Embedded capacitor multiplier gain boosting compensation for large-capacitive-load three-stage amplifier with slew rate enhancement

Abstract

An embedded capacitor multiplier gain boosting compensation (ECMGBC) technique with slew rate enhancement circuit is presented in this paper for a three-stage amplifier. The ECMGBC technique pushes the non-dominant complex poles of the amplifier to high frequencies for gain-bandwidth product (GBW) extension under low quiescent current. In addition, the proposed slew rate enhancement circuit improves the transient responses of ECMGBC amplifier without any problem of oscillation. The ECMGBC amplifier has been designed and simulated in a 0.35-µm mixed signal CMOS process. From the post-simulation results, the amplifier driving a 1,000-pF capacitance achieves a 1-MHz GBW with a phase margin of 60° by consuming 13.5-µA quiescent current. The total compensation capacitance is only 1.2 pF. The transient responses are simulated when the amplifier is in unity-gain non-inverting configuration with a 0.6-V step input at a 2-V supply. The 1 % settling time is 1.1 µs for a 1,000-pF load capacitance. Compared with previously reported works, the ECMGBC amplifier achieves good figures of merit. Moreover, the ECMGBC amplifier obtains a very high ratio of load capacitance to total compensation capacitance.