Noise shapers with shared and independent filters and multiple quantizers and data converters and methods using the same
AssigneeCirrus Logic, Inc.
InventorJohn Laurence Melanson
Life of this patent
Estimating the term…
Abstract
A noise shaper including first and second quantizers and first and second feedback paths each providing feedback from a corresponding quantizer output. A loop filter system implements a plurality of transfer functions including a first non-zero transfer function between the first feedback path and an input of the first quantizer, a second non-zero transfer function between the first feedback path and an input of the second quantizer, a third non-zero transfer function between the second feedback path and the input of the first quantizer and a fourth non-zero transfer between the second feedback path and the input the second quantizer.
Claims39
A noise shaper comprising:
- first and second quantizers;
- first and second feedback paths each providing feedback from a corresponding quantizer output;
- and
- a loop filter system implementing a plurality of functions including a first non-zero transfer function between the first feedback path and an input the first quantizer, a second non-zero transfer function between the first feedback path and an input of the second quantizer, a third non-zero transfer function between the second feedback path and the input of the first quantizer and a fourth non-zero transfer function between the second feedback path and the input the second quantizer.
A noise shaper comprising:
- a loop filter including a shared filter and first and second independent filters;
- a first quantizer for generating a first quantized output signal from a first output of the loop filter, the first quantized output signal fed-back to the first independent filter;
- and
- a second quantizer for generating a second quantized output signal from a second output of the loop filter, the second quantized output signal fed-back to the second independent filter.
A delta-sigma modulator comprising:
- a plurality of quantizers for generating a plurality of quantized output signals in response to outputs from a loop filter;
- and
- a loop filter driving inputs of the plurality of quantizers, the loop filter including at least one shared filter stage receiving a sum of feedback from each of the plurality of quantizers for characterizing a global modulator noise transfer function of the quantized output signals and a plurality of independent filter stages each receiving feedback from a corresponding one of the quantizers for characterizing a local noise transfer function of a corresponding one of the quantized output signals.
A method of noise shaping comprising:
- characterizing local noise shaping of each of first and second signals with corresponding first and second independent filter sets each having at least one filter stage;
- characterizing global noise shaping of the first and second signals with a shared filter set having at least one filter stage shared by the first and second sets of independent filter stages;
- and
- independently quantizing the first and second signals with first and second quantizers.
A data conversion system for converting data from a first form to a second form comprising:
- a delta-sigma modulator for modulating an input signal comprising:
- a loop filter including a shared filter stage and a plurality of independent filter stages each sharing a signal path with the shared filter stage;
- and
- a plurality of quantizers for generating independently quantized output signals from outputs of the loop filter, an output of each quantizer fed-back to a corresponding one of the independent filter stages;
- and
- a digital to analog converter for converting the quantized outputs from the plurality of quantizers into analog.
A data conversion system comprising a delta-sigma modulator with multiple quantizers and multiple dither noise sources, wherein the sum of the dither noise sources has significantly less power than the sum of the powers of the noise sources.
A method of noise shaping comprising:
- filtering an input signal with a shared filter contributing to the inputs of each of a plurality of quantizers, a sum of outputs from the quantizers fed-back to an input of the shared filter to globally noise shape a sum of the spectrums of the outputs of the quantizers;
- and
- filtering a difference between the outputs of the quantizers with a local filter system, the filtered difference fed-back to inputs of each quantizer to locally noise shape a difference of the spectrums of the outputs of the quantizers.
Dependencies are inferred from the claim text.