Patent ID: 7486214

Claim:
A sigma-delta modulator circuit, comprising: a filtering portion having a first input coupled to receive an input signal, an output configured to provide a filtered output signal, and a second input coupled to receive a feedback signal based on the filtered output signal; a first switching device coupled to the first input and coupled to receive an input signal for modulation; and a second switching device coupled to the second input and coupled to receive the feedback signal, wherein the first and second switching devices are configured to receive control signals such that, in an operating mode, the first switching device is to provide the input signal for modulation to the first input, and the second switching device is to provide the feedback signal based on the filtered output signal to the second input, and in a tuning mode, the first switching device is to prevent the input signal from being applied to the first input, and the second switching device is configured to apply a stimulus signal to the second input.