Electronic components
Sources of terahertz electromagnétic radiations

Electronic components such as Gunn, RTD or IMPATT diodes can exhibit Negative Differential Resistance (NDR). The origin of NDR lies in specific electronic transport properties in the semiconductor material or device. Thus, their current-voltage curve I (V) is no longer linear (ohmic behavior), but shows a secondary maximum (figure 6a). The negative slope of the I (V) curve after the maximum corresponds to a resistance R (called differential) which is negative (R = dV /dI). When this NDR component is inserted in an RLC circuit, the differential current equation and its solution are written as :