**10.107 Consider the BiCMOS amplifier shown in Fig. P10.107. The BJT has | VBE| = 0.7 V, B = 200, C=0.8 pF, and fr = 600 MHz. The NMOS transistor has V₁ = 1 V, k, W/L = 2 mA/V², and Cgs = Cgd = 1 pF. (a) Consider the dc bias circuit. Neglect the base current of Q₂ in determining the current in Q₁. Find the dc bias currents in Q, and Q₂, and show that they are approximately 100 μA and 1 mA, respectively. (b) Evaluate the small-signal parameters of Q, and Q, at their bias points. (c) Consider the circuit at midband frequencies. First, determine the small-signal voltage gain V/V. (Note that RG can be neglected in this process.) Then use Miller's theorem on R to determine the amplifier input resistance R. Finally, determine the overall voltage gain V/V Assume r, of both transistors to be very large. (d) Consider the circuit at low frequencies. Determine the frequency of the poles due to C, and C₁, and hence estimate the lower 3-dB frequency, fr. sig" (e) Consider the circuit at higher frequencies. Use Miller's theorem to replace RG with a resistance at the input. (The one at the output will be too large to matter.) Use open-circuit time constants to estimate fμ- V sig + 100 ΚΩ www ΜΩ RG = 10 MQ +5 V 3 ΚΩ C2 V 0 C₁ 1 μF Q₁ 1 ΚΩ 0.1 μF Q2 6.8 ΚΩ Rin Figure P10.107