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Control voltage generator for a clock, frequency reference, and other reference signal generator

  • US 7,978,017 B2
  • Filed: 01/12/2008
  • Issued: 07/12/2011
  • Est. Priority Date: 12/05/2007
  • Status: Expired due to Fees
First Claim
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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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