| US 7,352,249 B2 | ||
| Phase-locked loop bandwidth calibration circuit and method thereof | ||
| Edmund J. Balboni, Littleton, Mass. (US); Wyn T. Palmer, Reading, Mass. (US); and Jonathan R. Strange, Reigate (United Kingdom) | ||
| Assigned to Analog Devices, Inc., Norwood, Mass. (US) | ||
| Filed on Oct. 03, 2003, as Appl. No. 10/679,023. | ||
| Prior Publication US 2005/0073369 A1, Apr. 07, 2005 | ||
| Int. Cl. H03L 7/085 (2006.01) | ||
| U.S. Cl. 331—16 [331/17; 327/157] | 15 Claims |
| 1. A phase-locked loop bandwidth calibration circuit, comprising:
a programmable charge pump;
a phase-locked loop filter operatively connected to said programmable charge pump;
an oscillator, operatively connected to said phase-locked loop filter, to generate a frequency signal based upon a signal
received from said phase-locked loop filter; and
a control loop operatively connected to said phase-locked loop filter and said programmable charge pump;
said control loop including a gain measurement circuit, operatively connected to said oscillator, to measure a gain of said
oscillator;
said control loop controlling said programmable charge pump to adjust its output current level based on the measured gain
of said oscillator;
said gain measurement circuit including,
a voltage difference measurement circuit, operatively connected to said phase-locked loop filter, to measure a voltage difference
corresponding to two voltages being output from said phase-locked loop filter at different times,
an analog to digital converter, operatively connected to said voltage difference measurement circuit, to convert the measured
voltage difference into a digital signal, and
a controller to cause said programmable charge pump to adjust its output current level based upon a received digital signal
from said analog to digital converter.
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