【評論主題】20 圖中電晶體的 VT = 25 mV，β = 100，VBE = 0.7 V，其電流增益（io / ii）約為： (A)8.3(B)10.1(C)83(D)101

【評論內容】

共集極 CC  Av=1

Ri = 100K//(1+B)(10K//10K) = 83.33K

Ro = 10K

Ai = Av* Ri/Ro = 1*83.33/10 = 8.33