PURPOSE: To secure a wide input output voltage range and to control the fluctuation of a characteristics due to element fluctuation by permitting an analogue switch to form a full feedback amplifier circuit instead of the differential amplifier of an open loop.

CONSTITUTION: The first full feedback amplifier circuit of the analogue switch consists of first and second transistors(Tr) 1, 2 and Tr 7 and resistors 8 and 9. A second full feedback amplifier circuit consists of Tr 3, 4 and Tr 7 and the resistors 8 and 9. Both amplifier circuits are controlled to get into an active state and an interruption state by the action of a differential couple consisting of Tr 5 and 6. The differential couple can be controlled by inputting control voltages from control terminals 22 and 23. Consequently, the input of the full feedback amplifier circuit which is in the active state by the control voltage is outputted to an output terminal 24. Consequently, the gain fluctuation of the feedback circuit can be secured and the wide input output voltage range can be secured.