Abstract: Disclosed is a frequency multiply circuit for outputting an output signal obtained by variably multiplying the frequency of an input signal includes a synchronous delay circuit, a multiplexing circuit, and a control circuit. The synchronous delay circuit includes a period measuring delay circuit for measuring the period of the input signal and delay reproducing delay circuits each with a delay time thereof variably set based on the period measured by the period measuring delay circuit, for respectively reproducing the delay time. The multiplexing circuit receives a plurality of signals of different phases output from the synchronous delay circuits, for multiplexing. The control circuit variably sets the number of the delay stages of the period measuring delay circuit and the numbers of the stages of the delay reproducing delay circuits, according to the set frequency-multiplication factor.

Abstract: Disclosed is a frequency multiply circuit for outputting an output signal obtained by variably multiplying the frequency of an input signal includes a synchronous delay circuit, a multiplexing circuit, and a control circuit. The synchronous delay circuit includes a period measuring delay circuit for measuring the period of the input signal and delay reproducing delay circuits each with a delay time thereof variably set based on the period measured by the period measuring delay circuit, for respectively reproducing the delay time. The multiplexing circuit receives a plurality of signals of different phases output from the synchronous delay circuits, for multiplexing. The control circuit variably sets the number of the delay stages of the period measuring delay circuit and the numbers of the stages of the delay reproducing delay circuits, according to the set frequency-multiplication factor.

Abstract: An input buffer circuit having a function to detect whether or not a cable is connected includes a differential circuit for receiving differential data having first data and second data, and changing a signal level of an output signal when a difference between a signal level of the first data and a signal level of the second data exhibits a predetermined value. The input buffer further includes a conversion circuit for matching the signal level of the output signal to a specific band level.

Abstract: A first latch circuit latches output data in response to a leading edge of a clock signal. A second latch circuit latches the output data in response to a trailing edge of the clock signal. When the first latch circuit latches a low level, an n-channel MOS transistor is turned to an on-state in order to supply the transmission path to the low level. When the first latch circuit latches a high level, a p-channel MOS transistor is turned to an on-state during a period during which the second latch circuit latches the low level. The transmission path is supplied to thq high level.