Control voltage generator for a clock, frequency reference, and other reference signal generator
First Claim
1. An apparatus to generate a harmonic reference signal, the apparatus comprising:
- a reference resonator configured to generate a first reference signal having a resonant frequency;
a control voltage generator configured to provide a temperature-dependent control voltage, said control voltage generator comprising;
a first current source configured to generate a temperature-dependent current;
a variable resistance circuit coupled to the first current source, an amount of resistance of the variable resistance circuit selectable to determine a variation in the temperature-dependent current for a corresponding variation in temperature; and
a plurality of variable reactance modules couplable to the reference resonator and couplable to the control voltage generator, each reactance module of the plurality of variable reactance modules configured to modify a corresponding reactance in response to the control voltage to maintain the resonant frequency within a predetermined variance over a predetermined temperature range;
wherein the variable resistance circuit comprises;
a plurality of resistors, each resistor of the plurality of resistors having a fixed resistance;
a plurality of switches correspondingly coupled to the plurality of resistors, each switch of the plurality of switches responsive to a control coefficient to couple or uncouple a corresponding resistor of the plurality of resistors to provide the variable resistance; and
a plurality of current mirrors or current sources correspondingly couplable through the plurality of switches to the plurality of resistors.
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Accused Products
Abstract
Exemplary embodiments of the invention provide a reference signal generator, system and method. An exemplary apparatus to generate a harmonic reference signal includes a reference resonator, such as an LC-tank, a control voltage generator adapted to provide a temperature-dependent control voltage; and a plurality of variable reactance modules. The reference resonator generates a first reference signal having a resonant frequency, and each reactance module is adapted to modify a corresponding reactance in response to the control voltage to maintain the resonant frequency substantially constant or within a predetermined variance over a predetermined temperature range. A frequency controller may also be included to maintain substantially constant a magnitude of a peak amplitude of the first reference signal and maintains substantially constant a common mode voltage level of the reference resonator.
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Citations
20 Claims
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1. An apparatus to generate a harmonic reference signal, the apparatus comprising:
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a reference resonator configured to generate a first reference signal having a resonant frequency; a control voltage generator configured to provide a temperature-dependent control voltage, said control voltage generator comprising; a first current source configured to generate a temperature-dependent current; a variable resistance circuit coupled to the first current source, an amount of resistance of the variable resistance circuit selectable to determine a variation in the temperature-dependent current for a corresponding variation in temperature; and a plurality of variable reactance modules couplable to the reference resonator and couplable to the control voltage generator, each reactance module of the plurality of variable reactance modules configured to modify a corresponding reactance in response to the control voltage to maintain the resonant frequency within a predetermined variance over a predetermined temperature range; wherein the variable resistance circuit comprises; a plurality of resistors, each resistor of the plurality of resistors having a fixed resistance; a plurality of switches correspondingly coupled to the plurality of resistors, each switch of the plurality of switches responsive to a control coefficient to couple or uncouple a corresponding resistor of the plurality of resistors to provide the variable resistance; and a plurality of current mirrors or current sources correspondingly couplable through the plurality of switches to the plurality of resistors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus to generate a harmonic reference signal, the apparatus comprising:
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a reference resonator configured to generate a first reference signal having a resonant frequency; a control voltage generator configured to provide a temperature-dependent control voltage, said control voltage generator comprising; a first current source configured to generate a temperature-dependent current; and a variable resistance circuit coupled to the first current source, an amount of resistance of the variable resistance circuit selectable to determine a variation in the temperature-dependent current for a corresponding variation in temperature; and a plurality of variable reactance modules couplable to the reference resonator and couplable to the control voltage generator, each reactance module of the plurality of variable reactance modules configured to modify a corresponding reactance in response to the control voltage to maintain the resonant frequency within a predetermined variance over a predetermined temperature range; wherein the variable resistance circuit comprises; a second current source; and at least two resistors coupled to the second current source. - View Dependent Claims (12, 13)
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14. An apparatus to generate a harmonic reference signal, the apparatus comprising:
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a reference resonator configured to generate a first reference signal having a resonant frequency; a control voltage generator configured to provide a temperature-dependent control voltage, said control voltage generator comprising; a first current source configured to generate a temperature-dependent current; a variable resistance circuit coupled to the first current source, an amount of resistance of the variable resistance circuit selectable to determine a variation in the temperature-dependent current for a corresponding variation in temperature; a reference voltage generator to generate a reference voltage; a first operational amplifier coupled to the reference voltage generator, the first current source, and the variable resistance circuit; and at least one second current source coupled to the first operational amplifier to provide a DC offset for the control voltage; and a plurality of variable reactance modules couplable to the reference resonator and couplable to the control voltage generator, each reactance module of the plurality of variable reactance modules configured to modify a corresponding reactance in response to the control voltage to maintain the resonant frequency within a predetermined variance over a predetermined temperature range.
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15. An integrated circuit, comprising:
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a reference oscillator configured to generate a reference signal having a reference frequency; a controller coupled to the reference oscillator, the controller configured to maintain substantially constant a peak amplitude of the reference signal and a common mode voltage level of the reference oscillator; a control voltage generator configured to provide a control voltage which varies substantially linearly in response to temperature, the control voltage generator comprising a configurable resistance, a first current source and a second current source, the first and second current sources having opposing current responses to temperature variation and the configurable resistance comprising at least one third current source and at least two resistors coupled to the third current source; and a plurality of varactors configured to receive the control voltage and provide a corresponding capacitance to maintain the reference frequency within a predetermined variance of a predetermined frequency in response to temperature variation. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification