Method and apparatus for providing coarse and fine tuning control for synthesizing high-frequency signals for wireless communications

A wireless communication system, comprising:

• a frequency synthesizer having a mixing signal as an output with a frequency that is dependent upon a first variable capacitance circuit having a first control signal and a second variable capacitance circuit having a second control signal, the frequency synthesizer including frequency control circuitry to provide the first control signal to coarsely tune the frequency of the mixing signal and to provide the second control signal to finely tune the frequency of the mixing signal and the frequency synthesizer being integrated on a single integrated circuit;
• and
• mixing circuitry coupled to receive an input signal and to receive the mixing signal from the frequency synthesizer, the mixing circuitry having an output signal with a frequency dependent upon the frequency of the mixing signal;
• wherein the first control signal adjusts the capacitance amount for the first variable capacitance circuit;
• wherein the second control signal adjusts the capacitance amount for the second variable capacitance circuit;
• wherein the capacitance amount for the second variable capacitance circuit comprises a plurality of continuous capacitance values;
• wherein the second control signal comprises a plurality of variable control signals and wherein a relatively linear circuit behavior for the second capacitance circuit is achieved over a selected frequency range.