Methods for output edge-balancing in pulse width modulation systems and data converters using the same
First Claim
Patent Images
1. A method of performing digital to analog conversion comprising:
- generating a pulse width modulated data stream and another pulse width modulated data stream including generating encoding patterns of the pulse width modulated data stream by selectively generating early and late pattern edges relative to edges of a reference such that the encoding patterns of the pulse width modulated data stream minimize distortion in the another pulse width modulated stream caused by edges in the pulse width modulated data stream, and wherein selectively generating early and late pattern edges comprises;
tracking a number of early and late edges generated in previously generated encoding patterns; and
selectively generating a late or early edge in at least one subsequent encoding pattern such that an average number of early edges in the pulse width modulated data stream approximates an average number of late edges in the pulse width modulated data stream;
converting in corresponding digital to analog conversion elements the pulse width modulated data stream and the another pulse width modulated data stream into an analog signal and another analog signal; and
summing the analog signal and the another analog signal to generate an output signal.
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Abstract
A method of performing digital to analog conversion includes generating a pulse width modulated data stream and another pulse width modulated data stream, encoding patterns of the pulse width modulated data stream selected to minimize distortion in the another pulse width modulated stream caused by edges in the pulse width modulated data stream. The pulse width modulated data stream and the another pulse width modulated data stream are converted into an analog signal and another analog signal converting in corresponding digital to analog conversion elements and the analog signal and the another analog signal are summed to generate an analog output signal.
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Citations
17 Claims
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1. A method of performing digital to analog conversion comprising:
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generating a pulse width modulated data stream and another pulse width modulated data stream including generating encoding patterns of the pulse width modulated data stream by selectively generating early and late pattern edges relative to edges of a reference such that the encoding patterns of the pulse width modulated data stream minimize distortion in the another pulse width modulated stream caused by edges in the pulse width modulated data stream, and wherein selectively generating early and late pattern edges comprises; tracking a number of early and late edges generated in previously generated encoding patterns; and selectively generating a late or early edge in at least one subsequent encoding pattern such that an average number of early edges in the pulse width modulated data stream approximates an average number of late edges in the pulse width modulated data stream; converting in corresponding digital to analog conversion elements the pulse width modulated data stream and the another pulse width modulated data stream into an analog signal and another analog signal; and summing the analog signal and the another analog signal to generate an output signal. - View Dependent Claims (2, 3)
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4. A method of performing digital to analog conversion comprising:
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generating a pulse width modulated data stream and another pulse width modulated data stream including generating encoding patterns of the pulse width modulated data stream by selectively generating early and late pattern edges relative to edges of a reference pattern such that the encoding patterns of the pulse width modulated data stream minimize distortion in the another pulse width modulated stream caused by edges in the pulse width modulated data stream, wherein selectively generating early and late pattern edges comprises; varying a count in a counter from a neutral count value in response to a late or early edge in selected encoding patterns generated; and generating a late or early edge in a subsequent encoding pattern which varies the count in the counter towards the neutral count value; converting in corresponding digital to analog conversion elements the pulse width modulated data stream and the another pulse width modulated data stream into an analog signal and another analog signal; and summing the analog signal and the another analog signal to generate an output signal.
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5. A method of performing digital to analog conversion comprising:
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generating a pulse width modulated data stream and another pulse width modulated data stream including generating encoding patterns of the pulse width modulated data stream by selectively generating early and late pattern edges relative to edges of a reference pattern such that the encoding patterns of the pulse width modulated data stream minimize distortion in the another pulse width modulated stream caused by edges in the pulse width modulated data stream, wherein a number of early pattern edges is approximately equal to a number of late pattern edges generated in the pulse width modulated data stream; converting in corresponding digital to analog conversion elements the pulse width modulated data stream and the another pulse width modulated data stream into an analog signal and another analog signal; and summing the analog signal and the another analog signal to generate an output signal.
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6. A method of performing digital to analog conversion comprising:
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generating a pulse width modulated data stream and another pulse width modulated data stream including generating encoding patterns of the pulse width modulated data stream by selectively generating early and late pattern edges relative to edges of a reference pattern such that the encoding patterns of the pulse width modulated data stream minimize distortion in the another pulse width modulated stream caused by edges in the pulse width modulated data stream, wherein a number of late pattern edges substantially exceeds a number of early pattern edges generated in the pulse width modulated data stream; converting in corresponding digital to analog conversion elements the pulse width modulated data stream and the another pulse width modulated data stream into an analog signal and another analog signal; and summing the analog signal and the another analog signal to generate an output signal.
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7. A digital to analog conversion system comprising:
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pulse width modulation circuitry for generating first and second pulse width modulated data streams, encoding patterns of the first pulse width modulated data stream selected to minimize distortion in the second pulse width modulated stream caused by edges in the first pulse width modulated data stream and wherein the pulse width modulation circuitry generates the encoding patterns of the first data stream by generating early and late pattern edges relative to edges of a reference pattern and is operable to track a number of early and late edges generated in previously generated encoding patterns in the first pulse width modulated data streams and selectively generate a late or early edge in at least one subsequent encoding pattern in the first pulse width modulated data stream such that an average number of early edges approximates an average number of late edges; first and second digital to analog conversion elements for respectively converting the first and second the first and second analog signals to generate the analog output signal. - View Dependent Claims (8, 9, 10)
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11. A digital to analog conversion system comprising:
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pulse width modulation circuitry for generating first and second pulse width modulated data streams, encoding patterns of the first pulse width modulated data stream selected to minimize distortion in the second pulse width modulated stream caused by edges in the first pulse width modulated data stream and wherein the pulse width modulation circuitry generates the encoding patterns of the first data stream by generating early and late pattern edges relative to edges of a reference pattern and comprises; a counter counting from a neutral count value in response to a late or early edge in selected encoding patterns generated in the first pulse width modulated stream; and circuitry causing generation of a late or early edge in a subsequent encoding pattern which varies the count in the counter towards the neutral count value; and first and second digital to analog conversion elements for respectively converting the first and second the first and second analog signals to generate the analog output signal. - View Dependent Claims (12)
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13. An digital to analog conversion system comprising:
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a noise shaper for requantizing a digital input data stream; pulse width modulation circuitry for generating first and second pulse width modulated data streams in response to the output of the noise shaper, encoding patterns of the first pulse width modulated data stream selected to minimize distortion in the second pulse width modulated stream caused by edges in the first pulse width modulated data stream, and wherein the pulse width modulation circuit generates the encoding patterns of the first data stream by generating early and late pattern edges relative to edges of a reference pattern and is operable to; track a number of early and late edges generated in previously generated encoding patterns in the first pulse width modulated data stream; and selectively generate a late or early edge in at least one subsequent encoding pattern in the first pulse width modulated data stream such that an average number of early edges approximates an average number of late edges; and first and second digital to analog conversion elements for respectively converting the first and second pulse width modulated data streams into first and second analog signals; and an analog summer for summing the first and second analog signals to generate the analog output signal. - View Dependent Claims (14, 15, 16, 17)
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Specification