Delay circuit with muting to prevent noise due to random data at output

Abstract

A delay circuit includes a memory addresses of which is designated by a counter incremented in response to each clock signal from an initial value set by an initial value setting circuit to an end value. A digital signal is written into an address as designated and read and converted into an analog signal to be outputted at an output terminal through a buffer amplifier. A delay time is determined by the writing timing and the reading timing of the digital signal. If the delay time is to be varied in the course of a delaying operation, a further initial value is set in the counter. A control signal for returning the counter in the initial value is generated by a first signal generating circuit when the end value is reached and a setting completion signal is generated by a second signal generating circuit when a setting of the further initial value is completed, and in response to both the signals, a muting signal is generated by a muting signal generating circuit, whereby the buffer amplifier mutes the output signal in response to the muting signal to prevent a noise due to random data from occurring at the output terminal.