Improvement of frequency performance of fully differential operational amplifier for switched-capacitor application

Abstract

In recent years, switched-capacitor (SC) structure has been widely used in many electronic fields, such as analog to digital converter (ADC) and digital to analog converter (DAC). The vital part in the SC structure is operational amplifier (Op-Amp), to improve the performance of SC structure, a good operational amplifier is necessary. In this paper, based on 0.18µm process, we proposed two types of differential Op-Amps: traditional differential structure and fully differential telescopic structure. Aiming to realize better frequency performance, we compared this two types and find out the telescopic structure has much better unity gain bandwidth (UGBW) up to 690MHz with similar small signal gain and phase margin.