US 5,493,253 AGranted

IC having an output signal amplitude kept constant against temperature variation

AssigneeNEC Corporation

InventorShin-ichi Ogou

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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.

Claims4

Dependent claims

A semiconductor integrated circuit, comprising:

first and second input terminals;
first, second, third and fourth nodes;
first and second power lines;
a first output terminal connected to said first node;
a first transistor having a source-drain path connected between said first and third nodes and having a gate connected to said first input terminal;
a second transistor having a source-drain path connected between said second and third nodes and having a gate connected to said second input terminal;
a first resistor connected between said first power line and said first node;
a second resistor connected between said first power line and said second node;
a third transistor having a source-drain path connected between said third node and said second power line and having a gate;
a third resistor connected between said first power line and said fourth node;
a fourth transistor having a source-drain path connected between said fourth node and said second power line and having a gate connected to the gate of said third transistor;
and
an operational amplifier having a non-inverting input node connected directly to said fourth node, an inverting input node provided with a reference voltage, and an output node connected to the gate of said third transistor.

10 more elements

Dependencies are inferred from the claim text.