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US 6,486,650 B1Granted
Frequency locked loop speed up
Assignee3Com Corporation
InventorsBrewster T. Hudson, Anthony Eugene Zortea
Life of this patent
Estimating the term…
Abstract
In at least one implementation, a method is provided for testing a communication circuit having a clock recovery circuit. The method comprising initializing a voltage controlled oscillator to near an expected operating frequency upon power up of the clock recovery circuit by supplying a signal from an external tester.
Claims14
A method for testing a communication circuit having a clock recovery circuit, the method comprising:
- a) applying power to the clock recovery circuit;
- and
- b) initializing a voltage controlled oscillator to near an expected operating frequency upon power up of the clock recovery circuit by:
- supplying a precharge signal from an external tester to a charge pump, the precharge signal being selectively supplied to the charge pump via a selector, the selector also selectively supplying a frequency error signal from frequency lock circuitry and a phase correction signal from phase lock circuitry to the charge pump,
- the charge pump being connected to the voltage controlled oscillator to supply a drive signal to drive the voltage controlled oscillator based on the supplied signal from the selector;
- wherein the precharge signal supplies a predetermined number of up pulses to the charge pump to more quickly drive the voltage controlled oscillator to near the expected operating frequency.
3 more elements
Dependencies are inferred from the claim text.