A two-stage amplifier is shown in Fig. 7.46. Calculate the low-frequency, small-signal gain and use the zero-value time-constant method to estimate the ˆ’3-dB frequency. Calculate the 10 to 90 percent rise time for a small step input. Use SPICE to determine the ˆ’3-dB frequency and also the frequency where the phase shift in the transfer function is ˆ’135—¦ beyond the low-frequency value. Data: β = 200, f_T= 600 MHz at I_C= 1 mA, C_μ= 0.2 pF, C_je= 2 pF, C_cs= 1 pF, r_b= 0, V_BE(on)= 0.6V, and r_o= ˆž. (Values of C_μ, C_cs, and C_jeare at the bias point.)

Fig. 7.46:

Transcribed Image Text:

+6 V 5 k2 10 k2 10 k2 Vo 20 k2 Q1 02 03 Q4 :20 k2 3 5 k2 5 k2 O5 2 k2 1 k2 -6 V