Three-stage nested-Miller-compensated operational amplifiers: Analysis, design, and optimization based on settling time

In analog signal-processing applications, settling performance of the employed operational amplifiers (opamps) is usually of great matter. Under low-voltage environment of modern technologies where only a few transistors are allowed to be stacked, three-stage amplifiers are gaining more interest. Unfortunately, design and optimization of three-stage opamps based on settling time still suffer from lack of a comprehensive analysis of the settling behavior and closed-form relations between settling time/error and other parameters. In this paper, a thorough analysis of the settling response of three-stage nested-Miller-compensated opamps, including linear and non-linear sections, is presented. This analysis leads to a design methodology which determines the circuit requirements for desired settling time/error. Based on settling time, it allows optimizations in power consumption and area. Copyright © 2010 John Wiley & Sons, Ltd.