Monolithic clock generator and timing/frequency reference

An apparatus, comprising:

• a reference resonator adapted to provide a first reference signal having a resonant frequency;
• a frequency controller coupled to the reference resonator, the frequency controller adapted to be calibrated to determine the resonant frequency having a first frequency of a plurality of frequencies;
• and
• an amplifier coupled to the reference resonator, said amplifier comprising a negative transconductance amplifier;
• wherein the frequency controller is further adapted to modify a current through the negative transconductance amplifier in response to temperature;
• wherein the frequency controller further comprises a current source responsive to temperature;
• and
• wherein the current source further comprises one or more CTAT, PTAT, or PTAT2 configurations.

An apparatus, comprising:

• a reference resonator adapted to provide a first reference signal having a resonant frequency;
• a frequency controller coupled to the reference resonator, the frequency controller adapted to be calibrated to determine the resonant frequency having a first frequency of a plurality of frequencies;
• and
• an amplifier coupled to the reference resonator, said amplifier comprising a negative transconductance amplifier;
• wherein the frequency controller is further adapted to modify a current through the negative transconductance amplifier in response to temperature;
• and
• wherein the frequency controller is further adapted to modify a transconductance of the negative transconductance amplifier to modify the resonant frequency of the reference resonator.

An apparatus, comprising:

• a reference resonator adapted to provide a first reference signal having a resonant frequency;
• and
• a frequency controller coupled to the reference resonator, the frequency controller adapted to be calibrated to determine the resonant frequency having a first frequency of a plurality of frequencies, said frequency controller further comprising:
• a first array having a plurality of switchable capacitive modules coupled to the reference resonator, each switchable capacitive module having a fixed capacitance and a variable capacitance, each switchable capacitive module responsive to a corresponding coefficient of a first plurality of calibration coefficients to switch between the fixed capacitance and the variable capacitance and to switch each variable capacitance to a control voltage.

An apparatus, comprising:

• a reference resonator adapted to provide a first reference signal having a resonant frequency;
• and
• a frequency controller coupled to the reference resonator, the frequency controller adapted to be calibrated to determine the resonant frequency having a first frequency of a plurality of frequencies;
• wherein the frequency controller further comprises:
• an array having a plurality of switchable variable capacitive modules coupled to the reference resonator, each switchable variable capacitive module responsive to a corresponding coefficient of a first plurality of calibration coefficients to switch between a first voltage and a second voltage.

An apparatus, comprising:

• a reference resonator adapted to provide a first reference signal having a resonant frequency;
• and
• a frequency controller coupled to the reference resonator, the frequency controller adapted to be calibrated to determine the resonant frequency having a first frequency of a plurality of frequencies;
• wherein the frequency controller further comprises:
• an array having a plurality of switchable capacitive modules coupled to the reference resonator, each switchable capacitive module having a fixed capacitance and a fuse, each switchable capacitive module responsive to a corresponding coefficient of a first plurality of calibration coefficients to open circuit the fuse.

An apparatus, comprising:

• a reference resonator adapted to provide a first reference signal having a resonant frequency;
• a frequency controller coupled to the reference resonator, the frequency controller adapted to be calibrated to determine the resonant frequency having a first frequency of a plurality of frequencies;
• and
• a frequency calibration module coupled to the frequency controller, the frequency calibration module adapted to determine the calibration of the frequency controller in response to a second reference signal;
• wherein the frequency calibration module comprises:
• a frequency divider coupled to the frequency controller, the frequency divider adapted to convert an output signal derived from the first reference signal having the first frequency to a lower frequency to provide a divided signal;
• a frequency detector coupled to the frequency divider, the frequency detector adapted to compare the second reference signal to the divided signal and provide one or more up signals or down signals;
• and
• a pulse counter coupled to the frequency detector, the pulse counter adapted to determine a difference between the one or more up signals or down signals as an indicator of a difference between the output signal and the second reference signal.

An apparatus, comprising:

• a reference resonator adapted to provide a first reference signal having a resonant frequency;
• a frequency controller coupled to the reference resonator, the frequency controller adapted to be calibrated to determine the resonant frequency having a first frequency of a plurality of frequencies;
• a second oscillator providing a second oscillator output signal;
• and
• a mode selector coupled to the frequency controller and to the second oscillator, the mode selector adapted to switch to the second oscillator output signal to provide a power conservation mode.

