Error feedback structure for delta-sigma modulators with improved stability
AssigneeBroadcom Corporation
InventorMinsheng Wang
Life of this patent
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Abstract
An error feedback circuit includes a first summer receiving an analog input signal and a feedback signal and outputting a summed signal. A quantizer receives the summed signal and outputs a quantized output signal. A limiter receives the summed signal and outputs a limited summed signal. The limiter limits the limited summed signal to α* (maximum value of input signal), α>1. A second summer receives the limited summed signal and the output signal and outputs an error signal. A filter receives the error signal and outputting the feedback signal. Typically, 1.0<α<2.0, more preferably 1.4<α<1.6. The filter has a transfer function of H1(z)=2z−1−z−2.
Claims4
A method for improving stability of delta-sigma modulation process, comprising:
- (a) receiving an analog input signal and a feedback signal;
- (b) summing the received analog and feedback signal to produce a summed signal, wherein the summed signal is limited such that the absolute value of a limited summed signal has the value α*(maximum value of the input signal), α>1;
- (c) quantizing the summed signal and outputting a quantized output signal;
- (d) generating an error signal by summing the limited summed signal and the quantized output signal,
- and
- (e) performing second order filtering of the error signal to produce the feedback signal.
Dependencies are inferred from the claim text.