Understanding weak loop filter nonlinearities in continuous time ΔΣ converters

We propose a technique that enables a designer to study the effect of weak loop filter nonlinearities in a class of continuous-time delta-sigma modulators. Thanks to this technique, the utility of the Schreier Delta-Sigma Toolbox can be extended to include weakly nonlinear effects, enabling the architectural exploration of alternate loop filter and opamp topologies. The results from the use of our technique are compared to those obtained using a circuit simulator, and good agreement is seen.