other control loops, a correction gain control signal containing correcz:ion of variations in circuit characteristics in each con-rol loop is generated based on the gam control signal to perform automatic gain control. This allows each control system to performproper automatic gain control via a gain control signal that supports variations in the circuit characteristics such as the temperature characteristics and frequency characteristics of the variable gain amplifier. In this case, operation of the gain control signal generators in the control loops other than the highest level control loop is turned OFF so than power consumption can be reduced if the control loop circuit is configured via hardware electronics. In case the control loop circuit is configured via the MPU (microprocessor unit) or DSP (digital signal processor) and operated via software programning, both the processing nime and the power cons"umption are reduced. In case automatic cam control is oarformed with the control loop where the input signal level is the highest is selected, no excessive signals are input to-the other control loops that are not selected. This avoids the disadvantage that the A/D converter ir. the subsequent stage of the variable gain amplifier is saturated. On the other hand, in case variation amount in the detected output, that is, in ca.se the input signal level is large and the level is unstable thus high-accuracy automatic gain control IS required, a gain comirol signal is generated in each control loop and automatic gain control is performed individually. This executes the opti^num high-accuracy automatic gain control in each control system. In the second to fifth einoodiiuents that follow, examples are shown where operation of the control section 19 according to the first errLbodiment is modified, since the configuration of the automatic gain controller is the same as that of the first enLOodiir.ent, the corresponding description is not given. I"Second embodir.ent] Fig. 4 is a block diagram showing the internal configuration of a control section according to the second erabodinent. ^ig- 5 is a flowchart, showing the proaesiing procedure concerning autonvatic gain control according to the second eirijodiment. The autom.atic gain controller according to rhe second enbodirient comprises, as the functional configuration o:S~the control section 19, a variation a::acunt decision circuit 51 for determining wherherihe variation/imour.t Vad,-Vt)diri the detected output has reached a predeterznined value, a tij:ier circuit 52 for counting the elapsed tiir.e from when the automatic gain controller is powered, and a control circuit 50 for performing on/off switching of the gain control signal generator 15a, 15b, the inter-control-loop correction sections 17a, IVb and a coroparator 27," based on the output of the variation amount decision circuit 51 and the timer circuit 52 as well as the comparison result output of the comparator 27. >7Gxt, operation of the automatic gain controller according to tr-e second embodiment will be described. In the second embodinent, inter-loop correction of the gain control signal is not laade but a gain, control signal is generated in each control loop to perform individual automatic gain control in the state w"nere the automatic gain controller is powered (initial state!, that is, in a certain period during systGm startup from -he non-operating state to the operating state, and control m the first embodiment is performed when the certain period has elapsed. when the automatic gain centroiJ.er is powered and started, automatic gain control is started via a gain control signal so that the presec initial valua or conversion value is approached while counting of the predetermined time tl (sec.) is soar"ed via che timer circuit 52. The concroi secnc^n 19 determxries whether the predeterained time tl (sec.) has elapsed fro:ti when the power is turned on, based on the outpu- from the timer circuit 52 ir. step 521. when the predetsrr.inad time tl (sec. ) has not yet elapsed frora when the power" Is turned on in step S21, the auoomatic gain controller places in the ON state (operating sta"e; the gain control signal generators 15a, 15b and places in the OFF state (non-operating state) the inter-control-loop correction sections 17a, i7b end the comparator 27 as well es sets the concrol signal selector switches ISa^ 18b in the contact p posinion, in step S22 . This allows each control loop to perform individual automatic gain control and proper automatic gain control is ei".ecuted in each control system. When ths predetermined time tl (sec.) has elapsed froiTi when the power is turned on, the autom.atic gain controller perfor^is automatic gain control operation in the steady state, that is, automatic gain control operation in the first embodiment in step S23 . In this case, switching is made between the control vie the gain control signal in each control loop and the control via the gain control signal in the highest level control loop and jhe correction gala control signal in the non-highest leve L control loops, depending on the raagnitude of the variation amounts Vad, Vbd in the detected output. The entire control section 19 may be configured via the M?U [microprocessor unit) or DSP (digital signal processor] and Che timer circuit 52">^^s.y be realised vi. a sofru-are timer or a hardware circuit. The timer circuit 52"is power-on reset at power-on and starts counting cime. Inthisway, in the second efnbodiirient, in a certain psriod during system startup from the ncn-operating state to the operating stabe at power-on of the automatic gain controller, that is, in an unstable state where a Large variation amoun~ in che input signal level at zhe power-on operation is expected andhigh-accuracy automatic gain control is required, selective control is not made where operation of che control loops other than the control loop that obtains the ma/?imum detected output is turned OFr to perform inter-controi-loop correction but a gain control signal is generated in each control loop in a fixed way to perfoc!^ individual automatic gain CQr.trol. This executes the optimum high-accuracy automatic gain control in each control system. [Third eiRbodiment] Fig, 6 is a block diagram showing the internal Configuration of a control section according to the third embodiment. Fig. 7 is a flowchart showing Che processing procedure concerning automatic gain control according to the third erabOGj-ment. The automatic gain controller accozdinc! zc the third embodiment comprises, as the functional configuration of the I- control section 15, a variation ancunt decision circuit 51 tor determining whether the variation amoun-Vad, Vbdinche detected output in the steady operation has reached a predetermined value, an operation start variation an^.ount decision circuit 53 for determining whether th= variation amount Vad, Vbd in the detected output at power-on operation has reached a predetermined value, and a control circuit 50 for performing on/off switching ox the gain control slgnaJ. generator 15a, 15b, the inter-control-loop correction sections l7a, l"?b and a comparator 27, based an the output of the variation amount decision circuit 51 and the operation st=rt variation amount decision circuit 53 as well as the comparison result output of the comparator 27. Next, operation of the automatic gain controller according to the third eiubodiment will be described. In the third embodiment;, inter-loop correction of the gain control signal is not made but a gain control signal is generated ::.n each control loop to perform individual automatic gain control ir. case variation amount in the detected output is large in the state where the automatic gain controller Is powered (initial state), that is, during system startup from the non-operating state to the operating state, and control in the first enitaodiaent is performed when the variation amount in the detected output has fallen within a predeter.T.ined level. When the automatic gain contro Her is powered and started, automatic gain control is started via a gain con-rol Siignal so thar the preset iniriai value or conversion value is approached and the operation start variation amoant decision circuit 53 determines whether the variation amounts Vad. Vbd have converged to a ,pr"Sds4;e"rmined level K2 (for example K2 > Kl) in step S31. In case the variation amouncs Vad, vbd in the detected output are equal to or larger than the predetermined level K2 (Vad or Vbd ^ K2) in step S3l, the automatic gain controller places in the ON state (operating state) the-gain control signal generators 15a, 15b and places in the OFF state (non-operating state) the inter-control-loop correction sections 17a, l7b and the comparator 27 as well as sets the control signal selector switches 18a/ 18i> in the contact (3 pcsiTiion, in step S32. This allows each control loop tc perform individual automatic gain control and proper automatic gain control is executed in each control syste^L. In case the variation amounts Vad, Vbd in the deuected output are smaller than the predetermined level K2 {Vad and Vbd control loops, depending on cheir.agnitude of the variation amou:;^ Vsd, Vbd in zhe detected output. Inthlsway, in the third9mbodimsn,t, during systsm startup from the ron-opf^riting state to the operating state at power-on or the automatic gain controller, that is, in an unstable state where a large variation amoant in the input signal level is expected and high-accuracy automatic gain control is required, selective control is not made where the variation amount in the detected output is determined and operation of the control loops other than ths control loop that obtains the maxiKUir. detected output is turned QzY to peirionr. inter-controi-lcop correction when the variation amount is larga, but a gain control signal is generated in each control loop in a fixed way ZQ perform individual automatic gain control. This executes the optinvJirL nigh-accuracy automatic gain control in each control system. By setting a threshold value K2 used for decision in the operation start variation amount decision circuiz 53 so that imoynt de.cision circuit 51 in the steady state of the first iEibodiiTLent (K2 > Kl) , it is possible to easily detect the "ariation a^T-ount at power-or, when the variation amouni; is renerally larger than that in the steady state. 3y combining he operation according to ths third embodiment for determining he variation amounts Vad, vbd in the detected output at power-on nd the operation according to the secondeirijodiir.ent for scaVting to count a predetermined time tl at power-on, a more minute automatic gain control at power-on. can be" performed-[ Fourth emfoodir.ent 1 Fig. S is-"a ■■f-iowdi^.art-showing tiie processing procedure concerning automatic gain control according to Lhe fourth embodimenr. The fourth embodiment is an example of the case where the automatic gain controller performs intermitrent operation . This embodiment is preferable for a case where radio communications apparatus performs intermittent reception. Since the functional configuration of the control section 19 is alrr.ost the same as Chat of the second embodiment shown in Fig. 4, the corresponding description is not given. In the fourth em}?odiment, Intsr-loop correction of the gain control signal is not made but a gain control signal is generated in each control loop to perform individual automatic gain control ar the start of each, intermittent operation, that is, in a certain period during system, starrup from the non-operating state to the operating state for intermittent operation, and control in the first embodiment is perforned when the ceri:ain period has elapsed. When "he automatic gain controller starts intermittenc operation, automatic gain control is started via a gain concrol signal so rhat the preset initial value or conversion value is approached while counting of the predetermined rime t2 (sec . ) ifor e-xamole t2 control section 19 determines whether the predetermined tirne t2 (^p-c.) has elapsed fron when ths intermittent operatic^- "-^as started, based or, the output from the timer circuit 52 in step 341. Knen thd predetermined time t2 (sec.) has riot yet elapsed from when intermittent operation was started in step 41, the automatic gain controller places in the ON state (operating state) the gain control signal generators 15a, 15b and places in the OFF state (non-operating state) the inter-concrol-loop correction sections 17a, I7b and the comparator 27 as well as sets the control signal selector switches 18a, 13b in the contact (3position, instep 34 2 . This allows each control loop ^Qperform individual automatic gain control and proper automatic gain control is executed in each control system. When the predetermined time t2 (sec.) has elapsed from when the internitten:: operation was started, the automatic gain controller performs autom.atic gain control operation in the steady state, that is, automatic gain control operation in the first embodiment in step S4. In uhis case, switching is nade between the control via the gain control signal in each control loop and the control via the gain control signal in the highest level control loop and the correcrion gain control signal in the non-highesc level control loops, depending on the magnitude of the variation amounts Vad, Vbd in the detected output. The time when the system, is unstable is generally shcrter in t!ie internittent operation tnan at power-on. By setting the timer se- value t2 for intermittent operation so tha-t t2-. is smaller than the ti~er set value tl of the tinier s-arred at power-on, it is possible to quickly shift to automatic gair-control in the steady state. In this way, in the fourth embodixenc, in a certain period during systen startup from the non-operating state to the operating stata for intarmitcent operation by the automatic gain controller, that is, in an unstable state where a large variation amount in the input signal level for incer-Tiittent operation is expected and high-accuracy automatic gain control is required, selective control is not made where operation of the control loops other than the control loop that obtains the maximum detected output is turnad OfF to perforra inter-control-loop correction but a gain control signal is generated in each control loop in a fixed way to perform individual automatic gain controi . This executes the optimu.^ high-sccuracy automatic gain control m each control system. [Fifth embodiment] Fig. 9 is a flowchart showing the processing procedure concerning automatic gam controi according to the fif^.^ , embodiment. The fifth embodiment is an example of the case "where the automatic gain ccnuroller performs intermitteni; operation. This embodiment; is preferable for a case where radio comnunicaticns apparatus performs intarmittent reception. Since the functional configuration of the control section 19 is almost the same as that of the third esabodinent shown in Fig. 5, the corresponding description is not given. In the fifth erritaodiment, inter-loop correction o^ the gsin control signal is not ir.ade but a gsin control signal is generated in e^ch control loop to perform individual automatic gain control at the start of each intermittent operation, that is, during system startup from the non-operating state to rhe operating si;ate for antermitten^ operation, and control in the first en±iodiir_ent is performed when the variation smounc in the detected output has fallen within a predetermined level. When the automatic gain controller starts intermittent operation, a^Jton-Latic gain control is started via a gain control signal so that the preset initial value or conversion value is approached and the operation start variation amount decision circuit 53 determines whether the variation amounts Vad, Vod have converged to a predetermined level K3 (for exanple K3 > Kl) in step S51. In case the variation amounts Vad, Vt>d in the detected output are equal to or larger than the predetermined level K3 (Vad or Vbd ^ K3) in step 351, the automatic gain controller places in the OX state (operating state) the gain control signal generators 15a, 15b and places in the OFF state (non-operating state) the inter-control-loop correction sections 17a, 17b and the comparator 27 as well as sets the control signal selkector switches 18a, leb in the contact (3 position, in step S52. This ailcws sach control loop to perform individual autcm-atic gain control and proper automatic gain control is executed in each control sys"ett.. - In cas^e the variation aniounts Vad, Vbd in the detected output ere smaller than the prsdetermined level K3 (Vsd and Vbd Inthisway, in the fifth erobodiraent, duringsysterr-startup fro.Ti the non-operating state to the operating state for interrr.ittent operation by the automatic gain controller, that is, in an unstable state where a large variation amount in the input signal level is expected and high-accuracy eutomstic gain control is recuired, selective control is not made where the variation amount in the detected output is determined and operation of the control loops other than the control loop that obtains the m3>;imun". detected output i^ turned OFF to perform inter-con-rol-loop correction when the variation amouRt is large, but a gain, control signal is generated in each control loop in a fixed way to perform, individual automatic gain control. This executes the optimuzr. high-accuracy automatic gain control in each control system. By setting a threshold value K2 used for decision in the operation start variation ain.ount decision circuit 53 so that K3 is larger than the threshold value Kl used in the variation amount decision circuit 51 in the steady state of the first e-Tibodiment and : Fig- IC is a block diagram showing the configuration or :=dio corrjr.ur.ications apparatus according to an embodiment of ",he invention. Tha sixth embodiraent shovv^s an examnlfe" of configuration of radio corjnunications apparatus equipped wich an automatic gain controllar according to the aforen;entioni=d :first through fifth emijodiments. the radio cormnunications apparatus is composed of receivers of aplurality of systems (two systems in this ex^i^plel . The radio communications apparatus comprises antennas 71s, lib, an antenna multiplexer 72, bar.d-pass filter (BPTj used in the RF band (radio frequency band) 73a, 73b, low-noise aziplifiars 74a, 74b, down-mixers for frequency-converting signals in the KT band to signals in the IF [interrriediate frequency) band, band-pass filters (EPr"s) 763, 76b used in the IF band, an autorr.atic gain control circuit (AGC) 77, a frequency synthesizer 78, a receiver (RFC) 79 for outputting received signals in the form of voice data, a transceiver controller 80 for perfarming control of each section, a transmitter circuit 31 for processing send signals, a key input section [KEY) 82 for performing a variety of operations, amicrophone (MIC) 83 for inputting \"oice data as a send signal, and a battery (BATT) 84 for supplying power to each section. The automatic gain control circuit 77 formed control loops at the receivers of the systems used, as shown in the first embodiment in Fig. 1. Operation of the radio communications apparatus will be described. When radio signals (assume for example signals in the 2-GHz band) are received via antennas 7ia, 7ib, the receivec signals cass throuah the antenna multiplexer 72 and signal I- coraponents in a predetermined band are attenuated by the band-pass filters "3a, 73b and signal compgnents in a desired frequency band are respectively pass through the filters and output. The received signals that passed throi:gh the band-pass filters V3a, 73b are respectively arr.pli^ied by the low~noise amplifiers 74a, 74b and frequency-converted by to signals in the IF band (for example 330 [MHz] band) by the down.-tTiiy.ers 75a, 75b, then input to the automatic gain control circuit 77 via the band-pass filters "^69, 76b, iri one system The received signals are demodulated by a demodulator provided in the automatic gain, con-crol circuit 77 aad output to the transceiver controller 80 as baseband signals anduridergo signal processing, "n this practice, processing explained in the aforem.entioned first through fifth embodinients is performed in the control loops of the systems in the aiitoiri.atic gain concrol circuit 77 . A generated gain control signal or correction gain control signal is supplied to a variable gain amplifisr for preferable automatic gain control. In case the receiving field strength is stable and variation in the received signal level is small thus receiving characteristics are not impaired by the use of an approximate gain control signal, a control loop where the output signal level is The highest is selected and auromatic gain control is performed using the gain control signal ir. the highest-level control loop. For the other control loops, a correctiomgain control signal containing correction of variations in circuit characteristics in each central loop is generated based on the gain control signal to perform automatic gain control. This allows each control system to perform proper automatic gain control via a gain control signal that supports variations in the circuit characteristics such as the temperature characteristics and frequency characteristics of the variable gain ampllfiej:. In this case, operation of th.§ gain control signal generators in the control loops other than rhe highest level control loop is turned OFF so that power cons"omption can be reduced. In this case, control is always raade by selecting a control loop where the received signal level is the highest, no excessive signals are input to the other control loops that are not selected, This avoids the disadvantage that the A/E converter in the subsequent stage of the variable gain ajnplif ier is saturated. On the other hand, in case the receiving field strength is unstable and the variation in the received signal level is large and high-accuracy automatic gain control is required, ;uch as when the receiving environment has changed and signal iropagacion is deteriorated with fading taking place, ndividual automatic gain control is perforn:ied via a gain control ignal in each control loop. This executes the optiir.um igh-accuracy autorriatic gam control in each control systera nd provides operation foCvising on the receiving performance. thereby obtaining a preferatola received signal. In case a large variation in the received signal level is expected andhigh-accuracy automatic gain control is required during system startup at power-^on^ Individual automatic gain control is performed via a gain control signal in each control Loop, without selecting the highest level control loop or correcting a gain control signal in a certain period from power-on as in the second eirLbodimerit, or until the variation amount in the detected output converges within a predetermined value as in che third enibcdiKient. This executes the octiraum high-accuracy automatic gain ccn-croi in each control system and provides operation focusing on the receiving performance, thereby obtaining a preferable received signal. In case a variation ir. the received signal level is large and high-accuracy automatic gain control is required during system startup when each intermittent operation is started, ir\di vidua! automatic gain control is per formed via a gain control signal in each control loop, without selecting the highest level control loop or correcting a gain control signal in a certain period from power-on as in the fourth embodiment, or until the varia-ion amount in the detected output converges within a prederermined value as in the fifth embodiment. This also executes the optimum hii^h^accuracy automatic gain control In each control system and.provides operation focusing on the receiving performance, thereby obtaining a preferable received signal As mentioned earlier, accordir.g to tne invention, it is possiiDle tc execute automatic gain control of a plurality of systems depending on the operating state such/as stable/unstable signal level and to obtain proper automatic gain control performance in each system as well as to reduce power consumption. WHAT IS CLAIMED IS: 1. An automatic gain controller having variable gain amplifiers of a plursality of systems and ths corresponding control loops, comprising: a gain control signal generator which generates a gain control signal that controls a variable gain amplifier based on the output signal level of the variable gain amplifier; a variation amount detector which detects the variation amount of the output signal level; am level comparator which compates the output signal levels of the plurality of system with each other; ^ a inter-control-loop correction section which generates a. correction gain control signal that corrects variations in the circuit characteristics of the other control loops and that is based on a gain control signal in the control loop where the output signal level is the highest in order to perform gain control; and a operation ,controller which selects the control Icop where ths output signal level is the highest, places the gain/ gontrol signal generator for the other control loops in the non-operating state, and performs gain control of the variable gain amplifiers of the plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, xn case the variation amount in the output signal level is smaller than a predetermined value. 2. Ar. automatic gain controller according to claim 1, wherein the operation ccntroller places in the operating state the gain concrol signal generator for the control loops of the pluralicy of systems and performs gain control of the ," r variable gain am.plif ier via a gain control signal in each control loop, in case the variation amount in the output signal level is larger than the predetermined value. 3. An automatic gain controller according to claim 7, wherein the operation controller operates the gain control signal generator for each control loop in a preaetermined period during system startup from the non-operational state at power-on, to perform gem control of the variable gain amplifier. 4. An automatic gain controller according to claim. 1, wherein the operation controller operates the gain control signal generator for each control loop until the variation amount in the output signal level falls within a predetermined vaiue during system startup from the non-operational state ac power-on, to perform, gain control of the variable gain amplifier. Ar_ autor.atic gain controller according to cLaim 1, wherein the Ciperatior. controller operates the gain control signal generator for each control loop in a predeterminedperiod during systsra startup frorTi the non-operational state in case intermittent operation Js performed, to perforin gain control" r ot the variable gain amplifier. V 5. An automatic gain controller according to claim "L, whersin the operatian controller operates the gain control signal generator for each control loop until the variation amount in the catput signal level falls within a predetermined value during sysrex startup frciTi the non-operational state in case intermittent operaticn is performed, to perform gain control/ of Che variable gam amplifier. 7, An automatic gaia control raethod using variable gain amplifiers of a plurality of systems and the corresponding control loops,,, coniprising: a gain control signal generating step for generating a gain control signal that control a variable gain amplifier based on the output signal level of the variable gain aniplifier; a variation amount detecting step for. detecting the variation amount of the output signal; a level comparison step for comparing the output signali levels cr the plurality of system with each other; an inter-control-locp correction step for generating a correction gain control signal that corrects variations in the circuit cheracterisrics of the other control loops and thac is basse on a gain control signal in the control loop where the output signal level is the highest in order to perform gain control; and an operation control step for selecting the control loop where the output signal level is the highest, placing a gain control signal generator for the other control loops in the non-opera ting state, and per forming gein control of the variatble gain amplifiers of the plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in case the variation amount in the output signal Level is smaller than a predetermined value. 6 . An automatic gain control method according to claim 7, wherein the operation control step places in the operating State Che gain control signal generator for the control loops of the plurality of systems and performs gain control of the variable gain amplifier via a gain control signal in each control oop, in case the variation amount in the output signal level 5 larger than the predacermined value. 9 . An automatic gain control method according to claim , wherein the operation control step operates the gam control signal generator for each control loop in a predetermined period during system startup from the non-operational state at power-on to perform gain control of the variable gain anplifier. 10. An autonatic gain control method according to claim. 7, wherein the operation control step operates the gain control signal generator for each control loop until the variation amount in the output signal level falls within a predetermined value during system 3-artup from the non-operational statear power-on, to perform gain control of the variable gain amplifier. 1l. An automatic gain control method according to claim 7, wherein ths operation control step operates the gain control signal generator for each control loop in a predetermined period during systsn startup from the non-operational state in case intermittent operation is performed, to perform gain control of the variable gain amplifier. 12 . An automatic gain control method according to claim 7, wherein the operation control step operates the gain control signal generator for each control loop until the variation amount in the output signal level fails within a predeter."nined value during systerr. startup from the non-operational state in case intermittent operation is performed, to perform gain control of the variable gain amplifier. 13. A Radio cominunications apparatus having receivers of a plurality of systems comprising an automatic gain controller which includes: a gain control, signal generator which generares a gain control signal that controls a variaole gain err.plifier based on the output signal level of the variable gain amplifier; a variation aimount deteccor which detects the variation amount of the output signal level; a level comparator which compares the output signal levels of the pluraliity of system with each other; a inter-control-loop correction section which generates a correction gain control signal that corrects variations in the circuit characteristics of the other control loops and that is based on a gain control signal in the control loop where the output signal level is the highest in order to perform gain control; and a operation controller which selects the control loop where the output signal level is the highest, places the gain control signal generator for the other control loops in the non-operatir.g state, end performs gain control of the variable gain amplitiers of the plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in case the variation ancunt in the output signal level is smaller than a predetermined value. 14. . A automatic gain controller substantially as herein described with reference to the accompanying drawings. (0} A radio communications apparatus substaotially as herein described with i reference to the accompanying drawings.

