A new op-amp noise model for switched-capacitor sigma-delta modulator in SIMULINK

Precise behavioral models are needed to simulate switched-capacitor sigma-delta modulators more efficiently. This paper presents a new noise model of the operational amplifier (op-amp) used in a typical correlated double sampling (CDS) integrator. Evaluation and validation of the new model are done via behavioral and transistor-level simulations for a 2-1 MASH modulator using SIMULINK and SPECTRE with 0.35um CMOS technology. Two sets of results for comparison are obtained and the biggest difference between the two simulators is around 2dB.