Counter-based resonator frequency compensation
View Patent ↗Disclosed herein is a timing device that includes a resonator device to generate a resonator output signal at a frequency offset from a desired frequency, a counter configured to generate an extraction signal in accordance with the frequency offset, and a timing signal generator configured to track time with a count based on the resonator output signal and modified by the extraction signal downward to reach the desired frequency.
1. A timing device, comprising:
a resonator device to generate a resonator output signal at a frequency above a desired frequency;
a calculator to determine a corrected frequency offset to compensate for an initial frequency offset of the resonator device and to adjust for frequency variation during operation of the resonator device;
a counter configured to generate an extraction signal in accordance with the corrected frequency offset; and
a timing signal generator configured to track time with a count based on the resonator output signal and modified by the extraction signal downward to reach the desired frequency.
2. The timing device of claim 1 , wherein the counter comprises an integer counter configured to generate a pulse at regular intervals at a frequency in accordance with the corrected frequency offset.
3. The timing device of claim 1 , wherein the counter comprises a fractional counter configured to track a fractional remainder between a number of pulses used to generate a pulse of the extraction signal and the corrected frequency offset.
4. The timing device of claim 1 , further comprising a memory configured to store the initial frequency offset of the resonator device.
5. The timing device of claim 1 , further comprising a temperature sensor configured to measure an operating temperature of the resonator device and coupled to the calculator such that the corrected frequency offset is based on the measured operating temperature.
6. The timing device of claim 1 , further comprising a memory configured to store an aging rate for the resonator device and coupled to the calculator such that the corrected frequency offset is based on the aging rate.
7. A method of generating a timing signal of a desired frequency, the method comprising the steps of:
generating a resonator output signal from a resonator device at a frequency above the desired frequency;
determining a corrected frequency offset to compensate for an initial frequency offset of the resonator device and to adjust for frequency variation during operation of the resonator device;
generating an extraction signal in accordance with the corrected frequency offset;
generating the timing signal with a count based on the output signal and modified by the extraction signal downward to reach the desired frequency.
8. The method of claim 7 , wherein the extraction signal generating step comprises utilizing a counter to generate a pulse at regular intervals at a frequency in accordance with the corrected frequency offset.
9. The method of claim 7 , wherein the extraction signal generating step comprises tracking a fractional remainder between a number of pulses used to generate a pulse of the extraction signal and the corrected frequency offset.
10. The method of claim 7 , further comprising the steps of measuring an operating temperature of the resonator device, and determining a representation of the frequency variation from the measured operating temperature such that the corrected frequency offset is based on the measured operating temperature.
11. The method of claim 7 , further comprising the step of determining a representation of the frequency variation based on an aging rate for the resonator output signal.