Full Text

AUTOMATIC GAIN CONTROLLER AND AUTOMATIC GAIN CONTROL METHOD,
AND RADIO COMMUNICATIONS APPARATUS
EQUIPPED WITH AUTOMATIC GAIN CONTROL FUNCTION
Background of the invention
The present invention relates to automatic gain contrni that makes const&nt the output signal level via gain control using the closed loop, and in particular to an autonarig gain controller end an automatic gain control mathod wherein autoiT-atic gain concrol of a plurality or input signals is performed and to radio communications apparatus equipped with the automatic gain control function.
Conventionally, in some types of signal processors, for exanple radio coirjtiunicetions apparatus, autoir.atic gain control is performed in order to make constant che variation in the signal level of a received signal caused by variation of receiving field strength in a radio propagation path such as a radio circuit and to reduce demodulation errors. As such gain control signal systems are known an open loop control signal hereby the gain of a variable gain amplifier in the subsequent: stage is controlled via an aurtomatic gain control signal generated by detecting the Level variation in an input signal, and a clcsec loop control system whereby the gain of a variable jain amplifier in the preceding stage is controlled via the automatic gair. control sianal.

Fig. 11 shows an exanple of configuration cf an autorriatic gain controller according to the related ^rt applied.to rhe receiving system of radio communications apparatus. The "autonatic gain controller is composed of a variable gain ) amplifier 111, a demodulator 112, an A/D converter 113, a level detector 114, a gain control signal generator 115, and a D/A Converter 116.
In the automatic gain controller according to the relatea art, a received signal.input Ri is amplified by the variable gain amplifier 111, demodulated by the demodulator 112, and converted to a digital value by the A/D converter 113, then output as a demodula-ed oucput Rd- Part of the demodulated output P.d is level-detected by the level detector 114 and captured by an automatic gain control loop, to generate an gain control signal via the gain control signal generator 115 based on the value of the demodulated output Rd. This automatic gain control signal is converted to an analoij voltage by the 0/A converter 116 and fed back to the control input end of the variable gain amplifier 111 as a gain control voltage and undergoes automatic gain control via the closed loop.
In the gain ccn-rol sig;^al generator 115, the value of the demodulated output Rd (ouEput value) level-detected by the level detector 114 is averaged by an averaging section 121 for a certain lime, and the difference from a predetermined rarcet value A is calculated in a convergence difference calcuiiting

auuer ^z^. in a ±oop gam control multiplier 123, the loop gain, control valu^ 3 in the automatic g5j.n contrailer is multiplied in a loop gain control multiplier 123 and se.it to .en adder iZ*;. In the adder 124, the previ&us value latched by a latch circuit 125 is added to the variation amount output from the loop gain control multiplier 123 and the resulting value is sent to an operating section 126 via the latch circuit 12 5. The adder 124 and the latch circuit 125 composes an integration circuit and an integration value is latched by the Istch circuit with the tirr.ing of a latch timing centre! value D. In the operating section 126, the integrating value is converted to data corresponding to the control voltage of the variable gain am.plifier 111 and fed back to the control input end of the variable gain amplifier 111 as a gain control vol "cage. This realises automatic gain control so that the output level of the variable gain amplifier ill (output value of the level detector 114) may converge to a target value A.
Some types of radio communications apparatus that performs automatic gain control as mentioned earlier have receivers oi a plurality of systems. In the related err, automatic gain ccntjroHers were provided as many as the number of receiving systems to correspond to receivers. That is, automatic gain controllers as shown in Fig. 11 wers provided as many as the number of receiving systems and auromaric gain control was individually performed In each receiver*" In

