Patent ID: 6982579

Claim:
A method of maintaining a desired phase relationship between a generated periodic signal and a periodic reference signal, said method comprising: generating a first periodic signal with a first delay line and a second periodic signal with a second delay line, each delay line comprising a plurality of unit delays connected in series, the number of unit delays involved in said generating being selectable by digital signals, the difference between said selected number of unit delays in said first delay line and in said second delay line being at least one unit delay; phase mixing said first and said second generated periodic signals according to an adjustable phase mixing ratio to produce a phase-mixed signal; measuring a phase difference between said periodic reference signal and said phase-mixed signal after a plurality of cycles of said phase-mixed signal; adjusting if necessary at least one of said phase mixing ratio and said number of unit delays in at least one of said first and said second delay lines based on said phase difference and said desired phase relationship; and generating said first and second periodic signals after said adjusting.