Robust to PVT enhanced DC gain amplifier using no Miller capacitor feedforward compensation

Abstract

This paper presents an operational transconductance amplifier compensated in frequency with a feedforward path implemented with current mirrors. This concept eliminates the need of Miller capacitor and improves performance compared to traditional feedforward topologies in regard to DC gain. Gain enhancement is achieved because of the use of current mirrors which reduces the number of the conductances that are connected to the output and increasing output impedance. Moreover, common mode range is improved by the PMOS differential pair used in the feedforward stage. Simulations results for the designed circuit on the typical UMC 180 nm CMOS process, show a DC gain above 60 dB with a unity gain frequency of 511 MHz, a phase margin (PM) of 49 , a slew rate (SR) of 205 V/ls and a power consumption of 5.1 mW maintaining low variations in regard to process, voltage and temperature variations.