32. 如圖(十六)所示之電路,電晶體 β = 100,切入電壓 VBE = 0.7V 且熱電壓 VT = 25mV,則 a 小信號電流增益 IE /IS為何?
 
(A) 1.0
(B) 40.3
(C) 50.7
(D) 65.2 

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統計: A(4), B(2), C(5), D(27), E(0) #676685

詳解 (共 2 筆)

#3705452
先求出IB電流=15-07/370k+2...
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#3763263

電流增益 (Ai) = Io / Ii  =>   IE / Is


IB = (15 - 0.7) / [370k + (100+1)*2k ] = 0.025

π = VT / IB = 25m / 0.025 = 1k

 

IE (Io) = 1k ib + 100k ib = 101k ib

Is (Ii) = [ ib + ib*1k + (100+1)*ib*2k ] / 370k = (573k / 370k)ib

Ai = Io / Ii => IE / Is = 101k ib /  (573k / 370k)ib = 65.2........

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