Method and apparatus for providing coarse and fine tuning control for synthesizing high-frequency signals for wireless communications
DCFirst Claim
1. A method for operating a wireless communication system, comprising:
- receiving an input signal;
generating a mixing signal having a frequency dependent upon a capacitance provided by a first and a second capacitance circuits within a single integrated circuit;
tuning the mixing signal frequency for the mixing signal to within a selected amount of a desired mixing signal frequency by adjusting a capacitance amount for the first capacitance circuit;
further tuning the mixing signal frequency to the desired mixing signal frequency for the mixing signal by adjusting the capacitance amount for the second capacitance circuit; and
combining the mixing signal with the input signal to produce an output signal at a desired frequency,wherein the further tuning step comprises adjusting a control signal to adjust the capacitance amount for the second capacitance circuit;
wherein the capacitance amount for the second capacitance circuit comprises a plurality of continuous capacitance values, and wherein the 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.
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Abstract
A method and apparatus for synthesizing high-frequency signals is disclosed that overcomes integration problem associated with prior implementations while meeting demanding phase noise and other impurity requirements. In one embodiment, a phase-locked loop (PLL) frequency synthesizer is disclosed having a voltage controlled oscillator (VCO) with a variable capacitance that includes a discretely variable capacitance in conjunction with a continuously variable capacitance. The discretely variable capacitance may provide coarse tuning adjustment of the variable capacitance, and the continuously variable capacitance may provide a fine tuning adjustment of the variable capacitance. In a more general terms, a frequency synthesizer is disclosed having a first variable and a second capacitance circuits and frequency control circuitry to coarsely tune the output frequency by adjusting the first control signal and to finely tune the output frequency by adjusting the second control signal.
194 Citations
29 Claims
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1. A method for operating a wireless communication system, comprising:
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receiving an input signal; generating a mixing signal having a frequency dependent upon a capacitance provided by a first and a second capacitance circuits within a single integrated circuit; tuning the mixing signal frequency for the mixing signal to within a selected amount of a desired mixing signal frequency by adjusting a capacitance amount for the first capacitance circuit; further tuning the mixing signal frequency to the desired mixing signal frequency for the mixing signal by adjusting the capacitance amount for the second capacitance circuit; and combining the mixing signal with the input signal to produce an output signal at a desired frequency, wherein the further tuning step comprises adjusting a control signal to adjust the capacitance amount for the second capacitance circuit; wherein the capacitance amount for the second capacitance circuit comprises a plurality of continuous capacitance values, and wherein the 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A wireless communication system, comprising:
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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. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification