Ic having an output signal amplitude kept constant against temperature

Abstract

In an integrated circuit having first (VDD) and second (GND) power terminals, a differential amplifier has a load end connected to the first power terminal to produce-in response to an input signal (IN(1)-IN(2)) an output signal (OUT(1)-OUT(2)) when a common connected end of the amplifier is connected through an n-type constant current transistor (19) to the second power terminal. Connected between the power terminals, a bias resistor (25) and an n-type bias transistor (27) produces a bias circuit output voltage for comparison with a reference voltage (REF) by a voltage comparator (29) for producing a difference voltage which is delivered to a constant current transistor gate electrode and fed back to a bias transistor gate electrode to keep an amplitude of the output signal constant against a temperature variation. It is possible to use as the reference voltage a divided voltage of a source voltage supplied between the power terminals. If p-type transistors are used, the source voltage should have a reversed polarity.