Hitachi, Ltd.

Hitachi Haramachi Semi-conductor, Ltd.

Hitachi Engineering Co., Ltd.

Haramachi Semi-hitachi Ltd.

Hitachi Conductor Ltd.

Hitachi Ltd. and Hitachi Haramachi Semi-conductor Ltd.

Tatsuo Shimura

Tadaaki Kariya

Sigeo Tomita

Shigeru Sugayama

Mitsuhiko Okutsu

Masayuki Wada

Masato Miura

Chooji Shiina

Tadaki Kariya

Norihiro Kawauchi

Kazuyoshi Masuda

Sinichi Kurita

A lateral-type semiconductor device is provided in which a p-emitter layer and a p-collector layer are formed on the exposed-surface side of an n-base layer. The exposed surfaces of the p-emitter layer and the n-base layer are substantially surrounded by the exposed surface of the p-collector layer. The n-base layer is connected to a base electrode or through a first heavily-doped region extending from under the n-base region to an exposed surface area on the outer-periphery side of the p-collector layer. In an alternative embodiment a second heavily-doped region for connecting the n-base layer and the first heavily-doped region can be provided.

Lateral-type semiconductor device

A fraction of current passing through the P-emitter region and N-base region of a thyristor is by-passed to the base-emitter junction of a PNP transistor. The amount of the base current is dependent on the thyristor current. Thus, as the anode current of the thyristor increases, the base current and hence the collector current of the PNP transistor increases. The collector current by-passed to the PNP transistor is fed, via a switch which is closed during the off-time of the thyistor, to the base-collector path of an NPN transistor whose collector and emitter are respectively connected to the gate and cathode of the thyristor. The turn-on voltage across the collector and emitter of the NPN transistor accordingly becomes lower than the gate-cathode voltage of the thyristor. The base-emitter current of the NPN transistor equals the collector current of the PNP transistor, the collector current being a fraction of the anode current by-passed to the PNP transistor. A fraction of the anode current of the turned-on thyristor is utilized as the control power for driving the NPN transistor so that additional external power for turning off the thyristor becomes almost unnecessary.

Semiconductor switching circuit

A turn-off control circuit for a gate turn-off thyristor is used in a state where one end of an inductive load is connected therewith on the cathode side. The turn-off control circuit includes a first turning-off transistor, which takes-out electric current through the gate at the first stage of the turn-off operation of the gate turn-off thyristor, and a second turning-off transistor, which takes-out electric current through the gate at the second stage of the turn-off operation of the gate turn-off thyristor so as to surely effect the turn-off operation.

Turn-off control circuit for a gate turn-off thyristor

A voltage across a resistor of a small value connected in series with the cathode or anode of a thyristor is used as a signal source for overcurrent detection. When an overcurrent is generated, the voltage across the resistor increases in excess of the built-in voltage between the base and emitter of a transistor, thereby turning on the transistor. A transistor to take out a current from the gate of the thyristor is turned on. Thus, the self-turn off operation of the thyristor is executed.

Semiconductor switch

A device for driving a capacitive load, comprising a first switching element responsive to an external control signal for selectively conducting a charge current therethrough to the load, a second switching element responsive to the external control signal for conducting a discharge current from the load and a generator for generating from the discharge current a cutoff signal to be applied to the first switching element to ensure turn-off of the latter.

Capacitive load driving device

In a bidirectional linear switch in which two MOS transistors are used with their sources mutually connected, the gates and the substrates of the transistors are also respectively mutually connected and a control signal is applied to the gates. A potential of the polarity such that the substrates are reversely biased to the sources is applied between the substrates and the sources. With this constitution, the linearity of the bidirectional switch is improved.

Bidirectional MOS linear switch

A reference voltage circuit in which an output reference voltage is stabilized against variations in power source as well as in transistor current amplification factor h.sub.FE. In a reference voltage circuit comprising a DC power source connected to an output terminal, first and second resistors with their respective one ends commonly connected to the output terminal, a first NPN transistor with its collector shorted with its base and connected to the other end of the first resistor and its emitter grounded, a second NPN transistor with its collector connected to the other end of the second resistor and its base connected to the collector of the first NPN transistor, a third resistor connected between the emitter of the second NPN transistor and the ground, and a third NPN transistor with its collector connected to the output terminal, its base connected to the collector of the second NPN transistor and its emitter grounded, there are further provided a fourth resistor connected between the collector of the third NPN transistor and the output terminal and a PNP transistor with its base connected to the collector of the third NPN transistor, its emitter connected to the output terminal and its collector grounded.

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Hitachi, Japan

Tatsuo Shimura