Phase noise reduction for voltage-controlled oscillator using harmonic filter
AssigneeQUALCOMM Incorporated
InventorsSajin Mohamad, Burcin Serter Ergun, Chiu Keung Tang, Zhiqin Chen
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Abstract
A system includes a voltage-controlled oscillator (VCO), a first second-order harmonic filter coupled to the VCO, wherein the first second-order harmonic filter includes a first tunable capacitor, and a second second-order harmonic filter coupled to the VCO, wherein the second second-order harmonic filter includes a second tunable capacitor. The system also includes a measurement circuit coupled to the VCO, wherein the measurement circuit is configured to measure a voltage swing of the VCO. The system also includes a control circuit coupled to the measurement circuit, the first tunable capacitor, and the second tunable capacitor.
Claims18
A system, comprising:
- a voltage-controlled oscillator (VCO);
- a first second-order harmonic filter coupled to the VCO, wherein the first second-order harmonic filter includes a first tunable capacitor;
- a second second-order harmonic filter coupled to the VCO, wherein the second second-order harmonic filter includes a second tunable capacitor;
- a measurement circuit coupled to the VCO, wherein the measurement circuit is configured to measure a voltage swing of the VCO;
- and
- a control circuit coupled to the measurement circuit, the first tunable capacitor, and the second tunable capacitor, wherein:
- the control circuit is configured to sequentially set the first tunable capacitor and the second tunable capacitor to each one of multiple capacitance settings;
- and
- the measurement circuit is configured to measure the voltage swing for each one of the multiple capacitance settings.
A system, comprising:
- a voltage-controlled oscillator (VCO), wherein the VCO includes an inductor and a voltage-controlled capacitor coupled in parallel between a first node and a second node;
- a first second-order harmonic filter coupled to the VCO, wherein the first second-order harmonic filter includes a first tunable capacitor;
- a second second-order harmonic filter coupled to the VCO, wherein the second second-order harmonic filter includes a second tunable capacitor;
- a measurement circuit having a first input and a second input, wherein the first input of the measurement circuit is coupled to the first node, the second input of the measurement circuit is coupled to the second node, and the measurement circuit is configured to measure a voltage difference between the first node and the second node;
- and
- a control circuit coupled to the measurement circuit, the first tunable capacitor, and the second tunable capacitor, wherein:
- the control circuit is configured to sequentially set the first tunable capacitor and the second tunable capacitor to each one of multiple capacitance settings;
- and
- the measurement circuit is configured to measure the voltage difference between the first node and the second node for each one of the multiple capacitance settings.
A method for calibrating a first second-order harmonic filter and a second second-order harmonic filter coupled to a voltage-controlled oscillator (VCO), wherein the first second-order harmonic filter includes a first tunable capacitor and the second second-order harmonic filter includes a second tunable capacitor, the method comprising:
- sequentially setting the first tunable capacitor and the second tunable capacitor to each one of multiple capacitance settings;
- measuring a voltage swing of the VCO for each one of the multiple capacitance settings;
- and
- selecting one of the multiple capacitance settings based on the measured voltage swings for the multiple capacitance settings.
Dependencies are inferred from the claim text.