4.(30%) Consider the BiCMOS amplifier shown in Fig. 4 has= 100 kΩ, R_G = 10 MΩ, Rs = 6.8 kΩ, R_c = 3kΩ, R_L= 1 kΩ, C_I= 0.1 μF, C₂ = 1 μF. The BJT has 0.7 V, β = 200, Cμ = 0.8 pF, f_T = 600 MHz, and thermal voltage V_T= 25 mV. The MOSFET has = 1 V, = 2 mA/V², and= 1 pF. Neglect the Early effect and channel length modulation effect. (a) Consider the DC bias circuit. Neglect the base current of Q2 in determining the current in Q1. Find the DC drain current in Q1 and collector current in Q2. (b) Consider the circuit at low frequencies. Deternine the frequency of the poles due to C1 and C2. (c) Consider the circuit at higher frequencies. Use open-circuit time constants to estimate f_H. (5%,5%,5%,5%,10%)

3.(30%) The amplifier shown in Fig. 3 has =R_L = 1 kΩ, R_c= 1 kΩ, R_B = 47 kΩ. The BJT has 0.7 V, β= 100, Cμ = 0.8 pF, f_T = 600 MHz, and thermal voltage V_T = 25 mV. Assume the coupling capacitors to be very large. Neglect the Early effect. (a) Find the collector current of the transistor. (b) Find the overall gain vdvsig and the input resistance at midband frequency. (c) Find the high frequency response f_H. (5%,5%,10%,10%)

2.(20%) Figure 2 shows a BJT circuit with the = 200 kΩ, RE = 5kΩ, Rc =2 kΩ, R_L= 5 kΩ. The BJT has0.7 V, β = 100, thermal voltage V_T = 25 mV. Neglect the Early effect. (a) Please find the DC collector current I_c. (b) For AC analysis, please find the input resistance Rin, output resistance Rout and overall gain . (5%*4)