Abstract: A semiconductor device is disclosed in which at least two semiconductor elements each having a self turn-off function are disposed in a package and connected in paralllel, and in which the semiconductor elements, terminals mounted on the package, and internal wirings for connecting the semiconductor elements to the terminals are arranged in geometrical symmetry, to eliminate the imbalance of current between the semiconductor elements.

Abstract: 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.

Abstract: A direct parallel connection circuit of gate turn-off thyristors wherein a plurality of GTO's having different current capacities are directly connected in parallel. A turn-on gate current and a turn-off gate current are passed to the gate of each of GTO's through a resistor and a reactor, respectively so as to substantially simultaneously turn-on and turn-off GTO'S, respectively.

Abstract: 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.

Abstract: 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.