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usRsRbReRLECC1C2+ui-UBE+uo-2.2.2共集电极电路(射随器)1电路结构(1)发射极接负载,又称射极输出器(2)输入信号与输出信号同相,大小基本相等,又称射极跟随器(3)输入阻抗大,输出阻抗小,具有隔离阻抗变换的作用(4)在IC电路中常用有源负载射极跟随器返回电路仿真休息1休息2RbReECUBEusRsRbReRLECC1C2+ui-UBE+uo-2.射随器微变等效分析:(1)交流通道:(2)直流通道IBUBIEUB=EC-IBRb=UBE+(1+hfe)IBReIB=(EC-UBE)/(Rb+(1+hfe)Re)IC=hfeIBUCE=EC-IERe+UCE-usRsRbReRLECC1C2+ui-UBE+uo-休息1休息2usRsRbReRL返回hfeibhierceusRsReRLRbhiehfeibrcehiehfeibrceusRsRbReRL2.射随器微变等效分析:(3)微变等效电路:休息1休息2返回hfeibhierceusRsReRLRb2.射随器微变等效分析:(4)交流参数:'')()////)(()////()(.LfeieceeLfeiebceeLbfebiebiiRh1hrRRh1hirRRih1ihivR其中:RL’=RL//Re(或ro2)//rceⅰ输入电阻:Ri=Rb//Ri’RiR’iib(1+hfe)ib+ui-休息1休息2返回hfeibhierceusRsReRLRb2.射随器微变等效分析:ii:输出电阻:输入端短路(或信号源短路)Ro=Re//Ro’;Rs’=Rs//Rbbfesieoceooo0'oih'Rhuruu'iuRfesiecehesieoceooh1'Rh//r)h1('RhuruuR’o'sieobRhviRo+uo-ioio'ibRs'休息1休息2ceoruhfeib返回hfeibhierceusRsReRLRb2.射随器微变等效分析:iii:电压增益:1Rh1hRh1Rh1hiRh1ivvALfeieLfeLfeiebLfebiov'''')()()()(一般1Avieib休息1休息2+uo-+ui-返回Rb1Rb2ReRcECusRsRb1ReRLRb2RcECC1C2Ce2.2.3共基极(CB)放大电路1电路结构:C1,C2:为输入和输出耦合电容Cb:基极旁路电容电路特点:发射极输入,集电极输出(2)工作点估算ceCCCCEeBEBCCEcc2b1b2bBIRRVVRVVIIIVRRRV2静态工作点(1)直流通道:UBIE+UCE—+UBE—电路仿真休息1休息2返回hiehfeibrceRcRLReRsushiehfeibrceRsusReRcRLusRsRb1ReRLRb2RcECC1C2Ce3交流参数分析(1)交流通道:(2)微变等效电路:休息1休息2返回hiehfeibrceRcRLReRsus3交流参数分析:(3)输入阻抗:'//ieiRRR如果忽略rce,则:1hihii.hiu'Riebfebbieeii(EB间输入阻抗小)RiRi’ieib+ui-休息1休息2返回RsRehiercehfeibhiehfeibrceRcRLReRsus3交流参数分析:(4)输出阻抗:'//oc0RRR注意在计算R0’时要考虑rce,否则R0’=∞RoR’oR’oiibie'sceie's'sfeie'sceieSSfe0ieSSieieSbie'scebfe000h//Rr)hRRh1(i)h//R(iirhRRh1RihRRh)h//Rii)h//R(irihiuiuR而R's休息1休息2+uo-返回hiehfeibrceRcRLReRsus3交流参数分析:ieib(5)电压增益:ie'Lfei0uhRhuuA)R//RR(Lc'LCB电路、电压增益大,输出电压与输入电压同相位。(6)电流增益:1RRRRRRiiiiiiiiALCCieec0eciei0i'icioii休息1休息2+uo-+ui-返回§2.3BJT组合放大电路2.3.1CE-CB串接放大电路2.3.2CE-CC组合放大器返回R1RcR3ReRsusRLECCBC1C2CeR2R1R2R3RcReEC2.3.1CE-CB串接放大电路(1)直流通道UB1UB2C32131BERRRRUC321322BERRRRRUIC2Ie2=IC1Ie11e1C2e2CIIIIe1BE1B1eRUUI)UU()UU(U1BE1B2BE2B1CE)RR(IUEUeC1e1CEC2CE电路仿真UBE1UBE2返回RsusRbRcRLR1RcR3ReRsusRLECCBC1C2CeR22.3.1CE-CB串接放大电路(2)CE-CB放大电路的交流通道电路特点:具有两种组态的优点CE:Ai,Ri较大CB:Av,Ro较大比单级CE具有较高的增益(主要用于高频放大的电路)休息2休息1Rb=Rb2//Rb3返回RsusRbRcRL2.3.1CE-CB串接放大电路(3)电路参数:i输入电阻:'//ibiRRR而1ieihRRiR’iii输出电阻:2ce2fe2ie1ce2ce2ie1ce1ce2fe2ies2ce2iess2fe0oC0rh1hrrhrrh1hRrhRRh1RRRR)(//)(//)(//''''R’oRo返回RsusRbRcRL(3)电路参数:iii电压增益iecfe2iec2fe1ie2fe2ie1fe2u1u010i01i0uhRhhRhhh1hhAAuuuuuuA(如果fefefehhh21ieieiehhh21)Ri2Ri2=2fe2ieh1h2.3.1CE-CB串接放大电路+uo-+uo1-+ui-返回RLRc1Rb12Re1RsusRb11ECC3C1CeRb2C2Re22.3.2CE-CC组合放大器2.CE-CC组合放大器(1)直流通道(2)交流通道继续RLRc1Rb12Re1RsusRb11ECC3C1CeRb2C2Re2电路仿真Rb11Rb12Re1Rc1ECRb2Re2ECRb1Rb2RsusRc1Re2RL返回
本文标题:94射随器
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