Study on Delta Sigma DA Modulator Performance Improvement Using Digital Dither

Abstract

A ΔΣDA modulator suffers from a limit cycle problem when its input amplitude is very small, and here we propose a digital dither method to solve this problem. It uses an XOR gate at the modulator output; one of its input is the comparator output (digital integrator MSB) and the other output is the digital dither generated by another ΔΣ digital modulator. Our simulation results with MATLAB and RTL have verified the effectiveness of the proposed method.