Abstract: A phase-locked loop circuit is disclosed for use, for example, in the data recovery system of a rotating magnetic disk drive unit employing a phase encoded signal format. The phase-locked loop circuit has a dual mode of operation wherein captive range is assured by providing a first frequency locking mode of operation wherein a voltage controlled oscillator (VCO) is first locked in frequency to a reference signal and a second phase locking mode of operation wherein the VCO is subsequently locked in phase to an MFM signal independently of the frequency assumed by the latter signal. In addition to the VCO, the phase-locked loop circuit includes a frequency detector, a phase detector, a filter, an amplifier, a pair of frequency dividers, a pulse shaping network and a plurality of switches. A potentiometer is coupled to the input of the amplifier and is used to supply a voltage signal to the amplifier which is sized to offset system phase errors caused by the various components in the phase-locked loop circuit.