Use the short-circuit time-constant method to estimate the nondominant pole that originates at the drain nodes of M₁and M₂in the CMOS folded cascade of Fig. 6.28. Assume the gates of M_1A, M_2A, M₅, M₁₁, and M₁₂are biased from low-impedance points and that a voltage drive is applied at Ï…_i. All device sizes and parameters are as given in Problem 7.40 except for M₁₁and M₁₂, which have twice the width of the other transistors. All bias currents are 100 µA except for M₅, M₁₁, and M₁₂, which have |I_D| = 200 µA. Assume V_GDof M₁₁and M₁₂is zero volts. Use C_L= 1 pF and μ_pC_ox= 30 µA/V². How much phase shift is contributed to the amplifier transfer function by this nondominant pole at the amplifier unity-gain frequency? Check your calculations with SPICE simulations.

Fig. 6.28:

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VDD УBIAS1 Mз M5 Мал Мзл Vị M2 M1 VBIAS2 VBIAS2 Мал M1A VBIAS3 УBIAS3 M12 M11 -Vss