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US 6,473,485 B1Granted
Charge pump leakage current compensation systems and methods
AssigneeMicrel, Inc.
InventorFrancisco Fernandez-Texon
Life of this patent
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Abstract
A leakage current compensation system and method is disclosed that reduces frequency spurs and phase offset in a frequency synthesizer. The leakage current is determined based on the phase offset of the frequency synthesizer relative to a reference clock. A leakage current compensation circuit provides a leakage current compensation signal to the frequency synthesizer at the loop filter terminals to minimize the phase offset.
Claims10
A leakage current compensation circuit, comprising:
- a frequency synthesizer;
- a timing circuit coupled to the frequency synthesizer, the timing circuit receiving a clock signal from the frequency synthesizer and providing a timing signal indicating the timing of the clock signal relative to a reference clock signal;
- a counter coupled to the timing circuit, the counter providing a counter output value based on a value of the timing signal;
- and
- a digital-to-analog converter coupled to the counter and to the frequency synthesizer, the digital-to-analog converter receiving the counter output value and providing a leakage current compensation signal to the frequency synthesizer based on the counter output value.
2 more elements
A leakage current compensation circuit, comprising:
- a frequency synthesizer;
- means for monitoring the frequency synthesizer;
- and
- means for providing a leakage current compensation signal to the frequency synthesizer based on the monitoring to reduce the phase offset of the frequency synthesizer.
1 more element
A method of compensating for leakage current in a frequency synthesizer, the method comprising:
- monitoring a frequency synthesizer to determine when the frequency synthesizer is locked;
- determining a phase offset of the frequency synthesizer relative to a reference clock, when the frequency synthesizer is locked;
- and
- supplying a leakage current compensation signal to the frequency synthesizer based on the determining of the phase offset.
1 more element
Dependencies are inferred from the claim text.