Patent ID: 6940931
Filing Date: 2005-09-06
Classification: G06F

Abstract:
1. A clock-synchronism evaluating apparatus comprising: a measurement section that measures a difference between a predetermined phase point of a first clock signal and a predetermined phase point of a second clock signal, wherein said measurement section generates a measuring gate pulse that rises in synchronism with one of said first and second clock signals and falls in synchronism with other of said first and second clock signals, said measurement section measuring a pulse width of the generated measuring gate pulse by counting clock pulses higher in frequency than said first and second clock signals; and a determination section that determines whether or not frequencies of said first clock signal and said second clock signal are the same, on the basis of a variation over time of the difference measured by said measurement section, wherein said determination section determines that the frequencies of said first clock signal and said second clock signal are, the same when counted values indicative of respective pulse widths of an adjacent pair of the measuring gate pulses generated in succession coincide with each other, but determines that the frequencies of said first clock signal and said second clock signal are not the same when the counted values of the adjacent pair of the measuring gate pulses do not coincide with each other.