Diodes Incorporated
BIPOLAR JUNCTION TRANSISTOR HAVING AN INTEGRATED SWITCHABLE SHORT

Abstract:

The invention solves the problem of depressed SOA of a bipolar junction transistor (BJT) when operated in an open base configuration by integrating in the same semiconductor chip a switchable short between the base and the emitter of the BJT. The switchable short switches between a high resistive value when the collector voltage of the BJT is lower than the base voltage. and a lower resistive value when the collector voltage is higher than the voltage base to effectively lower the BJT current gain (h.sub.FE). The switchable short in one implementation of the invention is in the form of a MOSFET with its gate connected to the BJT collector. The invention further teaches disposing in the integrated circuit chip a junction diode with a breakdown voltage lower than the BVCBO of the BJT. The addition of the junction diode provides a measure of maintaining the effectiveness of the MOSFET as switchable short at a reduced size.