Design Procedure for Three-Stage CMOS OTAs with AC Boosting Frequency Compensation Technique

Abstract

ABSTRACTAn analytic design guide to design a three-stage cascade CMOS operational amplifier compensated by AC boosting frequency compensation (ACBC) method is presented in this paper. The procedure allows electrical parameters such as gain bandwidth (GBW) product or phase margin to be related to the value of circuit elements such as aspect ratio or biasing currents of transistors. The presented design guide is suited for pencil-and-paper design and yields accurate performance without unnecessary circuit constraint introduction. Simulation results using TSMC 0.18 µm CMOS process verifies accuracy and robustness of proposed procedure. Various load capacitors and circuit conditions are simulated and, based on obtained results, the presented design guide is comprehensive and efficient since it leads us from frequency response parameters to aspect ratio of MOSFETs.