A novel noise-shaping DAC for multi-bit sigma-delta modulator

This paper describes a new noise-shaping technique for reducing the noise of the internal digital-analog conversion (DAC) in multi-bit low-pass sigma-delta modulators. The proposed technique works with most existing dynamic element matching (DEM) algorithms to provide noise shaping to the DAC noise. The simulation shows that a 10-dB improvement in the signal-to-noise conversion ratio can be obtained with the proposed noise-shaping with DEM (NSDEM) technique. A dithered DAC employing NSDEM is realized in a 0.35-μm CMOS process and the test result shows the first-order high-pass noise shaping to the DAC noise, and validates the proposed concept.