A new mixed stable DEM algorithm for bandpass multibit delta sigma ADC

Abstract

A multibit delta-sigma modulator (DSM) is an attractive way of realizing a high-accuracy, high-speed, and low power data converter. However, the overall resolution of delta-sigma modulators is limited by the internal digital-to-analog converter (DAC) nonlinearity that is normally caused by mismatching errors while realizing. Recently, some dynamic element matching (DEM) methods were proposed for reducing mismatch errors by spectral shaping of its naturally white spectrum, but almost all higher order DEM have serious problems of instability and hardware complexity. This paper presents a new more stable algorithm mixed of third and second order mismatch noise shaping. Simulation results show the considerably improving of inband noise shaping, stability and hardware complexity for a third order 17-level bandpass DSM. The proposed technique can also be used in lowpass DSM and extended number of quantization DAC level.