particular, it was necessary to provide an automatic gain controller for each receiver in order to obtain the optimum automatic gain control performance depending on the operating status in each receiving system.
In radio communications apparatus according to the related art having aforementicnsd receivers cf a plurality of systems, as many automatic gain controllers as the number of receiving systems are provided. Thus, a plurality of automatic gein controllers were always operating, which causes a problem that t.he circuit scale and power consumoticn were increased.
1
Power consumption of a circuit increases in proportion to the number of systems even if the automatic gain controller is^ configured by way of software design . Even if a single automatic gain control loop was used in comnon among a plurali-y of receiving Systems in order tc reduce power consumption, it was impossible to fully correct variations in the circuit characEeristics such as che temperature characteristics and. frequency characteristics of a variable gain amplifier of each system, thus the optimum automatic gain control performance was not obtained. In particular, in an unstable system state such as "he nower en or intermitiient data reception, or in a bad receiving state, i.e., when variation in the receiving level is large or fading has taken place, high-accuracy automauic gain conurol IS required. In the configuration according to the relared art, a proper gain ccn-rol signal is not obtc*ined

and desired automatic gain control cannon "oe perforzied.
S"LLTuTLary of the Invention
The invention, in view of the aforementioned
circumstances, siins at providing an automatic gain controller
and an automatic gain control method wherein automatic gain
control of a plurality of systems can be performed depending
on the operating state such as the stable/unstable signal level
andpower consumption can be reduced, and to radio cornnunl cat ions
apparatus equipped with the automaTic gain control function.
An automatic gain controller according to the invention
is a automatic gain controller having variable gain amplifiers
uf a plurali-y of systems and the corresponding control loops,
:oniprisinc: a gain control signal generator which generates
?, gain control signal that controls a variable gain amplifier
jased on the output signal level of the variable gain amplifier;
i variation amount detector which detects the variation amount
if the output signal Isvel; a level comparator which compares
he output signal levels of the plurality of system with each
ither; an inter-ccntrol-loop correction section which
■enerates a correction gain control signal.that corrects
ariations in the circuit characteristics of the other contrcl
oops and that is based on a gain ccntrol signal in the control
Gop where the output signal level is the highest in order to
erform gain control, and an operation controller which se?$ct5

the control loop where the outpuc signal level is the highest,
places gain control signal generator for the o-ther control loops in the non-operating state, and perforins gain control of the variable gc.in amplifiers of the plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in case the variation amount in the output signal level is smaller than a predetermined value.
The operation controller preferably places in the operating srate the gain control signal generator for the control loops of the plurality of syste:TLS and performs gain control of the variable gain anplifier via a gain control signal in each control loop, in case the variation amount in the output signal level is larger than the predetarinined value.
Preferably, the operation controller operates the gain control signal generator for each control loop in a predetermined period during system, startup from the non-operational state at power-on, to perform gain control of the variable gain arrLplifier. Or, the operation controller operates the gain control signal generator for each control loop until the variation amount: in the output signal lev__ei falls within a predeterr.ined value during system startup from the non-operational state at power-on, to perform gain control of the variable gain amplifier.
Preferably, the operation controller operates theigam

control signal generator for each, control loop in a predetermined period during systsm staxt\;p from the non-tiperaticnal state assumed in case intermittent operation is performed, to perform gain control of the variable aa-in a^-plifier. Or, the operation contrcller operates the gain control signal generator for each control loop unnil the variation amount in the output signal level falls within a predetermined value during sysnem startup fron the non-operational state assumed in case intermittent operation is performed, tp perform gain control of the variable gain amplifier.
An automatic gain control method according to the invention is sn automatic gain control method using variable gain amplifiers of a plurality Of systems and the corresponding control loops, comprises: a gain control signal generating step for generating a gain control signal that controls a variable gain am.plifier based on the output signal level of the variable gain amplifier; a variation amount detecting step for detecting the variation amount ct the output signal level; a level comparison step for comparing the output signal levels of the plurality of system with each other; an inter-control-loop correction step for genex"bting a,correction gain control signal ^hat corrects variations in the circuit characteristics cf the circuit characteristics of the other control loops and that Is oased on a gain control signal in the control loop where :he output signal level is the highest in order to performigain

control; and an, operation control s-ep for selec-ing the control loop where the output signal level is the higkesu, placing gain control a. signal generator for the other control loops in the non-operating state, and perforraing gain control of ths variable gain amplifiers of Lhe plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in case the variation aniount in the outpuc signal level is smaller than a predecermined value.
The operation control step preferably places in the operating s rate the gain control signal generator for rhe control loops of the plurality of systems and performs gain control of the variable gain amplifier via a gain control signal in each control loop, in case the variation airtount in the output signal level is larger than the predetermined value.
Preferably, the operation control step operates the gain
control signal generator for each coni;rolloop in a predetermined
period during system startup from -che non-operational state
at power-on; to perform gain control of the variable gain
amplifier. Or, ihe operation control step operates the gain
control signal generator for each control loop until the
variation air-ount in the ou-put signal level falls within a
predete mined value during systera scar tup from the
non-operational state at power-on, to perform cam control of
the variable cain amulifier. i-

Preferably, the operation control step operates the gain control signal generator for each control loop"in a predetermined period during system 5i;artup from the non-operarional sTiate assumed in case internitts."-t operation is performed, to perform gain control of the variable gain amplifier . Or, the operation control seep operates the gain control siqnal generator for each control loop until the variation amount in the ourput signal level falls within a predetermined value during system startup from the ncr_-operational state assumed in case interm.ittent operation is perforrr.ed/ to perform gain, control of the variable gain amplifier.
5.adio communications apparatus accordingto the invention :ias rsce:ivers of a plurality of systems comprising a automatic jain controller according to any of the foregoing aspects of :he ir,vention, the radio communications apparatus performing lUtomatic gain control for making constant the output signal .evel concerning a received signal via the automatic gain :ontroller.
In the aforementioned configuration, a gain control .ignal is generated based on the output signal Level cf the ■ariable gain amplifier in obtaining a constant output si-gnal y Variably amplifying input signals of a plurality cf systems aspect ively via the variabis gain amplifier, and the variation mount in the output signal level is detected. In case the ariaticn amount in the output signal level is sir-aller than

the predetermined valUE, the au-onatic gein, controller selects the control Loop where the output signal le-j^l is zhe highest, places gain control signal generator for the othsr control loops in the non-operating state, and performs gain connrol of the variable gain aiTiplif iers of the plurality of systems via a gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in cass the variaiiion amount in the output signal level is smaller chan a predetermined value. In case the variation amount in the output signal level is larger than the predetermined value, the automatic gain controller places in the operating state the gsin control signal generator for the control loops of the plurality of systems and performs gain control of the variable gain a.T.plif ier via a gain control signal in each control loop.
in case system operation is unstable and high-accuracy gain control is required such as in a predetermined period during systeo^. startup frci?. the non-^operational state at power-on, in a predetermined period during systen startup from the non-operational state assumed in case intermittent operation is performed, and until the v£riation_amount in the outpi;t signal level falls within a predeterif.ined value during systsni startup from the non-operational state, the automatic gain controller operates the gain control signal generator for each control loop to perform gain coniroi of the variable gain aiTLpliaier.

operation ccnurcl made in case cne interrr.itter.t operation 15 perioriaed is preferably applied tc a case where incerraitten-data recepuior. is perf orried in radio corjnunications apparatus.
In the aforementioned steady state, assuming ths predeterminsd valua for decision of switching operation between control loops as Kl, the predetermined value for decision of switching operation at power-on, as K2, and the predetermined value for decision of switching operation in system startup in case ir:ternittsat operation is performed as K3, preferably K2 > K3 > Kl in order tc upgrade the accuracy of detecting the variation air-ount in the output signal level or operation switching control.
Via the aforementioned operation control, it is possible to reduce the power consumption of a autcrr.citic gain controller while performing proper automatic gain control in a plurality of systsiTis, by placing in the non-operating state part of the circuits such as the gain control signal generator of the automatic gam controller and correcting the other control loops based on the automatic gain control signal for a control loop where the output signal level is the highest, when the output signal level is stable. 3y applying^ an automatic gain controlier and an autO-Tiatic gain control method to radio cosuTiunications apparatus, it is possible to reduce power consu!r.pT;ion while securing good receiving performance, ch-is allowing long-duration operation.

