PURPOSE: To obtain a noise-free circuit which can control the duty of an output to 50% or controls outputs independently by providing an oscillator with 1st and 2nd constant current sources, a control circuit controlling the 1st and 2nd current sources and a means intermittently connecting and cutting the 1st and 2nd current sources.

CONSTITUTION: A P channel MOS transistor (hereinafter referred to PchTR) 23 is a current mirror for a current source PchTR 22. An NchTR 34 is a current mirror for NchTRs 32 and 33 and its current value is decided by a current source 40. The titled oscillator is constituted by providing a circuit consisting PchTRs 21 and 22 and NchTRs 31 and 32 with an inverter 13. As for the action, the PchTR 21 is turned on with the output of an inverter 11 at a low level, and a capacitor 50 is charged. With the output of the inverter 11 at a high level, the NchTR 31 is turned on to discharge the capacitor 50, and a target triangle wave can be obtained. Thus an inverter 12 can obtain an output waveform with a duty of 50%.