Abstract: An integrated circuit for protecting subscriber lines against overvoltages includes a semiconductor body; a field-controllable thyristor having a gate electrode, an anode electrode and a cathode electrode, the gate electrode being insulated from the semiconductor body; a resistor connected between the cathode electrode and the gate electrode; a series circuit of Zener diodes connected between the gate electrode and the anode electrode, each of the Zener diodes having an anode electrode and a cathode electrode; and short circuit jumpers each being connected between the anode electrode and the cathode electrode of a respective one of at least part of the Zener diodes; at least part of the jumpers being interrupted corresponding to a predetermined breakdown voltage of the series circuit; and the thyristor having a larger breakdown voltage than the combined breakdown voltages of the Zener diodes of the series circuit of Zener diodes.

Abstract: A thyristor comprising a semiconductor element is described which has at least four zones of alternate conductivity type with a shunt between an outer zone which serves as an emitter and an adjacent inner zone which serves as a base. A strip shape control electrode is arranged along one edge of the adjacent zone, and an emitter electrode is arranged in contact with substantially all of the outer surface of the emitter. The emitter electrode is provided with a large number of openings arranged in a regular pattern, through which openings portions of the adjacent zone extend into contact with the emitter electrode. The emitter openings are located at the intersection points between first lines running parallel to one another on the one hand, and at second lines which are repeated in a regular sequence parallel to one another and inclined toward the emitter electrode at an angle .theta. which is less than 90.degree. and greater than 45.degree..

Abstract: The present invention pertains to a thyristor device comprising a semiconductor body having at least one emitter zone positioned at a major surface of the body. A base zone shares a portion of the major surface with the emitter zone and extends under the entirety of the emitter zone. The base zone and emitter zone form a PN junction at their interface. The portion of the base zone under the emitter zone has a plurality of low resistivity branches which have their common origin in the portion of the base zone located directly under the major surface.