using at least two phase detectors or a frequency and phase detector in the loop

Full Title

Automatic control of frequency or phase; Synchronisation > using a reference signal applied to a frequency- or phase-locked loop > Details of the phase-locked loop > concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal (H03L7/10 takes precedence; circuits for comparing the phase or frequency of two mutually-independent oscillations H03D13/00) > using at least two phase detectors or a frequency and phase detector in the loop