Simultaneous SNR and SNR-variation optimization for sigma-delta modulator design

Given a loop-filter topology, a switched-capacitor sigma-delta modulator (SC-SDM) can be optimized with respect to its loop transfer function (LTF) coefficients. However, if the goal is to co-optimize signal-to-noise ratio (SNR) and SNR-variation, fast computation of both measures becomes a critical issue. In this paper a simulated-annealing (SA) based algorithm is proposed which makes use of a recently proposed fast computation method for SNR and its variance. The SNR computation method is symbolic and the computation of variation is by sensitivity. Hence, every change of the LTF coefficients can be evaluated quickly to come up with new SNR and its variation. This paper has attempted different combinations of the optimization objectives by assigning different weights to the SNR and the SNR variation. The optimization results are compared.