40. 如下圖所示電路,電晶體工作於作用區,β = 99,VBE = 0.7 V,熱電壓(thermal voltage) VT = 26 mV,I則此放大電路之電流增益
【用戶】Neng Kuan Lin
【年級】小一上
【評論內容】輸入端作戴維寧簡化,求直流Ib,電容開路Vb=9.8v,Rb=100K,Ib=(9.8-0.7)/[Rb+(1+β)RE]=9.1/100k+600k=0.013mArπ=VT/Ib=26/0.013=2KΩ代入小訊號模型求ZiZi=100k//[2k+(1+β)(RE//RL)]=100k//300k.....2k忽略Zi=75kAi=±|AV|*Zi/Rio............... Rio為Io流經的電阻,共集極AV≦1Ai=75k/6k=12.5選D
【用戶】Neng Kuan Lin
【年級】小一上
【評論內容】輸入端作戴維寧簡化,求直流Ib,電容開路Vb=9.8v,Rb=100K,Ib=(9.8-0.7)/[Rb+(1+β)RE]=9.1/100k+600k=0.013mArπ=VT/Ib=26/0.013=2KΩ代入小訊號模型求ZiZi=100k//[2k+(1+β)(RE//RL)]=100k//300k.....2k忽略Zi=75kAi=±|AV|*Zi/Rio............... 共集極AV≦1,Rio為Io流經的電阻Ai=75k/6k=12.5選D