A semiconductor device, comprising a transistor, a constant voltage diode having a first end of a first conductivity type connected to an emitter of the transistor and a second end of a second conductivity type, a reverse current preventive diode having a first end of the first conductivity type connected...http://www.google.com.au/patents/US5469103?utm_source=gb-gplus-sharePatent US5469103 - Diode circuit for high speed switching transistor
