Optimal design of op amps for oversampled converters

Abstract

The power consumption for various op amps used in /spl Sigma//spl Delta/ modulators is considered. We first classify the different op amp topologies used in such modulators. We then develop a generalized integrator model that allows us to compare the power consumption for all these topologies. We also derive an expression for the minimum theoretical bound on the power dissipation. We illustrate our results with two design examples: a class A and a class AB op amp. It is shown that class A op amps are the best choice for /spl Sigma//spl Delta/ modulators.