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 2nd order sensing element to improve the SNR, whereas this paper presents a 5th order Sigma-Delta modulator to obtain higher SNR. Specifically, an additional 3rd 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 3rd order digital loop integrator are optimized by swarm intelligent algorithm. Simulation results with respect to the proposed 5th 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 5th order Sigma-Delta modulator is analyzed.