| US 7,612,617 B2 | ||
| Voltage-controlled oscillator gain calibration for two-point modulation in a phase-locked loop | ||
| Rajasekhar Pullela, Colton, Calif. (US); Morten Damgaard, Laguna Hills, Calif. (US); Shahrzad Tadjpour, Irvine, Calif. (US); John E. Vasa, Irvine, Calif. (US); and Hoon Lee, Irvine, Calif. (US) | ||
| Assigned to Skyworks Solutions, Inc., Woburn, Mass. (US) | ||
| Filed on Mar. 01, 2008, as Appl. No. 12/40,875. | ||
| Prior Publication US 2009/0219100 A1, Sep. 03, 2009 | ||
| Int. Cl. H03L 7/099 (2006.01); H03L 7/18 (2006.01) | ||
| U.S. Cl. 331—16 [331/17; 331/25; 331/44; 375/376] | 20 Claims |
| 1. A method for measuring gain of a voltage-controlled oscillator (VCO), comprising:
applying a first control signal to a phase-locked loop (PLL);
allowing the PLL to settle;
recording a first voltage at the input to the VCO in the PLL;
applying a second control signal different from the first control signal to the PLL;
adjusting the feedback path to compensate for an expected change in the voltage at the input to the VCO;
recording a second voltage at the input to the VCO;
determining if time is available to compare the measured change in voltage with a threshold value, wherein when time is unavailable
proceeding to calculate the gain of the VCO and terminating the method, otherwise when time is available;
determining whether a difference between the second voltage and the first voltage at the input to the VCO is within a specified
tolerance;
when the difference between the second voltage and the first voltage is not within a specified tolerance, further adjusting
the feedback path in response to the difference;
repeating the recording, determining and further adjusting steps until the difference between the second voltage and the first
voltage at the input to the VCO is within the specified tolerance; and
calculating the gain of the VCO.
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