Patent ID: 7183955

Claim:
A sigma-delta modulator, comprising: a summer receiving an analog input signal and a feedback signal generating an error signal corresponding to a difference between the analog input signal and the feedback signal; a loop filter coupled to the summer, receiving the error signal to generate a filtered signal; a quantizer coupled to the loop filter, converting the filtered signal to a quantized output signal; a D/A (digital-to-analog) converter coupled to the summer, comprising a plurality of D/A elements generating the feedback signal corresponding to the quantized output signal to the summer with selected D/A elements thereof; and a dynamic element matching logic coupled between the quantizer and the D/A converter, receiving the quantized output signal and selecting the D/A elements of the D/A converter, wherein the dynamic element matching logic divides the D/A elements into a plurality of groups, where the number of the groups is prime to that of the D/A elements, and selects the groups and D/A elements thereof according to the quantized output signal and a previous selection of groups and D/A elements.