高二物理竞赛课件共漏级放大电路

共漏级放大电路又称源极输出器或源极跟随器RG+VDDSDG+-uiuo+-共漏级放大电路R1R2RSC1C2RL静态分析可用近似估算法或图解法求解过程可参阅分压偏置式共源放大电路共漏级放大电路上一页返回下一页uDSOiDuGS

=4.5V4V3.5V3V2VVDDRS+RDUDSQVDDIDQuDS

=

VDD-

iD

(

RD+

RS)RGRD+VDDSDGR1R2RSVGIDID+-UDS+-UGS上一页返回下一页3.动态分析RDUo+-idUi+-RGR2R1RLUo=-gmUgsR΄DUi

=

UgsR΄D=

RD//

RLRGRD+VDDSDG+-uiuo+-R1R2RSC1CSC2RL仿真gmUgsUgs+-SDG上一页返回下一页uoRc2T2+VCCRb1T1+ui-+-VDZRc1ic1

ib1+-

ui+-

uoic2

ib2Rc2Rc1Rb1rz解：rbe1β1ibcberbe2β2ibcbe下一页返回上一页ic1

ib1+-

ui+-

uorbe1β1ibcbeic2

ib2Rc2Rc1Rb1rbe2β2ibcberz+-

uo1ui2Ri2Ri2=rbe2+（1+β2

）rz应将第二级的输入电阻看作第一级的负载电阻Au1=uo1

uiuo1=-β1ib1（Rc1//Ri2

）ui=ib1rbe1=-β1（Rc1//Ri2

）rbe1下一页返回上一页uo=-β2ib2Rc2ui2=ib2[rbe2+（1+β2）rz]Au2=uo

ui2=-β2Rc2rbe2+（1+β2）rzAu2=Au1

·Au2Ri=Rb1//

rbe1Ro=Rc2

ic1

ib1+-

ui+-

uorbe1β1ibcbeic2

ib2Rc2Rc1Rb1rbe2β2ibcberz+-

uo1ui2下一页返回上一页[例]已知VCC

=

VEE

=18V，静态时uo

=0，估算静态工作点、电压放大倍数、输入电阻和输出电阻~Rc2T2+VCCRsRc1T1+ui-+uo-Re2-VEE+us-Re15.6kΩ200Ω4.7kΩ1.2kΩβ1=50β2=30下一页返回上一页下一页返回上一页Ic2=VEERc2=184.7=3.8mAIB2=ic2β2=0.13mAIE2=Ic2+IB2=mAI1

Rc1=IE2Re2+UBE2I1=IE2Re2+UBE2Rc1=0.98mAIc1=IB2+I1=mAIB1=ic1β1=0.022mAIE1=IB1+Ic1=mAUE2=Vcc–IE2Re2=VUC1=UE2–|UBE2|=V~Rc2T2+VCCRsRc1T1+ui-+uo-Re2-VEE+us-Re15.6kΩ200Ω4.7kΩ1.2kΩiB2I1ic1ic2iE2下一页返回上一页电路等效模型ic2

ib2Rc2+-

ui+-

uoio

iiRc1~Rsus~Rc2T2+VCCRsRc1T1+ui-+uo-Re2-VEE+us-Re1ic1

ib1Re2Re1rbe1β1ib1cebrbe2β2ib2ceb下一页返回上一页+-ic2ib2Rc2+-

ui

uoio

iiRc1~Rsusic1ib1Re2rbe1β1ib1cebrbe2β2ib2cebRe1Ri2Ri2=rbe2+（1+β2

）Re2uo1=-β1ib1（Rc1//Ri2

）ui=ib1[rbe1+（1+β1

）Re1]Au1=uo1

ui=-β1（Rc1//Ri2

）rbe1+（1+β1

）Re1下一页返回上一页+-ic2ib2Rc2+-

ui

uoio

iiRc1~Rsusic1ib1Re2rbe1β1ib1cebrbe2β2ib2cebRe1uo=-β2ib2Rc2Ri=rbe1+（1+β1

）Re1ui2=