A surface-controlled negative impedance transistor

A negative impedance transistor is described in which a gate on the oxide over the emitter-base junction and attached to the collector causes the collector current ICto decrease when VCEexceeds a critical value. For high VCE, ICeventually increases as breakdown is reached. When operated with a fixed external base current drive, the IC- VCEcharacteristic is similar in shape to the I-V characteristic of a tunnel diode. The ratio of the peak-to-valley current, and the voltage range over which the negative impedance effect occurs, are shown to be strongly dependent on the base surface concentration, oxide thickness, and the external base current drive. Two models are presented which predict the variation in the base current with gate voltage in terms of base surface recombination and surface potential. These models may be extended to describe the variation in ICwith VCEfor a constant external base current drive. Two sample applications of the gated transistor are presented.