Abstract: In a transistor circuit comprising a monolithic semiconductor integrated circuit including at least one first conductivity type transistor having a base connected to a signal input terminal, a collector connected to an output terminal and also connected to a source voltage supply terminal through a collector load resistance, and an emitter connected to a reference potential through an emitter resistance, and a voltage dividing resistance circuit connected externally to the integrated circuit to establish a base-emitter biasing voltage of the first conductivity type transistor, another resistance element is provided between the source voltage supply terminal and the load resistance and a second conductivity type transistor is provided with the emitter and the collector connected to the interconnection point of the two resistances and the reference potential, respectively, and the base connected to the emitter of the first conductivity type transistor, integrating a source voltage ripple removing circuit in the

Abstract: A cascode type transistor amplifier circuit having an improved signal-to-noise ratio characteristic, wherein a parallel circuit which consists of a resistance of comparatively large value and a diode is disposed on the emitter side of one of a pair of differential transistors and wherein a variable absorption current circuit is disposed on the emitter side of a grounded-emitter amplifying transistor, the absorption current of the variable absorption current circuit being controlled so as to decrease with increase in the input signal level.

Abstract: An exhaust gas purifying system for use in an internal combustion engine for controlling the air injection into an exhaust manifold and the circulation of exhaust gases from the exhaust manifold to a suction pipe, due to a negative pressure prevailing in the suction pipe, in which the negative pressure varies depending on the running conditions of the engine.