Brief Description of the Draw-jngs
Fig. 1 is a block diagram showing the configuration, of an automatic gain controller according to an embodi-"nent of the i invention.
Fig. 2 is a block diagraiTL showing the internal configuration of a control section according to rhe first embodiment.
Fig. 3 is a flowchart showing the processing procedure concerning automatic gain control according to the first eirbodiment.
Fig. 4 xs a bioc>: diagram showing ths internal configuration of a control section according to che seconc embodiment.
Fig. 5 is a flowchar- showing the processing procsdure concerning automatic gain control according to the second embodiment.
rig. 3 is a block diagram showing the internal configuration of a control section according to the third erabodiment.
Fig. 7 is a flo^wchart shewing the processing procedure concerning autonatic gain control according to the tnird embodiment.
rig. 6 is a. flowchart showing the processing procedure concerning automatic gain control according "o the fourth

embodiKient.
Fig. 3 is a flowchart showing the processing procedure concerning autcrr.atic gain control according to the fifth embodiment.
rig. 10 is a folock diagram showing the configuration of radio communications apparatus according to an enLoodiment of the invention.
Fig. 11 is a block diagraxi showing an axarap] e of configuration of an automatic gain controller according to the related art applied to the receiving system of radio communications apparatus.
Datailed Description of the Preferred Embodiments Embodiments of the invention will be described referring to the drawings. [First embodiment]
7ig. 1 is a clock diagranii shewing ;:he configuration of an autcma.tic gain controller according to the invention. Tig. 2 is a bloc- This embodiment shows a case where an automatic gain controller is applied to radio coruuunications apparatus having receivers of a pluraiiiiy of systems (two systems in ithis

eititoodinent) used in mobile cc-Tur.unications systems such as portable telephone ssts. The automatic: gaj.n controller ha"^ automatic .jam control loops of a plurality of systems [t^i^ systems) . Hsreinafter, the control syste^n for the input signal R.I1 in rig. I is referred to as system a, and the control system for the input signal Ri2 is ref erredto as systerab. The automatic gain control is abbreviated as the AGC as required.
An automai:ic gain controller has variable gain an".piif iers 11a, lib for variably amplifying the input signals ?.I1, RI2 and an AGC closed loop system (hereinafter referred to simply as the control loop) that respectively performs automatic gain control of these variable gain amplifiers 11a, lib via feeciback control of the output signal level. The automatic gain controller comprises demodulators 12a, 12b for demodula-ing the output signals of variable gain am.plifiers 11a, lib, A/D converters I3a, 13b for converting the output signals of -he demodulators 12a, 12b to digital signals and outputting the resulting signals, level detectors 14a, 14b for detac"ing the signal level of the demodulated outputs RDl, RD2 digitally converted by che A/3 converters 13a, 13b, and gain control signal generators 15a, l5b for generating gain control signals based on the outputs from the level detectors 14a, i4b.
The automatic gain controller also comprises: inter-control-locp correction sections 17a, 17b for generating a correction gain control signal that corrects the other coir.trol

systems and that is based on one gain control signal selecrad from among Ehs outputs of the gain concrol signal generators 15a, 15b; a variation amour.t detector 20 for detecting the variation amount in the detected output of at least one systera of the level detectors l^a, i4b, a comparator 27 for comparing between "^he deteci;ed outpucs Va, Vb of the level detector ITS, 14b; a contrcl section 19 for perfornung switching control of operation/non-operation {on/off) state of the gain control signal generators 15a, 15b che inter-control-loop correction sections l"?a, nb and a coir^parator 27, based on the variation amounts Vad, Vbd in the detected outpuL da tooted by the varia t ion amount detector 20 and the output of the comparator 27; contrcl signal selector switches Iba, l8b for switching between the output of the gain control signal generators 15a, 15b and the output of thevinter-control-locp correction section l7a, 17b; andD/A converters 15a, 16bfor converting che gain control signal or correction gain control signal output from the contrcl signal selector switches 13a> 18b to an analog signal.
The int-sr-control-icop correction sections l~&, 171 generate and output a correction gain control signal containing correction of variations in the circu:.t characteristics such as the temperaturs characteristics and frequency character:.stiC5 of the other control loops tor "he gain control signals seleotac by the control signal selector switches 1?=, 18ta. The control section 19 outputs a switching contrcl signal

to the coritrol signal selector switches 18a, 18b based on the comparison results in uhs comparator 27, anS makes control so that the contact S is selected for the control loop of the highest detected output level detected by the comparator 27 (hersinaf ter referred to as highest level conrrol loops} and the contact a is selected for the otiier control loops (hereinafter referred to as non-highest level control loops) .
Functional configuration inside the control secrion 19 is shown in Fig. 2 . The control section 19 comprises a variation amount decision circuit 51 for determining whether the variation amount Vad* vbd in the detected output detected by the variation amount detector 20 has reached a predeterminea value and a control circuit SO for generating an on/off signal for performing on/off switching of the gain control signal generator 15a, 15b-tha inter-control-loop correction sections 17o, l7b and a comparator 27, based on the decision results of the variation amount decision circuit 51 and the comparison result output cf the comparator 27,
Next, Operation of the automatic gain controller according to the first embodiment will be described wich reference tc. Figs. 1-3. Input.signals ?.II, Rr2 to the systems are respectively amplified by the variable gain am.pii tiers 11a, lib, demodulated by the dem-odulators 12a, 12b, converted tc digital signals by the A/D-converters 13a, 13b, and output as demodulated outputs RDl, RD2 , The dem.odulaced outputs rlDi,

RD2 are respectively detected by the level detectors I4a, 14b and the detected outputs Va, Vb are sent to the variation amount detecror 20. The variation amount detector 20 detects the variation anounts V&d, Vbd in the detected outputs Va, vb, and -he detection results are output to the control section IS as the variation amounts Vad, Vbd in the detected output.
According to Fig. 3, the control section 19 compares the variation am.ounts Vad, Vbd in the detected output with a pcedeteriviined thresholdKl u^ed in the variation amount decision circuit 51 in step 511. In step 311, m case the variation amount in the input signals RIl, RI2 is small and either the variation amount Vad or vbd in the detected output is smaller than the preset threshold Kl (Vad or Vbd Next, the comparator 21 compares between the detected outputs Va, Vb of the level detectors 145, 14b in step S13. The control section 19 per forms operation switching as mentioned below when the comparison result shows that Vb is larger than Va IVa
system b as tha highest level control loop and places in the ON state (operating state) the gain control signal generator 15b and ths inter-cont^roL-loop correction section 17b of system b, and sets the control signs! selector switch 18b in the contact fB position. This allovfs the gain-control signal generated by the gain control signal generator 15b to be supplied to the control input end of the variable gain amplifier lib via the D/A converter 15b and the control loop of system b undergoes the optimunn automatic gain control via this gain control signal. The control section 19 deterraines systema as a ncn-highesr level control loop and places in the OFF state (non-operating state] the gain control signal generator 15a and the inter-control-loop correction section 17a of systera a, and sets the control signal selector switch ISa in the contact a position. This allows the correction gain control signal generated by the inter-control-loop correction section 17b to be suppliea to the control input end of the variable gain amplifier lis via the D/A converter 1.6a and the control loop of system a undergoes autorr.atic gain control via this correction gain control signal, for system a as the non-highest level control loop, Che variable gain amplifier 11a is controlled by a correction gain control signal with variations in the circuit characteristics such as the teir.perature characteristics and frequency characteri-stics of the circuit of systerr. a corrected by zhe inter-control-loop correction section 17b, based om-tha

gain control signal genexared by the gain control signal generator 15b of system b selected as.the hig"hest level control loop. This allows the optinaum automatic gain control to be performed.
In seep S13, the control section 19 performs operation switching as mentioned below when the comparison result in step S13 shows that Va is larger than or equal to Vb (Va ^ Vb"i . That is, the control section selects system a as che highest level control loop and places in the ON state (operating state) the gain control signal generator l5a and the inter-contrcl-loop corrsction section 17a of system a, and sets the coniirol signal selector switch 19a in the contact [i position. This allows the gain control signal generated by the gain control signal generator 15a to be supplied to the control input end of zhB variable gain amplifier 11a via the D/A converter 16a and the contrcl loop of system a undergoes the optimum automatic gain control via this gain control signal-
Thecon:;rol section 19 determines syscerc.b as a non-highest level control loop and places in the OFF state (non-operating stace) the gain control signal generator 15b and Che inter-control-loop correcLion section 17b of systemb, and sens rhe control signal selector switch 13b in the contact a position. This allows uhe correction gain control signal generated by che Lncer-ccr.trol-Loop correction section 17a tc be supcl-ied to the control input enc or the variable gam amplifier lib

via t^e D/A converter 16h. For the cantrol loop of system, b, Che veriabls gain a^-nplifisr lib is controlled by a correction gain control signal with variations in the circuit; characteristics such as the temperature characteristics and frequency characteristics of the circuit of systen b corrected by the inter-control-ioop correction section 17a/ based on the gain contrcl signal generated by the gain control, signal generator 15a of systeiti a selected as the highest level control loop. This allows the cptimun automatic gain control to be performed-
In step Sll/ in case the variation amount in the input
signals RIl, R12 is large and both of the variation amount Vad
and Vbd in the detected output are larger than or equal to the
preset threshold Kl (Vad and Vbd 5. Kll, operation switching
is made in the following way in step 516. The control section
turns ON the gain control signal generators 15a, 15b and turns
OFF the comparator 27 and the inter-control-loop correction
sections 17a, I7b as well as sets the control signal selector
switches 18a, iSb in the contact [3 position. This is for example
a case where the tecsiving field strength is siaall or variation
is large and the receiving state is unstable.^ In such a case,
the variation arr,oL:ncs Vad, Vbd in the detected output are large .
Autoraatic gain control is performed individually in aach control
loop ana the opti?nuri -: torr.atic gain control is executed in each
svstem. *•

