Simulating nonlinear capacitors in sigma-delta modulators

Abstract

This paper addresses the simulation of switched-capacitor circuits including capacitor nonlinearities at an intermediate modelling level, filling the gap between device level and behavioural level simulators. Starting with the resolution of the trivial case of integrator with ideal components, the impact of first- and higher-order capacitor nonlinearities is analyzed in detail and the related simulation approach is explained. As an application example, the expectable performance of a simulated incremental second-order ΣΔ converter is given.