Oscillators having reactance-adjustable frequency control
First Claim
1. An apparatus comprising:
- a reference oscillator configured to provide a first signal having a first frequency, the reference oscillator comprising at least one variable capacitor having a selected capacitance in response to a control signal;
a temperature sensor configured to generate a second signal in response to temperature;
a frequency controller coupled to the temperature sensor and to the reference oscillator, the frequency controller configured to provide the control signal in response to the second signal to maintain the first frequency within a predetermined frequency range over a predetermined temperature variation;
a frequency divider coupled to the reference oscillator and configured to provide an output reference signal having an output frequency determined from the first frequency and a divide value; and
at least one controlled reactance module electrically coupled to the reference oscillator, said at least one controlled reactance module responsive to a coefficient to switch a reactance of the controlled reactance module to the reference oscillator.
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Accused Products
Abstract
In various embodiments, the invention provides a frequency controller to control and provide a stable resonant frequency of a clock generator and/or a timing and frequency reference. Such stability is provided over variations in a selected parameter such as temperature and fabrication process variations. The various apparatus embodiments include a sensor adapted to provide a signal in response to at least one parameter of a plurality of parameters; and a frequency controller adapted to modify the resonant frequency in response to the second signal. In exemplary embodiments, the sensor is implemented as a current source responsive to temperature fluctuations, and the frequency controller is implemented as a plurality of controlled reactance modules which are selectively couplable to the resonator or to one or more control voltages. The controlled reactance modules may include fixed or variable capacitances or inductances, and may be binary weighted. Arrays of resistive modules are also provided, to generate one or more control voltages.
17 Citations
56 Claims
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1. An apparatus comprising:
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a reference oscillator configured to provide a first signal having a first frequency, the reference oscillator comprising at least one variable capacitor having a selected capacitance in response to a control signal; a temperature sensor configured to generate a second signal in response to temperature; a frequency controller coupled to the temperature sensor and to the reference oscillator, the frequency controller configured to provide the control signal in response to the second signal to maintain the first frequency within a predetermined frequency range over a predetermined temperature variation; a frequency divider coupled to the reference oscillator and configured to provide an output reference signal having an output frequency determined from the first frequency and a divide value; and at least one controlled reactance module electrically coupled to the reference oscillator, said at least one controlled reactance module responsive to a coefficient to switch a reactance of the controlled reactance module to the reference oscillator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. An apparatus comprising:
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a reference oscillator configured to provide a first signal having a first frequency, the reference oscillator comprising at least one variable capacitor having a capacitance set by a control signal; a temperature sensor configured to generate a second signal in response to measuring a temperature in the apparatus; a frequency controller coupled to the temperature sensor and to the reference oscillator, the frequency controller configured to generate the control signal in response to the second signal to maintain the first frequency within a first frequency range over a first variation in the temperature; and a plurality of switchable controlled reactance modules coupled to the reference oscillator, each switchable controlled reactance module responsive to a corresponding coefficient of a first plurality of coefficients to switch a corresponding reactance to the reference oscillator. - View Dependent Claims (25, 26, 27)
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28. An apparatus comprising:
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a reference oscillator configured to provide a first signal having a first frequency, the reference oscillator comprising at least one variable capacitor having a capacitance set by a control signal; a temperature sensor configured to generate a second signal in response to measuring a temperature in the apparatus; and a frequency controller coupled to the temperature sensor and to the reference oscillator, the frequency controller configured to generate the control signal in response to the second signal to maintain the first frequency within a first frequency range over a first variation in the temperature; wherein the reference oscillator further comprises an inductor and at least one switchable capacitor having a fixed capacitance.
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29. An apparatus comprising:
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a reference oscillator configured to provide a first signal having a first frequency, the reference oscillator comprising at least one variable capacitor having a capacitance set by a control signal; a temperature sensor configured to generate a second signal in response to measuring a temperature in the apparatus; and a frequency controller coupled to the temperature sensor and to the reference oscillator, the frequency controller configured to generate the control signal in response to the second signal to maintain the first frequency within a first frequency range over a first variation in the temperature; wherein the at least one variable capacitor is coupled through a switch to the frequency controller to receive the control signal.
