PHASE DETECTOR AND PHASE LOCKED LOOP

摘要

A phase detector is provided, for example for use in a phase locked loop in a frequency synthesizer. The phasedetector comprises a phase-frequency detector (2) providing output pulses (UP, DN), whose widths represent the relative frequencies and phases of input signals (F REF, F VCO). The output pulses are supplied to a pulse width to current converter (15, 16), which continuously supplies a direct output current to the output (VCO control) of the phase detector. The direct output current is a function of the pulse widths of the pulses (UP, DN) from the phase-frequency detector (2).