17.3 A 0.9V 6.3μW multistage amplifier driving 500pF capacitive load with 1.34MHz GBW

As process scales down, low-voltage, low-power, multistage amplifiers capable of driving a large capacitive load with wide bandwidth are becoming more important for various applications. The conventional frequency compensation methods, however, are based on cumbersome transfer function derivations or complicated local loop analysis [1]-[3], inhibiting intuitive understanding. An approach is presented in this paper, which generates insight for the poles and zeros through distinctive compensation analysis, and is applicable to large-number-stage amplifiers. The approach applies feedback theory and simplifies high-frequency Miller amplifiers, thereby reducing orders of circuits and improving insight.