Low-power oscillator
First Claim
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1. An integrated oscillator circuit comprising:
- an oscillator configured to be switched between a first frequency and a second frequency;
switching circuitry configured to receive an input representative of a target frequency and to switch the oscillator between the first and second frequencies at intervals determined by the input so as to cause the average output frequency of the oscillator to approximate the target frequency; and
circuitry for calibrating the oscillator against a reference clock,wherein the integrated oscillator circuit is configured to output a clock signal derived from a crystal oscillator while said oscillator is being calibrated, and to output a clock signal derived from said oscillator when the integrated oscillator circuit is not being calibrated.
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Abstract
An integrated oscillator circuit comprises an oscillator configured to be switched between a first frequency and a second frequency. A switching circuit receives an input representing a target frequency and switches the oscillator between the first and second frequencies at intervals determined by the input, so as to cause the average output frequency of the oscillator to approximate the target frequency.
7 Citations
33 Claims
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1. An integrated oscillator circuit comprising:
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an oscillator configured to be switched between a first frequency and a second frequency; switching circuitry configured to receive an input representative of a target frequency and to switch the oscillator between the first and second frequencies at intervals determined by the input so as to cause the average output frequency of the oscillator to approximate the target frequency; and circuitry for calibrating the oscillator against a reference clock, wherein the integrated oscillator circuit is configured to output a clock signal derived from a crystal oscillator while said oscillator is being calibrated, and to output a clock signal derived from said oscillator when the integrated oscillator circuit is not being calibrated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of operating an integrated oscillator circuit, wherein the circuit comprises an oscillator configured to be switched between a first frequency and a second frequency, the method comprising:
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receiving an input representative of a target frequency; switching the oscillator between the first and second frequencies at intervals determined by the target frequency so as to cause the average output frequency of the oscillator to approximate the target frequency; calibrating the oscillator against a reference clock; outputting a clock signal derived from a crystal oscillator during said calibration; and outputting a clock signal derived from said oscillator while the circuit is not being calibrated. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification