US 12,463,588 B2
Phase noise reduction for voltage-controlled oscillator using harmonic filter
Sajin Mohamad, San Diego, CA (US); Burcin Serter Ergun, Poway, CA (US); Chiu Keung Tang, San Diego, CA (US); and Zhiqin Chen, San Diego, CA (US)
Assigned to QUALCOMM INCORPORATED, San Diego, CA (US)
Filed by QUALCOMM Incorporated, San Diego, CA (US)
Filed on Apr. 29, 2024, as Appl. No. 18/648,871.
Prior Publication US 2025/0337357 A1, Oct. 30, 2025
Int. Cl. H03B 1/04 (2006.01); H03B 5/12 (2006.01)
CPC H03B 1/04 (2013.01) [H03B 5/1228 (2013.01); H03B 5/1265 (2013.01); H03B 2201/0208 (2013.01)] 18 Claims
OG exemplary drawing
 
1. 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.