As mentioned earlier, in che first emiDodime_it, in cass the variation amount in the detected, output"/ that is, in case Tihe input signal level is sff.all and the level is stable and automatic gain control characteristics are-nor impaired by the use of an approximate gain control signal, a control loop where the output signal level is the highest is selected and autcraatic gain control is performed using the gain control signal in the highesr-levei control loop. For the other control loops, a correction gain control signal containing correcz:ion of variations in circuit characteristics in each con-rol loop is generated based on the gam control signal to perform automatic gain control. This allows each control system to performproper automatic gain control via a gain control signal that supports variations in the circuit characteristics such as the temperature characteristics and frequency characteristics of the variable gain amplifier. In this case, operation of the gain control signal generators in the control loops other than the highest level control loop is turned OFF so than power consumption can be reduced if the control loop circuit is configured via hardware electronics. In case the control loop circuit is configured via the MPU (microprocessor unit) or DSP (digital signal processor) and operated via software programning, both the processing nime and the power cons"umption are reduced.
In case automatic cam control is oarformed with the

control loop where the input signal level is the highest is selected, no excessive signals are input to-the other control loops that are not selected. This avoids the disadvantage that the A/D converter ir. the subsequent stage of the variable gain amplifier is saturated.
On the other hand, in case variation amount in the detected output, that is, in ca.se the input signal level is large and the level is unstable thus high-accuracy automatic gain control IS required, a gain comirol signal is generated in each control loop and automatic gain control is performed individually. This executes the opti^num high-accuracy automatic gain control in each control system.
In the second to fifth einoodiiuents that follow, examples are shown where operation of the control section 19 according to the first errLbodiment is modified, since the configuration of the automatic gain controller is the same as that of the first enLOodiir.ent, the corresponding description is not given. I"Second embodir.ent]
Fig. 4 is a block diagram showing the internal configuration of a control section according to the second erabodinent. ^ig- 5 is a flowchart, showing the proaesiing procedure concerning autonvatic gain control according to the second eirijodiment.
The autom.atic gain controller according to rhe second enbodirient comprises, as the functional configuration o:S~the

control section 19, a variation a::acunt decision circuit 51 for determining wherherihe variation/imour.t Vad,-Vt)diri the detected output has reached a predeterznined value, a tij:ier circuit 52 for counting the elapsed tiir.e from when the automatic gain controller is powered, and a control circuit 50 for performing on/off switching of the gain control signal generator 15a, 15b, the inter-control-loop correction sections 17a, IVb and a coroparator 27," based on the output of the variation amount decision circuit 51 and the timer circuit 52 as well as the comparison result output of the comparator 27.
>7Gxt, operation of the automatic gain controller according to tr-e second embodiment will be described. In the second embodinent, inter-loop correction of the gain control signal is not laade but a gain, control signal is generated in each control loop to perform individual automatic gain control in the state w"nere the automatic gain controller is powered (initial state!, that is, in a certain period during systGm startup from -he non-operating state to the operating state, and control m the first embodiment is performed when the certain period has elapsed.
when the automatic gain centroiJ.er is powered and started, automatic gain control is started via a gain control signal so that the presec initial valua or conversion value is approached while counting of the predetermined time tl (sec.) is soar"ed via che timer circuit 52. The concroi secnc^n 19

determxries whether the predeterained time tl (sec.) has elapsed fro:ti when the power is turned on, based on the outpu- from the timer circuit 52 ir. step 521.
when the predetsrr.inad time tl (sec. ) has not yet elapsed frora when the power" Is turned on in step S21, the auoomatic gain controller places in the ON state (operating sta"e; the gain control signal generators 15a, 15b and places in the OFF state (non-operating state) the inter-control-loop correction sections 17a, i7b end the comparator 27 as well es sets the concrol signal selector switches ISa^ 18b in the contact p posinion, in step S22 . This allows each control loop to perform individual automatic gain control and proper automatic gain control is ei".ecuted in each control system.
When ths predetermined time tl (sec.) has elapsed froiTi when the power is turned on, the autom.atic gain controller perfor^is automatic gain control operation in the steady state, that is, automatic gain control operation in the first embodiment in step S23 . In this case, switching is made between the control vie the gain control signal in each control loop and the control via the gain control signal in the highest level control loop and jhe correction gala control signal in the non-highest leve L control loops, depending on the raagnitude of the variation amounts Vad, Vbd in the detected output.
The entire control section 19 may be configured via the M?U [microprocessor unit) or DSP (digital signal processor]

and Che timer circuit 52">^^s.y be realised vi.* a sofru-are timer or a hardware circuit. The timer circuit 52"is power-on reset at power-on and starts counting cime.
Inthisway, in the second efnbodiirient, in a certain psriod during system startup from the ncn-operating state to the operating stabe at power-on of the automatic gain controller, that is, in an unstable state where a Large variation amoun~ in che input signal level at zhe power-on operation is expected andhigh-accuracy automatic gain control is required, selective control is not made where operation of che control loops other than the control loop that obtains the ma/?imum detected output is turned OFr to perform inter-controi-loop correction but a gain control signal is generated in each control loop in a fixed way to perfoc!^ individual automatic gain CQr.trol. This executes the optimum high-accuracy automatic gain control in each control system. [Third eiRbodiment]
Fig, 6 is a block diagram showing the internal Configuration of a control section according to the third embodiment. Fig. 7 is a flowchart showing Che processing procedure concerning automatic gain control according to the third erabOGj-ment.
The automatic gain controller accozdinc! zc the third
embodiment comprises, as the functional configuration of the
I-
control section 15, a variation ancunt decision circuit 51 tor

determining whether the variation amoun-Vad, Vbdinche detected output in the steady operation has reached a predetermined value, an operation start variation an^.ount decision circuit 53 for determining whether th= variation amount Vad, Vbd in the detected output at power-on operation has reached a predetermined value, and a control circuit 50 for performing on/off switching ox the gain control slgnaJ. generator 15a, 15b, the inter-control-loop correction sections l7a, l"?b and a comparator 27, based an the output of the variation amount decision circuit 51 and the operation st=rt variation amount decision circuit 53 as well as the comparison result output of the comparator 27.
Next, operation of the automatic gain controller according to the third eiubodiment will be described. In the third embodiment;, inter-loop correction of the gain control signal is not made but a gain control signal is generated ::.n each control loop to perform individual automatic gain control ir. case variation amount in the detected output is large in the state where the automatic gain controller Is powered (initial state), that is, during system startup from the non-operating state to the operating state, and control in the first enitaodiaent is performed when the variation amount in the detected output has fallen within a predeter.T.ined level.
When the automatic gain contro Her is powered and started, automatic gain control is started via a gain con-rol Siignal

so thar the preset iniriai value or conversion value is approached and the operation start variation amoant decision circuit 53 determines whether the variation amounts Vad. Vbd have converged to a ,pr"Sds4;e"rmined level K2 (for example K2 > Kl) in step S31.
In case the variation amouncs Vad, vbd in the detected output are equal to or larger than the predetermined level K2 (Vad or Vbd ^ K2) in step S3l, the automatic gain controller places in the ON state (operating state) the-gain control signal generators 15a, 15b and places in the OFF state (non-operating state) the inter-control-loop correction sections 17a, l7b and the comparator 27 as well as sets the control signal selector switches 18a/ 18i> in the contact (3 pcsiTiion, in step S32. This allows each control loop tc perform individual automatic gain control and proper automatic gain control is executed in each control syste^L.
In case the variation amounts Vad, Vbd in the deuected output are smaller than the predetermined level K2 {Vad and Vbd
control loops, depending on cheir.agnitude of the variation amou:;^ Vsd, Vbd in zhe detected output.
Inthlsway, in the third9mbodimsn,t, during systsm startup
from the ron-opf^riting state to the operating state at power-on
or the automatic gain controller, that is, in an unstable state
where a large variation amoant in the input signal level is
expected and high-accuracy automatic gain control is required,
selective control is not made where the variation amount in
the detected output is determined and operation of the control
loops other than ths control loop that obtains the maxiKUir.
detected output is turned QzY to peirionr. inter-controi-lcop
correction when the variation amount is larga, but a gain control
signal is generated in each control loop in a fixed way ZQ perform
individual automatic gain control. This executes the optinvJirL
nigh-accuracy automatic gain control in each control system.
By setting a threshold value K2 used for decision in the
operation start variation amount decision circuiz 53 so that
imoynt de.cision circuit 51 in the steady state of the first
iEibodiiTLent (K2 > Kl) , it is possible to easily detect the
"ariation a^T-ount at power-or, when the variation amouni; is
renerally larger than that in the steady state. 3y combining
he operation according to ths third embodiment for determining
he variation amounts Vad, vbd in the detected output at power-on
nd the operation according to the secondeirijodiir.ent for scaVting

