An amplifier stage is shown in Fig. 7.44.

(a) Calculate the low-frequency, small-signal voltage gain Ï…_o/Ï…_i.

(b) Apply the zero-value time-constant method to the DM half-circuit to calculate the ˆ’3-dB frequency of the gain. Data: C_cs0 = 2 pF, C_μ0 = 0.5 pF, C_je = 4 pF (at the bias point), f_T = 500 MHz (at I_C = 2 mA), β = 200, r_b = 0, and r_o = ˆž. Assume n = 0.5 and ψ₀ = 0.55 V for all junctions.

Fig. 7.44:

Transcribed Image Text:

+6 V 5 k2 5 k2 10 k2 10 k2 Q4 Q3 Q2 10 μΑ 10 μΑ 1 mA -6 V W-