Efficient Simulation of Weak Nonlinearities in Continuous-Time Oversampling Converters

We propose a technique that enables the study of weak loop filter nonlinearities in a class of continuous-time delta-sigma modulators. The technique can easily be implemented in a tool intended to simulate discrete-time modulators with linear loop filters, thereby significantly reducing the simulation time. Thanks to this technique, the utility of the Schreier Delta-Sigma toolbox can be extended to include weakly nonlinear effects in the loop filter, thus enabling the architectural exploration of alternate loop filter and operational amplifier (opamp) topologies. The results from the use of our technique are compared to those obtained using a circuit simulator, and good agreement is seen.