Dithering effect simulation for sigma-delta modulators with the presence of thermal noise

This paper presents an efficient and accurate method for computer simulation of the dithering effects in breaking up tone structures in analog oversampled sigma-delta modulators. The simulation is at macro-model level, where comparators, operational amplifiers, resistors, inductors, switches, capacitors and linear controlled sources are used as building blocks. The dithering effect simulation algorithm, as well as the thermal noise simulation algorithm, has been implemented in a computer program. It can be used to study dithering effects in switch-capacitor and continuous-time sigma-delta modulators, with or without the presence of thermal noise. Simulation examples of a switch-capacitor sigma-delta modulator and a continuous-time sigma-delta modulator are given