to count a predetermined time tl at power-on, a more minute automatic gain control at power-on. can be" performed-[ Fourth emfoodir.ent 1
Fig. S is-"a ■■f-iowdi^.art-showing tiie processing procedure concerning automatic gain control according to Lhe fourth embodimenr. The fourth embodiment is an example of the case where the automatic gain controller performs intermitrent operation . This embodiment is preferable for a case where radio communications apparatus performs intermittent reception. Since the functional configuration of the control section 19 is alrr.ost the same as Chat of the second embodiment shown in Fig. 4, the corresponding description is not given.
In the fourth em}?odiment, Intsr-loop correction of the gain control signal is not made but a gain control signal is generated in each control loop to perform individual automatic gain control ar the start of each, intermittent operation, that is, in a certain period during system, starrup from the non-operating state to the operating state for intermittent operation, and control in the first embodiment is perforned when the ceri:ain period has elapsed.
When "he automatic gain controller starts intermittenc operation, automatic gain control is started via a gain concrol signal so rhat the preset initial value or conversion value is approached while counting of the predetermined rime t2 (sec . ) ifor e-xamole t2
control section 19 determines whether the predetermined tirne t2 (^p-c.) has elapsed fron when ths intermittent operatic^- "-^as started, based or, the output from the timer circuit 52 in step 341.
Knen thd predetermined time t2 (sec.) has riot yet elapsed from when intermittent operation was started in step 41, the automatic gain controller places in the ON state (operating state) the gain control signal generators 15a, 15b and places in the OFF state (non-operating state) the inter-concrol-loop correction sections 17a, I7b and the comparator 27 as well as sets the control signal selector switches 18a, 13b in the contact (3position, instep 34 2 . This allows each control loop ^Qperform individual automatic gain control and proper automatic gain control is executed in each control system.
When the predetermined time t2 (sec.) has elapsed from when the internitten:: operation was started, the automatic gain controller performs autom.atic gain control operation in the steady state, that is, automatic gain control operation in the first embodiment in step S4. In uhis case, switching is nade between the control via the gain control signal in each control loop and the control via the gain control signal in the highest level control loop and the correcrion gain control signal in the non-highesc level control loops, depending on the magnitude of the variation amounts Vad, Vbd in the detected output.
The time when the system, is unstable is generally shcrter

in t!ie internittent operation tnan at power-on. By setting the timer se- value t2 for intermittent operation so tha-t t2-. is smaller than the ti~er set value tl of the tinier s-arred at power-on, it is possible to quickly shift to automatic gair-control in the steady state.
In this way, in the fourth embodixenc, in a certain period during systen startup from the non-operating state to the operating stata for intarmitcent operation by the automatic gain controller, that is, in an unstable state where a large variation amount in the input signal level for incer-Tiittent operation is expected and high-accuracy automatic gain control is required, selective control is not made where operation of the control loops other than the control loop that obtains the maximum detected output is turnad OfF to perforra inter-control-loop correction but a gain control signal is generated in each control loop in a fixed way to perform individual automatic gain controi . This executes the optimu.^ high-sccuracy automatic gain control m each control system. [Fifth embodiment]
Fig. 9 is a flowchart showing the processing procedure concerning automatic gam controi according to the fif^.^ , embodiment. The fifth embodiment is an example of the case "where the automatic gain ccnuroller performs intermitteni; operation. This embodiment; is preferable for a case where radio comnunicaticns apparatus performs intarmittent reception.

Since the functional configuration of the control section 19 is almost the same as that of the third esabodinent shown in Fig. 5, the corresponding description is not given.
In the fifth erritaodiment, inter-loop correction o^ the gsin control signal is not ir.ade but a gsin control signal is generated in e^ch control loop to perform individual automatic gain control at the start of each intermittent operation, that is, during system startup from the non-operating state to rhe operating si;ate for antermitten^ operation, and control in the first en±iodiir_ent is performed when the variation smounc in the detected output has fallen within a predetermined level.
When the automatic gain controller starts intermittent operation, a^Jton-Latic gain control is started via a gain control signal so that the preset initial value or conversion value is approached and the operation start variation amount decision circuit 53 determines whether the variation amounts Vad, Vod have converged to a predetermined level K3 (for exanple K3 > Kl) in step S51.
In case the variation amounts Vad, Vt>d in the detected output are equal to or larger than the predetermined level K3 (Vad or Vbd ^ K3) in step 351, the automatic gain controller places in the OX state (operating state) the gain control signal generators 15a, 15b and places in the OFF state (non-operating state) the inter-control-loop correction sections 17a, 17b and the comparator 27 as well as sets the control signal selkector

switches 18a, leb in the contact (3 position, in step S52. This ailcws sach control loop to perform individual autcm-atic gain control and proper automatic gain control is executed in each control sys"ett..
- In cas^e the variation aniounts Vad, Vbd in the detected output ere smaller than the prsdetermined level K3 (Vsd and Vbd Inthisway, in the fifth erobodiraent, duringsysterr-startup fro.Ti the non-operating state to the operating state for interrr.ittent operation by the automatic gain controller, that is, in an unstable state where a large variation amount in the input signal level is expected and high-accuracy eutomstic gain control is recuired, selective control is not made where the variation amount in the detected output is determined and operation of the control loops other than the control loop that obtains the m3>;imun". detected output i^ turned OFF to perform inter-con-rol-loop correction when the variation amouRt is

large, but a gain, control signal is generated in each control loop in a fixed way to perform, individual automatic gain control. This executes the optimuzr. high-accuracy automatic gain control in each control system.
By setting a threshold value K2 used for decision in the operation start variation ain.ount decision circuit 53 so that K3 is larger than the threshold value Kl used in the variation amount decision circuit 51 in the steady state of the first e-Tibodiment and : Fig- IC is a block diagram showing the configuration or :=dio corrjr.ur.ications apparatus according to an embodiment of ",he invention. Tha sixth embodiraent shovv^s an examnlfe" of

configuration of radio corjnunications apparatus equipped wich an automatic gain controllar according to the aforen;entioni=d :first through fifth emijodiments.
the radio cormnunications apparatus is composed of receivers of aplurality of systems (two systems in this ex^i^plel . The radio communications apparatus comprises antennas 71s, lib, an antenna multiplexer 72, bar.d-pass filter (BPTj used in the RF band (radio frequency band) 73a, 73b, low-noise aziplifiars 74a, 74b, down-mixers for frequency-converting signals in the KT band to signals in the IF [interrriediate frequency) band, band-pass filters (EPr"s) 763, 76b used in the IF band, an autorr.atic gain control circuit (AGC) 77, a frequency synthesizer 78, a receiver (RFC) 79 for outputting received signals in the form of voice data, a transceiver controller 80 for perfarming control of each section, a transmitter circuit 31 for processing send signals, a key input section [KEY) 82 for performing a variety of operations, amicrophone (MIC) 83 for inputting \"oice data as a send signal, and a battery (BATT) 84 for supplying power to each section. The automatic gain control circuit 77 formed control loops at the receivers of the systems used, as shown in the first embodiment in Fig. 1.
Operation of the radio communications apparatus will be described. When radio signals (assume for example signals in the 2-GHz band) are received via antennas 7ia, 7ib, the receivec
signals cass throuah the antenna multiplexer 72 and signal
I-

coraponents in a predetermined band are attenuated by the band-pass filters "3a, 73b and signal compgnents in a desired frequency band are respectively pass through the filters and output. The received signals that passed throi:gh the band-pass filters V3a, 73b are respectively arr.pli^ied by the low~noise amplifiers 74a, 74b and frequency-converted by to signals in the IF band (for example 330 [MHz] band) by the down.-tTiiy.ers 75a, 75b, then input to the automatic gain control circuit 77 via the band-pass filters "^69, 76b, iri one system
The received signals are demodulated by a demodulator provided in the automatic gain, con-crol circuit 77 aad output to the transceiver controller 80 as baseband signals anduridergo signal processing, "n this practice, processing explained in the aforem.entioned first through fifth embodinients is performed in the control loops of the systems in the aiitoiri.atic gain concrol circuit 77 . A generated gain control signal or correction gain control signal is supplied to a variable gain amplifisr for preferable automatic gain control.
In case the receiving field strength is stable and variation in the received signal level is small thus receiving characteristics are not impaired by the use of an approximate gain control signal, a control loop where the output signal level is The highest is selected and auromatic gain control is performed using the gain control signal ir. the highest-level control loop. For the other control loops, a correctiomgain

control signal containing correction of variations in circuit characteristics in each central loop is generated based on the gain control signal to perform automatic gain control. This allows each control system to perform proper automatic gain control via a gain control signal that supports variations in the circuit characteristics such as the temperature characteristics and frequency characteristics of the variable gain ampllfiej:. In this case, operation of th.§ gain control signal generators in the control loops other than rhe highest level control loop is turned OFF so that power cons"omption can be reduced. In this case, control is always raade by selecting a control loop where the received signal level is the highest, no excessive signals are input to the other control loops that are not selected, This avoids the disadvantage that the A/E converter in the subsequent stage of the variable gain ajnplif ier is saturated.
On the other hand, in case the receiving field strength
is unstable and the variation in the received signal level is
large and high-accuracy automatic gain control is required,
;uch as when the receiving environment has changed and signal
iropagacion is deteriorated with fading taking place,
ndividual automatic gain control is perforn:ied via a gain control
ignal in each control loop. This executes the optiir.um
igh-accuracy autorriatic gam control in each control systera
nd provides operation foCvising on the receiving performance.

