28 如圖所示之電晶體放大器電路中增強型 MOSFET 的相關參數為 μnCox(W/L) =2 mA/V2 和臨界電壓 Vth =1 V,測得輸出直流偏壓電壓 Vo = VDSQ = 6 V,該偏壓下電晶體的小信號互導 gm 約為多少? (A)0.4 mA/V (B)2 mA/V (C) 4 mA/V (D) 10 mA/V
gm = 2k (Vgs - Vt) = 2 ( Id * k )^(1/2)
2k = unCox (W/L)
Id = (12 - Vo) / Rd = (12 - 6) / 1.5k = 4mA
gm = 2 * ( 4m * unCox (W/L) / 2 ) ^ (1/2)
= 2 * ( 4m * 1m ) ^ (1/2) = 2 * 2m = 4mA/V
28 如圖所示之電晶體放大器電路中增強型 MOSFET 的相關參數為 μnCox..-阿摩線上測驗