PURPOSE: To eliminate simply a spike of a D/A converter output waveform, without addition of a deglitcher circuit, by controlling a sampling gate for a period settled with the D/A conversion output.

CONSTITUTION: In a low-pass filter 3 obtaining an analog output through the sampling and averaging an output A of a D/A converter 1, sampling gates 31, 32 across a capacitor C are turned on and off with an inverting signal via an inverting circuit 5 and an output of an AND gate 6, the D/A conversion output A is sample-held and given to a smoothing circuit after an operational amplifier 33. The AND gate 6 is set on with a gate pulse B so as not to output a sampling pulse C while the D/A conversion output A is not settled.