Design of a fully differential controlled gain open-loop wideband amplifier with high PSRR

Abstract

Fully differential amplifier has a superior ability of noise immunity. It has been widely used in audio, data transmission, and telephone systems. This project involves the design of a fully differential controlled-gain open-loop wideband amplifier with high PSR on 55nm CMOS technology. The fully differential wideband amplifier maintains the common mode output voltage at 0.6V through a common-mode feedback circuit. The 1.2V voltage supply voltage has a power dissipation of 0.573mW under DC operation. The design achieved a controlled open-loop voltage gain of 12.399dB, with a unity gain bandwidth of 557 MHz, with a load of 100fF on each output. The output voltage can provide a swing from 0.152V to 1.074V. The total harmonic distortion of – 46.6 dB for 50mV differential input signals. The wideband amplifier is capable of CMR (single-ended) = -53.53dB, PSR (single-ended) = -41.34dB when common-mode signal is injected from input and the respective supply. The total layout area is 80μm x 35μm for the implementation of all the required devices.