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Clock, frequency reference, and other reference signal generator with frequency stability over temperature variation

  • US 8,134,414 B2
  • Filed: 04/23/2010
  • Issued: 03/13/2012
  • Est. Priority Date: 04/24/2009
  • Status: Active Grant
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, the reference resonator comprising a first component having a first temperature dependence; and

    a plurality of switchable circuits couplable to the reference resonator, at least one switchable circuit of the plurality of switchable circuits having a second temperature dependence opposing the first temperature dependence to maintain the resonant frequency within a predetermined variance over a temperature variation;

    wherein each switchable circuit of the plurality of switchable circuits comprises;

    a first reactance coupled in series with a first switch;

    a resistor;

    a second reactance coupled to the resistor; and

    a second switch coupled in series to the second reactance or to the resistor;

    wherein the first switch is responsive to a control signal of a plurality of control signals to electronically couple or decouple the first reactance to or from a voltage, a ground potential, or the reference resonator; and

    wherein the second switch is responsive to an inverted control signal of a plurality of control signals to electronically couple or decouple the second reactance or the resistor to or from a voltage, a ground potential, or the reference resonator.

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