Design of Operational Amplifier for Pipelined Analog to Digital Converter

Abstract

This work presents the design of operational amplifier in UMC 0.18um technology using Cadence tool.The circuit is to be used in pipelined Analog to Digital Converter.Operational amplifier plays an important role in designing the ADC because it is the op ampwhich decides the conversion rate and power consumption of complete ADC.A single ended or fully differential op amp can be used in the multiplying digital analog converter(MDAC) unit.It is the architecture of the ADC which decides which po amp is to be used in it.In this specific application of ADC which is 8-bits pipelined ADC with 1-bit per stag architecture,there was a need of two different op amps.One was required for the basic MDAC unit and other for the unity gain configuration.Both op amps have been designed for the specific application.The specifications of both op amps were decided after studying the complete architecture of ADC.Four types of op amps i.e. simple two stage,telescopic,folded cascode and gain boosted architectures have been studied and designed step by step in this thesis.Simple two stage and telescopic amplifier have been implemented in single ended as well fully differential configuration.Folded cascode and folded cascode with gain boosted technique have been designed in fully differential configuration.The designs with best performance of gain,UGB,power and settling time have been used in the pipelined ADC as final designs.