An apparatus, comprising:

• a reference resonator adapted to provide a first reference signal having a resonant frequency;
• and
• a frequency controller coupled to the reference resonator, the frequency controller adapted, when calibrated, to select the resonant frequency having a first frequency of a plurality of frequencies;
• wherein the frequency controller further comprises:
• a first array having a plurality of switchable capacitive modules coupled to the reference resonator, each switchable capacitive module having a fixed capacitance and a variable capacitance, each switchable capacitive module responsive to a corresponding coefficient of a first plurality of calibration coefficients to switch between the fixed capacitance and the variable capacitance and to switch each variable capacitance to a control voltage.

An apparatus, comprising:

• a reference resonator adapted to provide a first reference signal having a resonant frequency;
• and
• a frequency controller coupled to the reference resonator, the frequency controller adapted, when calibrated, to select the resonant frequency having a first frequency of a plurality of frequencies;
• and
• a negative transconductance amplifier coupled to the reference resonator;
• wherein the frequency controller is further adapted to modify a current through the negative transconductance amplifier in response to temperature;
• wherein the frequency controller further comprises a current source responsive to temperature;
• and
• wherein the current source further comprises one or more CTAT, PTAT, or PTAT2 configurations.

An apparatus, comprising:

• a reference oscillator adapted to provide a first reference signal having an oscillation frequency;
• an amplifier coupled to the reference oscillator;
• a process variation compensator coupled to the reference oscillator, the process variation compensator adapted to determine the oscillation frequency when calibrated for fabrication process variation;
• and
• a temperature compensator coupled to the amplifier or the reference oscillator, the temperature compensator adapted to maintain substantially the determined oscillation frequency of the reference oscillator in response to a temperature variation;
• wherein the temperature compensator further comprises:
• a coefficient register adapted to store a first plurality of coefficients and a second plurality of coefficients;
• a first array having a plurality of binary-weighted switchable capacitance branches coupled to the coefficient register and to the reference oscillator, each switchable capacitance branch having a fixed capacitance and a variable capacitance and responsive to a corresponding coefficient of the first plurality of coefficients to switch between the fixed capacitance and the variable capacitance and to switch the variable capacitance to a control voltage node;
• a second array coupled to the control voltage node, the second array having a plurality of switchable resistances coupled to the coefficient register and further having a fixed capacitance, each switchable resistive module responsive to a corresponding coefficient of the second plurality of coefficients to switch the switchable resistive module to the control voltage node;
• and
• a temperature-dependent current source coupled through a current mirror to the second array.

An apparatus, comprising:

• a reference oscillator adapted to provide a first reference signal having an oscillation frequency;
• an amplifier coupled to the reference oscillator;
• a process variation compensator coupled to the reference oscillator, the process variation compensator adapted to determine the oscillation frequency when calibrated for fabrication process variation;
• and
• a temperature compensator coupled to the amplifier or the reference oscillator, the temperature compensator adapted to maintain substantially the determined oscillation frequency of the reference oscillator in response to a temperature variation;
• wherein the process variation compensator further comprises:
• a coefficient register embodied as one or more memory circuits and adapted to store a first plurality of calibration coefficients;
• and
• wherein the process variation compensator further comprises:
• a first array having a plurality of switchable capacitive modules coupled to the coefficient register and to the reference oscillator, each switchable capacitive module having a fixed capacitance and a variable capacitance, each switchable capacitive module responsive to a corresponding coefficient of the first plurality of calibration coefficients to switch between the fixed capacitance and the variable capacitance and to switch each variable capacitance to a control voltage.

An apparatus, comprising:

• a reference oscillator adapted to provide a first reference signal having an oscillation frequency;
• an amplifier coupled to the reference oscillator;
• a process variation compensator coupled to the reference oscillator, the process variation compensator adapted to determine the oscillation frequency when calibrated for fabrication process variation;
• and
• a temperature compensator coupled to the amplifier or the reference oscillator, the temperature compensator adapted to maintain substantially the determined oscillation frequency of the reference oscillator in response to a temperature variation;
• wherein the process variation compensator further comprises:
• a coefficient register embodied as one or more memory circuits and adapted to store a first plurality of calibration coefficients;
• and
• wherein the process variation compensator further comprises:
• a first array having a plurality of switchable resistive modules coupled to the coefficient register and further having a capacitive module, the capacitive module and the plurality of switchable resistive Modules further coupled to a node to provide the control voltage, each switchable resistive module responsive to a corresponding coefficient of a second plurality of coefficients stored in the coefficient register to switch the switchable resistive module to the control voltage node;
• and
• a temperature-dependent current source coupled through a current mirror to the second array.