Mitsumi Electric Company Ltd.

Shigeki Mabuchi

Nagayoshi Dobashi

Atsushi Watanabe

Makoto Seino

Disclosed is a video signal output circuit including: a clamp circuit; a first differential amplifying circuit; a dividing circuit; and an offset circuit which adds or subtracts a predetermined offset voltage to or from a bias voltage, a reference voltage, or a base reference voltage generated by the dividing circuit so as to supply an offset voltage added/subtracted voltage to the clamp circuit or the first differential amplifying circuit, wherein the offset circuit includes a pnp bipolar transistor and an npn bipolar transistor, and outputs a difference voltage corresponding to a difference between a base-emitter voltage of the pnp bipolar transistor and a base-emitter voltage of the npn bipolar transistor.

Video signal output circuit

An image signal input circuit includes an input terminal configured to receive an image signal, a clamp circuit configured to hold a sink chip voltage contained in the image signal to be a constant value, a level shift circuit that includes a first emitter follower having a first transistor and a first current source, and a second emitter follower having a second transistor and a second current source, a base of the second transistor being connected to an emitter of the first transistor, and that is configured to shift a level of the sink chip voltage which is held constant, and an electric current source configured to attract a base current of the first transistor.

Image signal input circuit

A variable gain amplifier circuit capable of eliminating circuit elements and the area for circuits when formed into an integrated circuit is disclosed. The circuit includes plural differential circuits, one of the input terminals of each of the differential circuits being connected in common to a signal input terminal, any one of the differential circuits being selected to operate; an output circuit having an input terminal connected in common to each output terminal of the differential circuits, the output circuit inputting an output signal of any of differential circuits and outputting an output signal from the signal output terminal; and plural resistors connected in series between the signal output terminal and a reference voltage terminal, in which each of junctions between the resistors is connected to one of the other input terminals of the differential circuits.

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Tama, Japan

Shigeki Mabuchi