Systems and methods for providing an adjustable reference signal to RF circuitry

  • US 7,035,607 B2
  • Filed: 07/31/2003
  • Issued: 04/25/2006
  • Est. Priority Date: 05/29/1998
  • Status: Expired due to Term
First Claim
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1. A circuit for providing an adjustable reference signal to radio frequency (RF) circuitry, said circuit comprising:

  • frequency modification circuitry comprising at least one variable capacitance device, said frequency modification circuit being configured for coupling to a crystal to form a crystal oscillator circuit that is capable of providing said adjustable reference signal to at least one component of said RF circuitry;

    wherein said at least one variable capacitance device is configured to adjust the frequency of said adjustable reference signal;

    wherein said at least one variable capacitance device is configured to adjust the frequency of said adjustable reference signal based at least in part on at least one frequency control signal received by said frequency modification circuitry; and

    wherein said variable capacitance device comprises;

    variable capacitor circuitry configured to adjust the frequency of said adjustable reference signal in response to a plurality of control voltage signals, andcontrol circuitry, the control circuitry configured to generate the plurality of control voltage signals in response to said at least one frequency control signal received by said frequency modification circuitry,wherein the voltage level of each of the plurality of the control voltage signals differs by an offset voltage from the voltage level of the remaining signals in the plurality of control voltage signals.

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