Simulation of multi-bit digital delta-sigma modulator

The paper describes a four-order delta-sigma modulation (DSM) with 15 levels quantizer which is used in a 24-bit 44.1-kHz sample-rate audio digital-to-analog converter (DAC). An odd level quantizer has been chosen instead of an even level to reduce quantization noise. The noise transfer function (NTF) is designed to have the zeros optimally in order to increase DR. The peak SNR of the DSM is about 130dB, which is enough for an audio DAC designed with a 0.35 um CMOS technology.