Abstract: A control signal that runs a control oscillator of a signal generation circuit that generates a write clock is taken as a reference signal. That reference signal is supplied to a signal generation circuit that generates a read clock. In the signal generation circuit that generates the read clock, there is no need to generate a reference signal within its own circuits, which makes it possible to supply it to a control oscillator by adding the error timing from reading out the signal against the supplied reference signal. In this way, no means for locking the read clock into the initial frequency is needed and neither is the time for locking the read clock to the initial frequency (lock up time). This makes it possible to reduce the size of the circuit and to reduce the signal read-out time.

Abstract: A Digital/Analog converter comprising a plurality of current sources, and a selecting circuit for selecting a current source from the plurality of current sources on the basis of a digital signal. The selecting circuit includes a first transistor in which the digital signal is supplied. The selecting circuit also includes a second transistor with the same conductivity type as the first transistor for receiving an inverted digital signal of the digital signal. The second transistor is connected to the output of the first transistor.