A two-stage bipolar amplifier is shown in Fig. 7.47. Calculate the low-frequency, small-signal voltage gain Ï…_o/Ï…_iand use the zero-value time constant method to estimate theˆ’3-dB frequency. Use a DM half-circuit for the differential pair. Use SPICE to estimate the first and second most dominant poles of the circuit. Data: npn: β = 200, f_T= 400 MHz (at I_C= 1 mA), C_μ= 0.3 pF, C_je= 3 pF, C_cs= 1.5 pF, r_b= 0, V_BE(on)= 0.6 V, and r_o= ˆž. pnp: β = 100, f_T= 6 MHz (at I_C= ˆ’0.5mA), C_μ= 0.3 pF, C_je= 3 pF, C_bs= 1.5 pF, r_b= 0, V_BE(on)= ˆ’0.6 V, and r_o= ˆž. (All values of C_μ, C_cs, C_bs, and C_jeare at the bias point.)

Fig. 7.47:

Transcribed Image Text:

+6 V 1 k2 12.5 k2 12.5 k2 Оз 10 k2 Q2 Q1 10 k2 10 kQ Q4 10 k2 Q5 2.5 k2 1 k2 -6 V