Low power automatic calibration method for high frequency oscillators
First Claim
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1. A clock calibration method comprising the steps of:
- [0] developing a first control signal as a function of temperature;
[1] in response to the first control signal;
[1.1] in response to a second control signal, selectively enabling a reference clock oscillator to develop reference clock pulses at a selected reference frequency; and
[1.2] in response to a third control signal, selectively enabling a measured clock oscillator to develop measured clock pulses at a frequency determined as a function of an adjustment value;
[2] in response to a first one of the reference clock pulses, initiating counting of the measured clock pulses;
[3] in response to a second reference clock pulse, terminating counting of the measured clock pulses; and
[4] adjusting the adjustment value as a function of a difference between the count of the measured clock pulses and a selected target value.
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Abstract
A clock calibrator for use in an electronic system comprising an integrated circuit such as a microcontroller. The clock calibrator embodies a frequency adjustment facility adapted dynamically to adjust the frequency of one or more high-frequency clock generators as a function of a lower-frequency reference clock.
4 Citations
12 Claims
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1. A clock calibration method comprising the steps of:
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[0] developing a first control signal as a function of temperature; [1] in response to the first control signal; [1.1] in response to a second control signal, selectively enabling a reference clock oscillator to develop reference clock pulses at a selected reference frequency; and [1.2] in response to a third control signal, selectively enabling a measured clock oscillator to develop measured clock pulses at a frequency determined as a function of an adjustment value; [2] in response to a first one of the reference clock pulses, initiating counting of the measured clock pulses; [3] in response to a second reference clock pulse, terminating counting of the measured clock pulses; and [4] adjusting the adjustment value as a function of a difference between the count of the measured clock pulses and a selected target value. - View Dependent Claims (2, 3, 11, 12)
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4. A clock calibration method comprising the steps of:
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[0] developing a first control signal as a function of temperature; [1] in response to the first control signal; [1.1] in response to a second control signal, selectively enabling a reference clock oscillator to develop reference clock pulses at a selected reference frequency; and [1.2] in response to a third control signal, selectively enabling a measured clock oscillator to develop measured clock pulses at a frequency determined as a function of an adjustment value; and [2] in response to a selected one of the reference clock pulses, adjusting the adjustment value as a function of a difference between the frequency of the measured clock relative to the frequency of the reference clock. - View Dependent Claims (5, 6)
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7. A clock calibration method comprising the steps of:
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[0] developing a first control signal as a function of temperature; [1] in response to the first control signal, selectively enabling a reference clock oscillator to develop reference clock pulses at a selected reference frequency; [2] in response to a second control signal, selectively enabling a measured clock oscillator to develop measured clock pulses at a frequency determined as a function of an adjustment value; [3] in response to a first one of the reference clock pulses, initiating counting of the measured clock pulses; [4] in response to a second reference clock pulse, terminating counting of the measured clock pulses; [5] adjusting the adjustment value as a function of a difference between the count of the measured clock pulses and a selected target value; [6] selectively repeating steps [3] through [5]; [7] in response to the first control signal, selectively disabling the reference clock oscillator; and [8] in response to the second control signal, selectively disabling the measured clock oscillator. - View Dependent Claims (9, 10)
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8. A clock calibration method comprising the steps of:
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[0] developing a first control signal as a function of temperature; [1] in response to the first control signal, selectively enabling a reference clock oscillator to develop reference clock pulses at a selected reference frequency; [2] in response to a second control signal, selectively enabling a measured clock oscillator to develop measured clock pulses at a frequency determined as a function of an adjustment value; and [3] in response to a selected one of the reference clock pulses, adjusting the adjustment value as a function of a difference between the frequency of the measured clock relative to the frequency of the reference clock.
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Specification