Phase comparator with improved comparison precision and synchronous semiconductor memory device employing the same

摘要

The phase comparator receives an output of a buffer receiving the first input signal and an output of a buffer receiving the second input signal, and outputs signals SLOW, FAST as a result of phase comparison. The phase comparator includes a waveform processing circuit for enlarging the phase difference between two input signals, and a comparison circuit for performing phase comparison based on the phase difference enlarged by the waveform processing circuit and outputting signals SLOW, FAST. Because of the function of the waveform processing circuit, the performance of the phase comparator can be improved significantly, without having to largely improve the performance of the comparison circuit.