Skip to Main Content
This paper addresses the design of sigma-delta modulators with arbitrary signal and noise transfer functions by presenting a genetic algorithm (GA) based search method. The objective function is defined to include the difference D between the magnitude of the frequency responses of the designed transfer functions and the ideal one, the quantizer gain λcritical for which the poles of the modulator start moving out of the unit circle, and the spread of the coefficients S. Stability can be improved by reducing λcritical while a smaller S reduces the implementation complexity. A genetic algorithm (GA) searches for poles/zeros of the transfer functions to minimize the objective function D+w1*λcritical+w2*S, where w1 and w2 are two weighing factors. Numerical results demonstrate the effectiveness of the proposed method.