The NEGIT: A surface-controlled negative impedance transistor

A Negative impedance transistor (NEGIT) is realized by controlling base surface recombination in a bipolar transistor by biasing a gate on the oxide over the emitter-base junction. This gate is attached to the collector by conventional metallization. As VCEincreases, the active region is robbed of base current causing ICto decrease. It is shown theoretically, and confirmed experimentally, that both the magnitude of the effect and the voltage range over which the negative resistance occurs, depend strongly on base oxide thickness and base surface doping, and are dominated by the base surface immediately adjacent to the emitter-base junction. Thus very small area devices are possible in both discrete and IC versions, for either high or low voltage operation, with only minor changes in existing technology. Although only sample applications are shown, and frequencies employed only up to 11 MHz, a wide variety of applications are possible.