Patent ID: 6194916
Filing Date: 2001-02-27
Classification: G01R

Abstract:
A phase comparator for comparing phases of first and second signals with each other, said phase comparator comprising:a first control circuit for dividing a frequency of the first signal by n in response to a timing indicated by a third signal where n is an integer equal to or larger than 2;a second control circuit for dividing a frequency of the second signal by n in response to the timing indicated by the third signal; anda phase comparator unit for comparing phases of signals provided by said first and second control circuits with each other,said phase comparator being incorporated in a DLL circuit having a delaying line so that the DLL circuit determines a delay according to a phase comparison result provided by said phase comparator,wherein said phase comparator unit has a first RS flip-flop and a second RS flip-flop; said first RS flip-flop having a reset terminal to receive the signal provided by said first control circuit and a set terminal to receive the signal provided by said second control circuit, said second RS flip-flop having a reset terminal to receive the signal provided by said first control circuit through a delay circuit and a set terminal to receive the signal provided by said second control circuit, and said first and second RS flip-flops providing output signals whose combination is used to determine a phase comparison result.