| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for operating a sigma-delta modulator of a type that includes a loop filter followed by a quantizer, and to provide a sigma- delta modulator operated according to this method. SOLUTION: The method includes steps of (a) sampling an amplitude of an input signal to the loop filter (12); and (b) generating a dither current signal for summation with a quantizer current signal, where the dither current signal is generated to have a pseudo random amplitude that is modulated so as to be inversely proportional to the sampled amplitude of the input signal. The step of generating operates at least one linear feedback shift register to control the on and off states of a plurality of current sources forming a DAC and, hence, the amplitude of the dither current signal, and may further select the polarity of the dither current signal.
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