Patent ID: 7221921

Claim:
A radio-frequency (RF) apparatus comprising: one or more integrated circuits comprising integrated RF circuitry, said integrated RF circuitry including integrated digital-to-analog conversion (DAC) circuitry; and external frequency modification circuitry coupled to said integrated RF circuitry and comprising at least one variable capacitance device, said external frequency modification circuit being configured for coupling to a crystal to form a crystal oscillator circuit that is capable of generating an adjustable reference signal and of providing said adjustable reference signal to said integrated RF circuitry, said at least one variable capacitance device configured to adjust the frequency of said adjustable reference signal based at least in part on one or more analog frequency control signals received by said external frequency modification circuitry; wherein said integrated RF circuitry is configured for coupling to baseband processor circuitry, and wherein said integrated DAC circuitry is configured to receive one or more digital frequency control signals from said baseband processor circuitry and to generate and provide at least a portion of said one or more analog frequency control signals to said external frequency modification circuit based on said one or more digital frequency control signals.