Negative Resistance

Negative resistance is a property of some electric circuits where an increase in the current entering a port results in a decreased voltage across the same port. This is in contrast to a simple ohmic resistor, which exhibits an increase in voltage under the same conditions. Negative resistors are theoretical and do not exist as a discrete component. However, some types of diodes (e.g., tunnel diodes) can be built that exhibit negative resistance in some part of their operating range. Such a differential negative resistance is illustrated in Figure 1 with a resonant-tunneling diode. Electric discharges through gases exhibit negative resistance, and some chalcogenide glasses, organic semiconductors, and conductive polymers exhibit a similar region of negative resistance as a bulk property. In electronics, negative resistance devices are used to make bistable switching circuits, and electronic oscillators, particularly at microwave frequencies