Nonlinear settling behavior in oversampled converters

Abstract

We present a new analytical model for opamp induced nonlinearity in oversampled converters. This model incorporates both finite slew rate and finite gain bandwidth effects and is valid for both first order and higher order modulators. Theoretical predictions agree very well with measured results from fabricated ICs. The model consists only of circuit design parameters, and can be utilized to explore design tradeoffs and optimize converter performance. For our design the use of our model resulted in a 40% reduction in power consumption without loss of performance.