Suppression of noise of delta-sigma modulators
AssigneeCirrus Logic, Inc.
InventorsLeyi YiN, John L. Melanson, Wai-Shun Shum, Xiaofan Fei
Life of this patent
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Abstract
A delta-sigma modulator may include a loop filter having a loop filter input configured to receive an input signal and generate an intermediate signal responsive to the input signal and a near-zero asymmetric quantizer configured to quantize the intermediate signal into a quantized output signal which is fed back as an input to the loop filter such that the quantized output signal has a plurality of quantization levels, wherein the plurality of quantization levels are asymmetric to zero.
Claims20
A delta-sigma modulator comprising:
- a loop filter having a loop filter input configured to receive an input signal and generate an intermediate signal responsive to the input signal;
- and
- a near-zero asymmetric quantizer configured to quantize the intermediate signal into a quantized output signal which is fed back as an input to the loop filter such that the quantized output signal has a plurality of quantization levels, wherein the plurality of quantization levels are asymmetric to zero.
A delta-sigma modulator comprising:
- a loop filter having a loop filter input configured to receive an input signal and generate an intermediate signal responsive to the input signal, wherein the loop filter comprises one or more integrator stages comprising a first integrator stage;
- a quantizer configured to quantize the intermediate signal into a quantized output signal which is fed back as an input to the loop filter such that the quantized output signal has a plurality of quantization levels;
- and
- a biasing block configured to:
- calculate a fractional part of a state variable associated with the first integrator stage;
- determine if the fractional part has a desired value;
- and
- responsive to the fractional part being outside of the desired value, actively bias the state variable to cause the fractional part to have the desired value in order to cause the delta-sigma modulator to have a desired noise profile.
A method comprising:
- generating, with a loop filter, an intermediate signal responsive to an input signal to the loop filter;
- and
- quantizing, with a near-zero asymmetric quantizer, the intermediate signal into a quantized output signal which is fed back as an input to the loop filter such that the quantized output signal has a plurality of quantization levels, wherein the plurality of quantization levels are asymmetric to zero.
A method comprising:
- generating, with a loop filter comprising one or more integrator stages comprising a first integrator stage, an intermediate signal responsive to an input signal to the loop filter;
- quantizing, with a quantizer, the intermediate signal into a quantized output signal which is fed back as an input to the loop filter such that the quantized output signal has a plurality of quantization levels;
- calculating a fractional part of a state variable associated with the first integrator stage;
- determining if the fractional part has a desired value;
- and
- responsive to the fractional part being outside of the desired value, actively biasing the state variable to cause the fractional part to have the desired value in order to cause the delta-sigma modulator to have a desired noise profile.
Dependencies are inferred from the claim text.