Hitachi, Ltd.

Pioneer Electronic Corporation

Toshihide Hanada

Yasuo Kominami

Masahiro Yamamura

Katsuji Mizumoto

This invention relates to a constant voltage output circuit using, as its reference potential source, power source feed terminals for feeding a power source voltage to a reference potential source of a given circuit. The constant voltage output circuit includes a series circuit of an npn transistor and a pnp transistor interposed between the reference potential source of the given circuit and the power source feed terminals, means for biasing the base potential of the pnp transistor by a predetermined potential with respect to the potential of the power source feed terminals, and an emitter follower circuit disposed in the collector output circuit of the npn transistor of the series circuit, and forming a negative feed-back circuit.

Constant voltage output circuit

The present invention is related to a temperature-compensated circuit for controlling the drive of a motor, comprising a differential comparator for comparing a running-speed signal of a motor with a reference signal, and a feedback amplifier having a differential amplifier to which is given an input offset.

Circuit for controlling the drive of motor

A differential amplification is disclosed which comprises differential paired transistors. The direct bias current flowing in the differential paired transistors is determined by a constant current flowing from a first constant current circuit connected to the emitters of the differential paired transistors. The collector current of one of the differential paired transistors is caused to flow as an input current in a high-precision current mirror circuit. The current value of the constant current flowing in the first constant current circuit is set at 2Io. Since a direct base current Ib flows in the differential paired transistors, the current value of the collector current of one of the differential paired transistors is (Io-Ib). Accordingly, the high-precision current mirror circuit generates an output current of a current value of (Io-Ib) at the output terminal thereof. The differential amplification circuit includes a second constant current circuit having a current value Io corresponding to 1/2 of the current value of the constant current flowing in the first constant current circuit. A bias transistor is connected between the high-precision current mirror circuit and the second constant current circuit, and the direct base current Ib flows in this bias transistor. Accordingly, in the equilibrium state between the differential paired transistors, the output current appearing at the output terminal of the high precision current mirror circuit becomes zero, and the offset output current can be eliminated or moderated.

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Sayama, Japan

Toshihide Hanada