Frequency calibration for a monolithic clock generator and timing/frequency reference

A frequency calibration system, the system couplable to an oscillator to receive a reference signal having a reference frequency, the system comprising:

• a reference oscillator comprising at least one reactance and a coefficient register, the reference oscillator to provide an oscillation signal having an oscillation frequency;
• a frequency divider couplable to the reference oscillator, the frequency divider to provide an output signal having an output frequency;
• a comparator coupled to the frequency divider, the comparator to compare the output frequency to the reference frequency using a first predetermined level of discrimination, to provide a first comparison signal when the output frequency is higher than the reference frequency, and to provide a second comparison signal when the output frequency is lower than the reference frequency;
• and
• a reactance modulator coupled to the comparator and couplable to the reference oscillator, the reactance modulator to determine and provide to the coefficient register a plurality of coefficients to increase a reactance of the reference oscillator in response to the first comparison signal or to decrease the reactance of the reference oscillator in response to the second comparison signal.

An apparatus for frequency calibration of a free-running, reference harmonic oscillator, the oscillator to provide an oscillation signal having an oscillation frequency, the oscillator comprising at least one reactance and a coefficient register, the apparatus couplable to receive a reference signal having a reference frequency, the apparatus comprising:

• a frequency divider couplable to the oscillator, the frequency divider to provide an output signal having an output frequency;
• a comparator coupled to the frequency divider, the comparator to compare the output frequency to the reference frequency using a first predetermined level of discrimination, to provide first comparison signal when the output frequency is higher than the reference frequency, and to provide a second comparison signal when the output frequency is lower than the reference frequency;
• and
• a reactance modulator coupled to the comparator and couplable to the oscillator, the reactance modulator to determine and provide to the coefficient register a plurality of coefficients to increase a reactance of the oscillator in response to the first comparison signal or to decrease the reactance of the oscillator in response to the second comparison signal.

A frequency calibration system, the system couplable to a first reference oscillator to receive a reference signal having a reference frequency, the system comprising:

• an independent, calibrated reference harmonic oscillator, the harmonic oscillator comprising a plurality of reactances and a coefficient register, the harmonic oscillator to provide an oscillation signal having an oscillation frequency;
• a frequency divider coupled to the harmonic oscillator, the frequency divider to provide an output signal having an output frequency which is a rational multiple or fraction of the oscillation frequency;
• a comparator coupled to the frequency divider, the comparator to compare the output frequency to the reference frequency using a first predetermined level of discrimination, to compare the output frequency to the reference frequency using a second predetermined level of discrimination, and to provide a first comparison signal when the output frequency is higher than the reference frequency or provide a second comparison signal when the output frequency is lower than the reference frequency, the comparator further adared to determine a remainder as a cycle count difference between the reference frequency and the output frequency, to determine a lowest remainder, and to store a corresponding plurality of coefficients which produced the output frequency having the lowest remainder;
• and
• a reactance modulator coupled to the comparator and to the oscillator, the reactance modulator to determine and provide to the coefficient register a plurality of coefficients to increase a reactance of the oscillator in response to the first comparison signal or to decrease the reactance of the oscillator in response to the second comparison signal, the reactance modulator further to select the plurality of coefficients which produced the output frequency having the lowest remainder and provide the plurality of coefficients as the frequency calibration of the harmonic oscillator.