Correction of nonlinear output distortion in a Delta Sigma DAC
AssigneeAudioLogic, Inc.
InventorJohn Laurence Melanson
Life of this patent
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Abstract
A delta sigma modulator of at least second order includes correction means applied to each feedback loop in the modulator, to account for systemic nonlinear output distortions. Since the output distortion is nonlinear, the correction applied to each feedback loop is nontrivially different. Such a corrected delta sigma modulator may be used in a demodulator including an output digital to analog converter (DAC) to account for systemic imperfections in the pulses formed by the DAC. The corrected delta sigma modulator is also useful in correcting output errors associated with high quality multilevel demodulators and class D power amplifiers. The corrected delta sigma modulator may be one bit or multilevel.
Claims13
A compensated delta sigma modulator of at least second order, having at least first and second feedback loops carrying an original feedback signal and further comprising:
- means for selecting a first corrected feedback, based upon the original feedback, to be applied to the first feedback loop;
- means for applying the first corrected feedback to the first feedback loop;
- means for selecting a second corrected feedback, based upon the original feedback, to be applied to the second feedback loop;
- and
- means for applying the second corrected feedback to the second feedback loop;
- wherein the first corrected feedback is nontrivially different from the second corrected feedback.
A demodulator comprising:
- a compensated delta sigma modulator of at least second order, having at least first and second feedback loops carrying an original feedback signal and further comprising:
- means for selecting a first corrected feedback, based upon the original feedback, to be applied to the first feedback loop;
- means for applying the first corrected feedback to the first feedback loop;
- means for selecting a second corrected feedback, based upon the original feedback, to be applied to the second feedback loop;
- and
- means for applying the second corrected feedback to the second feedback loop;
- wherein the first corrected feedback is nontrivially different from the second corrected feedback;
- and
- a digital to analog converter connected to the output of the modulator for generating an analog output.
A high quality digital to analog converter comprising:
- a compensated multilevel delta sigma modulator of at least second order, having at least first and second feedback loops carrying an original feedback signal and outputting a multilevel output signal and further including:
- means for selecting a first corrected feedback, based upon the original feedback, to be applied to the first feedback loop,
- means for applying the first corrected feedback to the first feedback loop,
- means for selecting a second corrected feedback, based upon the original feedback, to be applied to the second feedback loop, and
- means for applying the second corrected feedback to the second feedback loop;
- wherein the first corrected feedback is nontrivially different from the second corrected feedback;
- and
- a pattern generator connected to the output of the modulator, including means for generating a plurality of two level output signals having patterns based upon the multilevel output of the modulator.
A class D output power amplifier comprising:
- a compensated delta sigma modulator of at least second order, having at least first and second feedback loops
- carrying an original feedback signal and outputting an output signal and further including:
- means for selecting a first corrected feedback to be applied to the first feedback loop,
- means for applying the first corrected feedback to the first feedback loop,
- means for selecting a second corrected feedback, to be applied to the second feedback loop, and
- means for applying the second corrected feedback to the second feedback loop;
- wherein the first corrected feedback is nontrivially different from the second corrected feedback;
- and
- a pulse wave modulator digital to analog converter connected to the output of the compensated delta sigma modulator for generating two analog signals P and N based on the output signal from the compensated delta sigma modulator.
Dependencies are inferred from the claim text.