A new PNPN device

Several unique characteristics of a three terminal PNPN device are explained using experimental and mathematical means. When operated as a grounded base transistor, the small signal low frequency current gain (emitter to collector small signal current ratio for constant collector voltage) of this device increases with increasing d. c. emitter bias current. This current gain is unique in that there is no upper bound on its magnitude. Since the d.c. collector voltage is well below the avalanche multiplication level, multiplication is not important for this phenomenon. The responsible mechanism is determined to be the interaction between electron and hole collection resulting from the base resistance of the device. Experimental evidence is given in support of this explanation. Another characteristic of the device caused by electron-hole collection interaction is a negative slope in the collector to base terminal characteristics. This permits the device to operate as a switch under complete control of the emitter current. The switch is always returned to the off-state by removing emitter control current. Unfortunately, load current in the on-state must be limited below a definite value for complete saturation of the collector junction.