Temperature compensated crystal oscillator
First Claim
1. A temperature-compensated oscillator comprising:
- a crystal oscillator outputting a reference clock;
a phase locked loop (PLL) receiving the reference clock and outputting a phase locked clock waveform;
a temperature sensor outputting a voltage corresponding to a temperature of the crystal oscillator;
wherein the voltage is used by the PLL to temperature-compensate the phase locked clock waveform.
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Accused Products
Abstract
An environmental-compensated oscillator includes a reference clock waveform generator; a phase locked loop receiving the reference clock waveform and outputting a phase locked clock waveform; and a sensor outputting a voltage corresponding to an environmental parameter of the generator. The voltage is used by the PLL to compensate the phase locked clock waveform. The PLL includes a phase detector, a charge pump coupled to an output of the phase detector, a low pass filter coupled to an output of the charge pump, a voltage controlled oscillator (“VCO”) coupled to an output of the low pass filter, and a feedback path coupled between an output of the VCO and the phase detector, wherein the feedback path includes a phase rotator capable of fine tuning an output frequency of the VCO responsive to a frequency of an input clock. An accumulator is coupled to the phase rotator and supplies the input clock to the phase rotator. The phase rotator finely tunes the VCO output frequency. An analog-to-digital converter converts the voltage to a digital representation. The digital representation is mapped to a frequency adjustment for use by the PLL for the compensation. The environmental parameter is any of temperature, stress and power supply voltage.
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Citations
18 Claims
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1. A temperature-compensated oscillator comprising:
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a crystal oscillator outputting a reference clock;
a phase locked loop (PLL) receiving the reference clock and outputting a phase locked clock waveform;
a temperature sensor outputting a voltage corresponding to a temperature of the crystal oscillator;
wherein the voltage is used by the PLL to temperature-compensate the phase locked clock waveform. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of temperature-stabilizing an oscillator comprising:
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receiving an input reference signal having a reference phase and frequency;
generating a voltage controlled oscillator (VCO) output signal based on the input reference signal;
feeding the VCO output signal through the feedback path to the phase detector;
receiving a temperature input in the feedback path; and
phase rotating the VCO output signal in the feedback path based on the temperature to perform fine frequency tuning the VCO output signal. - View Dependent Claims (8, 9, 10, 11)
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12. A environmental-compensated oscillator comprising:
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a reference clock waveform generator;
a phase locked loop (PLL) receiving the reference clock waveform and outputting a phase locked clock waveform;
a sensor outputting a voltage corresponding to an environmental parameter of the generator;
wherein the voltage is used by the PLL to compensate the phase locked clock waveform. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification