Designing and Optimizing of Sigma-Delta Modulator Using PSO Algorithm

A self-adaptive Sigma-Delta modulator, which offers opportunity to simplify the process of tuning parameters and further improve the noise performance, is presented in this paper. Traditional Sigma-Delta modulator mainly focused on using a 2^nd order sensing element to improve the SNR, whereas this paper presents a 5^th order Sigma-Delta modulator to obtain higher SNR. Specifically, an additional 3^rd order digital loop integrator is inserted between the AFE and the quantizer, which increases overall loop order to produce much higher SNR for Sigma-Delta modulator and the parameters of the 3^rd order digital loop integrator are optimized by swarm intelligent algorithm. Simulation results with respect to the proposed 5^th order Sigma-Delta modulator, SNR >122 dB and the noise floor under -170dB are obtained in frequency range of [5-150Hz]. In further simulation, the robustness of the proposed 5^th order Sigma-Delta modulator is analyzed.