Digital-to-analog converter with improved performance and method therefor
First Claim
Patent Images
1. A digital-to-analog converter with improved performance comprising:
- a scaler having an input coupled for receiving a first digital signal, and an output for providing said first digital signal scaled by a predetermined amount;
a sigma-delta modulator having an input coupled to said scaler, and an output for providing a second digital signal; and
an analog summing network having inputs for receiving respective bits of said second digital signal, and an output for providing an analog signal of the digital-to-analog converter;
said predetermined amount greater than or equal to a loss of dynamic range of said sigma-delta modulator.
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Abstract
A digital-to-analog converter (20) with improved performance includes an offset/scaler (23), a sigma-delta modulator (25), and an analog summing network (26). In one embodiment, the offset/scaler (23) scales an input signal by a predetermined amount, such as three-quarters, to compensate for nonlinearities in a transfer characteristic of the sigma-delta modulator (25). In another embodiment, the sigma-delta modulator (25) is a sufficiently-resolved sigma-delta modulator. The offset/scaler (23) provides an offset to the sufficiently-resolved sigma-delta modulator (25) sufficient to force a coarse bit thereof into an idle pattern.
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Citations
14 Claims
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1. A digital-to-analog converter with improved performance comprising:
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a scaler having an input coupled for receiving a first digital signal, and an output for providing said first digital signal scaled by a predetermined amount; a sigma-delta modulator having an input coupled to said scaler, and an output for providing a second digital signal; and an analog summing network having inputs for receiving respective bits of said second digital signal, and an output for providing an analog signal of the digital-to-analog converter; said predetermined amount greater than or equal to a loss of dynamic range of said sigma-delta modulator. - View Dependent Claims (2, 3)
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4. A digital-to-analog converter with improved performance comprising:
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an offset circuit having an input for receiving a first digital signal, and an output for providing a second digital signal, said second digital signal offset by a predetermined amount from said first digital signal; a sigma-delta modulator having an input for receiving said second digital signal, and an output for providing a third digital signal; and an analog summing network having inputs for receiving respective ones of a plurality of bits of said third digital signal, and an output for providing an analog output signal of the digital-to-analog converter; said sigma-delta modulator characterized as being a sufficiently-resolved sigma-delta modulator; said predetermined amount sufficient to ensure that a coarse bit of said sigma-delta modulator goes into an idle pattern. - View Dependent Claims (5, 6, 7, 8)
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9. A method of improving performance of a digital-to-analog converter comprising the steps of:
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receiving a first digital signal at an input of said digital-to-analog converter; adding said first digital signal to one-half of said first digital signal to provide a second digital signal; left-shifting said second digital signal to provide a third digital signal; providing said third digital signal to an input of a sigma-delta modulator; coupling an output of said sigma-delta modulator to an input of an analog summing network; providing an output of said analog summing network as an output of said digital-to-analog converter. - View Dependent Claims (10, 11, 12)
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13. A digital-to-analog converter with improved performance comprising:
- input means for receiving a first digital signal;
an offset/scaler having an input coupled to said input means, and an output, for offsetting said digital signal by a first predetermined amount and for scaling said digital signal by a second predetermined amount to provide a second digital signal at said output; a sigma-delta modulator having an input coupled to said output of said offset/scaler, and an output for providing a third digital signal; and an analog summing network having an input for receiving said third digital signal, and an output for providing an analog output signal of the digital-to-analog converter; said sigma-delta modulator characterized as being a sufficiently-resolved sigma-delta modulator; said first predetermined amount greater than or equal to a loss of dynamic range of said sigma-delta modulator; said second predetermined amount insuring a coarse bit of said sigma-delta modulator goes into an idle pattern. - View Dependent Claims (14)
- input means for receiving a first digital signal;
Specification