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US 5,848,265 AGranted
Circuit and method for measuring the difference frequency between two clocks
AssigneeCypress Semiconductor Corporation
InventorsMichael F. Maas, Bret A. Oeltjen
Life of this patent
Estimating the term…
Abstract
A circuit for measuring the frequency difference between a reference clock and a second clock. The circuit presents a first output in response to a phase crossing between the two clocks. A second circuit presents a second output in response to the first output and the reference clock.
Claims20
A circuit comprising:
- a first circuit configured to present a first output in response to (i) a first clock and (ii) a second clock, wherein said first output represents a phase crossing of said first and second clocks;
- and
- a compare circuit configured to present a second output in response to (i) said first output and (ii) a reference clock.
A circuit comprising:
- means for generating a first output in response to (i) a first clock and (ii) a second clock, wherein said first output represents a phase crossing of said first and second clocks;
- and
- means for generating a second output in response to (i) said first output and (ii) a reference clock.
A method for determining the frequency difference between first and second clocks comprising the steps of:
- generating a first signal in response to a phase crossing of a first clock and a second clock, wherein said first signal has a state changing in response to said first and second clocks;
- and
- generating a second signal representing the frequency difference between said first and second clocks in response to a comparison of said first signal and a reference clock.
Dependencies are inferred from the claim text.