Ultra-Wide Bandwidth Fully Differential CMOS Opamp with a Novel Bandwidth Extension Technique for SoC Active Filter Applications

Abstract

An ultra-wide bandwidth fully differential two-stage 65nm CMOS operational amplifier (Opamp) is presented, which uses a novel bandwidth extension technique called pole duplication. This technique is based on relocating the dominant pole with the same location with a non-dominant pole and adjusting 3-dB frequency and stability with a compensation network. Simulation results show that the proposed Opamp has 103MHz 3-dB bandwidth with a 2pF load capacitor. It consumes 9mA current from 1.2-V supply. Transition frequency of 2.4GHz and a gain of 29dB is accomplished. A 2pF load capacitance can be driven at a phase margin of 55 degrees. The suggested pole duplication technique is used to achieve higher 3-dB cut-off frequencies by adjusting the load capacitor. Fully differential two-stage Opamp is presented, which uses a novel bandwidth extension technique, is suitable for SoC active filter applications with 40 mu mx60 mu m layout area and ultra-wide 3-dB bandwidth.