Bbc Brown, Boveri & Company, Limited

Patrick DeBruyne

Roland Sittig

A high frequency, high voltage thyristor and an associated circuit arrangement and method of operating the circuit are disclosed. The thyristor, which is capable of switching frequencies above 10 kHz and forward blocking voltages in excess of 500 V. includes an inter-digitated emitter-gate structure, a control zone in contact with the gate and a base zone that is less doped than the control zone. The base zone of the thyristor includes first and second layers of different doping concentrations. The circuit arrangement includes thyristors of the type described arranged in pairs and shunted by antiparallel diodes. According to the method of the invention, the thyristor is not fired by applying potential to the gate, but by holding the thyristor in a forward blocking state and then opening the gate circuit or reversing the gate voltage.

Electrical circuit with a high-frequency thyristor fired by blocking

A thyristor, with at least four zones of alternating opposite conductivity types, in which the first and fourth zones are contacted by the main electrodes and act as emitter zones, the second zone adjoins the first zone, and the third zone of lowest doping lies between the second and fourth zones. Both the second and the third zones together with the forward blocking PN-junction formed between them extend to the surface of the thyristor semiconductor chip on the side with the first zone. The portion of the forward blocking PN-junction reaching the surface can be irradiated with light so as to trigger the thyristor. There is provided in the surface a highly doped zone of the conductivity type of the first zone, which is connected with the second zone by an electrical contact on the surface. The part of the third zone extending to the surface encloses part of the second zone and the highly doped zone. The electrical contact connects the highly doped zone with the part of the second zone lying outside the region of the second zone enclosed by the third zone at the surface.

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Siggenthal, Switzerland

Patrick DeBruyne