An Elaborate Design and Optimization of Low Order Bandpass Sigma-Delta Modulator

This paper presents an elaborate plan and optimization method for designing and implementing low-order band pass digital sigma-delta modulator with high order output dynamic range (DR). The noise suppression in the pass band region of the modulator and high order output DR would be achieved by designing and optimizing the Noise Transfer Function (NTF) based on over sampling ratio (OSR) and desired modulator operational frequency and designing the Signal Transfer Function (STF) by the mean which the optimum gain in desired frequency would be acquired. Designed and optimized modulator has been implemented completely on digital circuits and it would be shown that the first order designed modulator has the output dynamic range of 90dB which corresponds to 15 bits data conversion. Results from various simulations illustrate both the stability and high performance of the design and flexibility of the overall structure.