Northrop Grumman Systems Corporation

Ken K Tsai

Gerald R Fischer

Talley J Allen

A phase locked loop ( ) for generating a variable output frequency signal. The phase locked loop ( ) includes a controlled oscillator ( ) to generate the variable output frequency signal in response to a tune signal. A phase detector ( ) is activable in response to a gating signal ( ) to generate an error signal representing a difference between a reference frequency signal and the variable output frequency signal. A loop filter ( ) having a filter characteristic, filters the error signal and generates the tune signal. An offset cancellation circuit ( ) is coupled to the loop filter ( ). In response to an error signal representing phase offset of the phase locked loop ( ), the offset cancellation circuit ( ) supplies a compensating signal to reduce the phase offset.

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Palos Verdes Estates, CA, United States of America

Ken K Tsai