PHASE DIFFERENCE DETECTOR AND PHASE DIFFERENCE DETECTING METHOD

摘要

A phase difference detector detects a phase difference between input clocks both having the same first frequency. The phase difference detector comprises a pulse width converting section for converting the phase difference between the input clocks into a phase difference signal shown in a pulse width to the input clocks and a counter section for sampling the levels of the phase difference signal by using a reference clock having a second frequency slower than the first frequency and counting the number of levels of the phase difference signal by a first weight corresponding to the sampled levels of the phase difference signal. When the value counted by the counter section remains within a constant range, the phase difference between the input clocks is detected by the first weight.