A high voltage, high speed, three terminal PNPN switch

The design of high voltage, high speed, three terminal silicon P PN switches for high pulse current applications is discussed. The resistivity of the region and the minimum base widths are determined by the minimum breakover voltage requirement. The dependence of the delay and turn on times and trigger requirements on the two base widths is then analyzed. It is pointed out that the breakover voltage, speed, and peak current requirement in combination with the desire for a low "on" drop necessitates stringent control of the resistivity of the v material during processing. The emitter area and emitter contact sheet resistance are determined by the peak current requirement. Other design features of the device are also discussed. Representative values of the device parameters are given for various designs. In typical applications, the devices are capable of switching from 500 volts to 50 amperes with turn-on times of .05 µsec.