Sigma delta and multi-stage sigma delta modulation with inside loop dithering

Dithering inside the loop of sigma-delta and multistage sigma-delta modulators is studied. It is shown under certain conditions that dithering inside the loop of the sigma-delta modulator has the effect of attenuating the discrete quantization error spikes. It does not make the quantization error white. For a multistage sigma-delta modulation system, inside-the-loop dithering makes the quantization error white for a system with three stages. Simulation results are presented to support the theoretical analysis