AMOS cascode stage is shown in Fig. 7.43b. Replace the load resistor with a load capacitor C_L= 2 pF. Assume the total capacitance that connects to the drain of M1 can be modeled by a capacitor C_p= 0.2pF from that drain to ac ground. Ignore all other capacitors. Therefore, the gain for this circuit has only two poles. For both transistors, take I_D= 100 µA, W = 20 µm, L_eff= 0.5 µm, k’ = 180 µA/V², and λ = 0.04 V^−1.

(a) Use zero-value time constants to estimate the dominant pole.

(b) Use short-circuit time constants to estimate the nondominant pole.

Figure 7.43 (b):

M2 Rs M1 R1 Vo