AC boosting compensation scheme for low-power multistage amplifiers

A new power-efficient frequency compensation scheme is proposed, called the AC Boosting Compensation (ACBC) scheme. An ac path is added to the internal stage of the conventional multistage amplifier, which improves significantly the performance such as the gain-bandwidth product and the slew rate without increasing the total power consumption. Analysis shows that the stability can be perfectly ensured. Two three-stage amplifiers have been implemented with and without a feed-forward stage, and fabricated in a 0.35-/spl mu/m CMOS process. The ACBC amplifiers driving a 500-pF capacitance achieved 1.9-MHz gain-bandwidth product (GBW) dissipating only 0.3-mW power with a 2-V supply. An amplifier based on conventional nested Miller compensation (NMC) could only achieve 0.11-MHz GBW with the same load and power conditions, which shows an improvement of a factor of 17 in GBW.