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30. An apparatus comprising:
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a reference oscillator configured to provide a first signal having a first frequency, the reference oscillator comprising at least one variable capacitor having a capacitance set by a control signal; a temperature sensor configured to generate a second signal in response to measuring a temperature in the apparatus; and a frequency controller coupled to the temperature sensor and to the reference oscillator, the frequency controller configured to generate the control signal in response to the second signal to maintain the first frequency within a first frequency range over a first variation in the temperature; wherein the temperature sensor comprises; at least one resistive element; and a current source coupled to the at least one resistive element, the current source configured to provide a temperature-dependent current to generate the second signal as a temperature-dependent voltage across the at least one resistive element. - View Dependent Claims (31)
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32. An apparatus comprising:
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a reference resonator configured to provide a first signal having a resonant frequency, the reference resonator comprising a plurality of capacitors, a first capacitor of the plurality of capacitors having a fixed capacitance and a second capacitor of the plurality of capacitors having a variable capacitance controlled by a control voltage; a sensor configured to provide a second signal in response to a parameter of a plurality of parameters; and a frequency controller coupled to the sensor and to the reference resonator, the frequency controller configured to modify a capacitance of the reference resonator in response to the second signal to maintain the resonant frequency within a predetermined frequency range over a predetermined variance of the parameter; wherein the frequency controller is further configured to switch at least one of the first capacitor and the second capacitor to a ground potential or to a power supply or power rail voltage in response to a corresponding coefficient of a first plurality of coefficients to modify the capacitance of the reference resonator. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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47. An apparatus comprising:
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a reference resonator configured to provide a first signal having a resonant frequency, the reference resonator comprising a plurality of capacitors, a first capacitor of the plurality of capacitors having a fixed capacitance and a second capacitor of the plurality of capacitors having a variable capacitance controlled by a control voltage; a sensor configured to provide a second signal in response to a parameter of a plurality of parameters; and a frequency controller coupled to the sensor and to the resonator, the frequency controller configured to modify a capacitance of the reference resonator in response to the second signal to maintain the resonant frequency within a predetermined frequency range over a predetermined variance of the parameter; wherein the frequency controller is further configured to switch the second capacitor to the control voltage in response to a corresponding coefficient of the first plurality of coefficients to modify the capacitance of the reference resonator.
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48. An apparatus comprising:
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a reference resonator configured to provide a first signal having a resonant frequency, the reference resonator comprising a plurality of capacitors, a first capacitor of the plurality of capacitors having a fixed capacitance and a second capacitor of the plurality of capacitors having a variable capacitance controlled by a control voltage; a sensor configured to provide a second signal in response to a parameter of a plurality of parameters; and a frequency controller coupled to the sensor and to the resonator, the frequency controller configured to modify a capacitance of the reference resonator in response to the second signal to maintain the resonant frequency within a predetermined frequency range over a predetermined variance of the parameter; wherein the plurality of capacitors further comprises; a plurality of binary-weighted, switchable capacitive modules coupled to the resonator, 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 coefficients to switch between the fixed capacitance and the variable capacitance and to switch each variable capacitance to the control voltage.
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49. An apparatus comprising:
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a reference resonator configured to provide a first signal having a resonant frequency, the reference resonator comprising a plurality of capacitors, a first capacitor of the plurality of capacitors having a fixed capacitance and a second capacitor of the plurality of capacitors having a variable capacitance controlled by a control voltage; a sensor configured to provide a second signal in response to a parameter of a plurality of parameters; and a frequency controller coupled to the sensor and to the reference resonator, the frequency controller configured to modify a capacitance of the reference resonator in response to the second signal to maintain the resonant frequency within a predetermined frequency range over a predetermined variance of the parameter; wherein the sensor further comprises a current source responsive to temperature, and wherein the current source has a complementary to absolute temperature (CTAT) configuration, or a proportional to absolute temperature (PTAT) configuration, or a proportional to absolute temperature squared (PTAT2) configuration, or a combination of CTAT, PTAT and PTAT2 configurations.
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50. An apparatus for frequency control of a reference oscillator, the reference oscillator having an open-loop configuration for providing a first signal having a first frequency, the apparatus comprising:
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a coefficient register configured to store a first plurality of coefficients; and a plurality of switchable reactance modules coupled to the coefficient register and to the reference oscillator, each switchable reactance module responsive to a corresponding coefficient of the first plurality of coefficients to switch a corresponding reactance to a corresponding voltage to modify the resonant frequency; wherein said corresponding voltage is a control voltage, or is a power supply voltage, or is a power rail voltage or is a ground potential; and wherein the control voltage is determined by a current source responsive to temperature. - View Dependent Claims (51, 52, 53, 54, 55, 56)
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Specification