Current source calibration circuit
First Claim
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1. A current source calibration circuit comprising:
- first and second current sources;
a calibration circuit;
a clock generator to provide a clock signal having a sequence of pulses with pseudo-random periods; and
a switching circuit to pseudo-randomly coupling the first and second current sources to the calibration circuit in response to the clock signal.
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Abstract
A current source calibration circuit and methodology reduce noise generated by current switching. In one embodiment, the calibration circuit provides a random or pseudo-random clock signal to control a switching of calibration circuit. A clock signal generator has been described that provide a number of clock signals having different phases. In one embodiment, the clock signals are used to select a current source of a DAC for calibration. By using a random clock to select the current source, noise, which is generated by switching a primary current source with a backup current source, is spread out over a wider frequency range.
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Citations
18 Claims
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1. A current source calibration circuit comprising:
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first and second current sources;
a calibration circuit;
a clock generator to provide a clock signal having a sequence of pulses with pseudo-random periods; and
a switching circuit to pseudo-randomly coupling the first and second current sources to the calibration circuit in response to the clock signal. - View Dependent Claims (2, 3)
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4. A digital-to-analog (DAC) circuit comprising:
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a plurality of sub-DACs each comprising at least one current source;
a calibration circuit coupleable to calibrate the current sources; and
a clock generator circuit coupled to the calibration circuit to provide a plurality of clock signals each having a sequence of pulses with pseudo-random periods. - View Dependent Claims (5, 6, 7)
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8. A digital-to-analog (DAC) circuit comprising:
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a plurality of sub-DACs each comprising, a primary current source, a backup current source, and switching circuitry to couple the primary and backup current sources to calibration circuitry; and
a clock generator circuit coupled to the switching circuitry to provide a plurality of clock signals each having a sequence of pulses with pseudo-random periods. - View Dependent Claims (9, 10, 11)
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12. A method of calibrating a plurality of current sources comprising:
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generating a clock signal having a sequence of pulses with pseudo-random periods; and
coupling the plurality of current sources to a calibration circuit in response to the clock signal. - View Dependent Claims (13, 14, 15)
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16. A method of calibrating a digital-to-analog (DAC) converter circuit comprising:
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generating first and second clock signals each having a sequence of pulses with pseudo-random periods, wherein the first and second clock signals have different phases;
generating switching clock signals from the first and second clock signals; and
coupling current sources of the DAC to a calibration circuit in response to the switching clock signals. - View Dependent Claims (17, 18)
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Specification