thereby obtaining a preferatola received signal.
In case a large variation in the received signal level is expected andhigh-accuracy automatic gain control is required during system startup at power-^on^ Individual automatic gain control is performed via a gain control signal in each control Loop, without selecting the highest level control loop or correcting a gain control signal in a certain period from power-on as in the second eirLbodimerit, or until the variation amount in the detected output converges within a predetermined value as in che third enibcdiKient. This executes the octiraum high-accuracy automatic gain ccn-croi in each control system and provides operation focusing on the receiving performance, thereby obtaining a preferable received signal.
In case a variation ir. the received signal level is large and high-accuracy automatic gain control is required during system startup when each intermittent operation is started, ir\di vidua! automatic gain control is per formed via a gain control signal in each control loop, without selecting the highest level control loop or correcting a gain control signal in a certain period from power-on as in the fourth embodiment, or until the varia-ion amount in the detected output converges within a prederermined value as in the fifth embodiment. This also executes the optimum hii^h^accuracy automatic gain control In each control system and.provides operation focusing on the receiving performance, thereby obtaining a preferable received

signal
As mentioned earlier, accordir.g to tne invention, it is possiiDle tc execute automatic gain control of a plurality of systems depending on the operating state such/as stable/unstable signal level and to obtain proper automatic gain control performance in each system as well as to reduce power consumption.

WHAT IS CLAIMED IS:
1. An automatic gain controller having variable gain amplifiers of a plursality of systems and ths corresponding control loops, comprising:
a gain control signal generator which generates a gain control signal that controls a variable gain amplifier based on the output signal level of the variable gain amplifier;
a variation amount detector which detects the variation amount of the output signal level;
am level comparator which compates the output signal levels
of the plurality of system with each other; ^
a inter-control-loop correction section which generates a. correction gain control signal that corrects variations in the circuit characteristics of the other control loops and that is based on a gain control signal in the control loop where the output signal level is the highest in order to perform gain control; and
a operation ,controller which selects the control Icop where ths output signal level is the highest, places the gain/ gontrol signal generator for the other control loops in the non-operating state, and performs gain control of the variable gain amplifiers of the plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other

control loops, xn case the variation amount in the output signal
level is smaller than a predetermined value.
2. Ar. automatic gain controller according to claim 1, wherein the operation ccntroller places in the operating
state the gain concrol signal generator for the control loops of the pluralicy of systems and performs gain control of the ,"
r
variable gain am.plif ier via a gain control signal in each control loop, in case the variation amount in the output signal level is larger than the predetermined value.
3. An automatic gain controller according to claim 7, wherein the operation controller operates the gain control
signal generator for each control loop in a preaetermined period during system startup from the non-operational state at power-on,
to perform gem control of the variable gain amplifier.
4. An automatic gain controller according to claim. 1, wherein the operation controller operates the gain control signal generator for each control loop until the variation amount in the output signal level falls within a predetermined vaiue during system startup from the non-operational state ac power-on, to perform, gain control of the variable gain amplifier.
Ar_ autor.atic gain controller according to cLaim

1, wherein the Ciperatior. controller operates the gain control signal generator for each control loop in a predeterminedperiod during systsra startup frorTi the non-operational state in case intermittent operation Js performed, to perforin gain control"
r
ot the variable gain amplifier. V
5. An automatic gain controller according to claim
"L, whersin the operatian controller operates the gain control
signal generator for each control loop until the variation amount in the catput signal level falls within a predetermined value during sysrex startup frciTi the non-operational state in case intermittent operaticn is performed, to perform gain control/ of Che variable gam amplifier.
7, An automatic gaia control raethod using variable gain amplifiers of a plurality of systems and the corresponding control loops,,, coniprising:
a gain control signal generating step for generating a gain control signal that control a variable gain amplifier based on the output signal level of the variable gain aniplifier;
a variation amount detecting step for. detecting the variation amount of the output signal;
a level comparison step for comparing the output signali

levels cr the plurality of system with each other;
an inter-control-locp correction step for generating a

correction gain control signal that corrects variations in the circuit cheracterisrics of the other control loops and thac is basse on a gain control signal in the control loop where the output signal level is the highest in order to perform gain control; and
an operation control step for selecting the control loop

where the output signal level is the highest, placing a gain control signal generator for the other control loops in the non-opera ting state, and per forming gein control of the variatble gain amplifiers of the plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in case the variation amount in the output signal Level is smaller than a predetermined value.
6 . An automatic gain control method according to claim 7, wherein the operation control step places in the operating State Che gain control signal generator for the control loops of the plurality of systems and performs gain control of the variable gain amplifier via a gain control signal in each control oop, in case the variation amount in the output signal level 5 larger than the predacermined value.
9 . An automatic gain control method according to claim , wherein the operation control step operates the gam control

signal generator for each control loop in a predetermined period during system startup from the non-operational state at power-on to perform gain control of the variable gain anplifier.
10. An autonatic gain control method according to claim. 7, wherein the operation control step operates the gain control signal generator for each control loop until the variation amount in the output signal level falls within a predetermined value during system 3-artup from the non-operational statear power-on, to perform gain control of the variable gain amplifier.
1l. An automatic gain control method according to claim 7, wherein ths operation control step operates the gain control signal generator for each control loop in a predetermined period during systsn startup from the non-operational state in case intermittent operation is performed, to perform gain control of the variable gain amplifier.
12 . An automatic gain control method according to claim
7, wherein the operation control step operates the gain control
signal generator for each control loop until the variation amount
in the output signal level fails within a predeter."nined value
during systerr. startup from the non-operational state in case
intermittent operation is performed, to perform gain control
of the variable gain amplifier.

13. A Radio cominunications apparatus having receivers
of a plurality of systems comprising an automatic gain controller which includes:
a gain control, signal generator which generares a gain control signal that controls a variaole gain err.plifier based on the output signal level of the variable gain amplifier;
a variation aimount deteccor which detects the variation amount of the output signal level;
a level comparator which compares the output signal levels of the pluraliity of system with each other;
a inter-control-loop correction section which generates a correction gain control signal that corrects variations in the circuit characteristics of the other control loops and that is based on a gain control signal in the control loop where the output signal level is the highest in order to perform gain control; and
a operation controller which selects the control loop where the output signal level is the highest, places the gain control signal generator for the other control loops in the non-operatir.g state, end performs gain control of the variable gain amplitiers of the plurality of systems via the gain control signal in the control loop where the output signal level is the highest and correction gain control signals in the other control loops, in case the variation ancunt in the output signal

level is smaller than a predetermined value.
14. . A automatic gain controller substantially as herein described with reference to the accompanying drawings.
(0} A radio communications apparatus substaotially as herein described with i reference to the accompanying drawings.

Documents:

189-mas-2001 abstract duplicate.pdf

189-mas-2001 abstract.pdf

189-mas-2001 claims duplicate.pdf

189-mas-2001 claims.pdf

189-mas-2001 correspondence others.pdf

189-mas-2001 correspondence po.pdf

189-mas-2001 description (complete) duplicate.pdf

189-mas-2001 description (complete).pdf

189-mas-2001 drawings duplicate.pdf

189-mas-2001 drawings.pdf

189-mas-2001 form-1.pdf

189-mas-2001 form-19.pdf

189-mas-2001 form-26.pdf

189-mas-2001 form-3.pdf

189-mas-2001 form-5.pdf

189-mas-2001 others.pdf

189-mas-2001 petition.pdf

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Patent Number

201835

Indian Patent Application Number

189/MAS/2001

PG Journal Number

08/2007

Publication Date

23-Feb-2007

Grant Date

14-Aug-2006

Date of Filing

02-Mar-2001

Name of Patentee

MATSUSHITA ELECRIC INDUSTRIAL CO., LTD

Applicant Address

1006, KODOMA KADOMA-SHI OSAKA.

Inventors:

#	Inventor's Name	Inventor's Address
1	NOZOMI MIURA,	3-1-1-303, OOKA MINAMI-KU YOKOHAMA-SHI KANAGAWA 232-0061.

PCT International Classification Number

H03G3/20

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2000-59025	2000-03-03	Japan