Patent ID: 7119725
Filing Date: 2006-10-10
Classification: H03M

Abstract:
1. 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 first converting elements and at least one second converting element, generating the feedback signal corresponding to the quantized output signal to the summer, wherein the first and second converting elements form a plurality of D/A elements; 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 determines the number of groups into which the D/A elements are divided, where the number of the groups is prime to that of the first converting elements, distributes the D/A elements to each group equally, 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.