Abstract

Most contemporary semiconductor devices exhibit dynamic I (V )behaviour that is different from the static (or dc)behaviour -in some cases markedly different.Commercial fast-sampling dynamic curve tracer instrumentation shows how devices ranging from diode structures to pseudomorphic high electron mobility transistors (PHEMTs)and heterojunction bipolars (HBTs)will behave in practical RF circuits.Examples of dynamic behaviour include the inability to cut-off some HBTs, which may lead to the power-added efficiency being highest at low supply voltages;highly non- diode-like flow of gate current and negative drain current flow in E-mode GaAs FETs;broadband negative differential conductivity in some PHEMTs,which complicates the circuit designers job of achieving stable circuits;the reduction of dispersion in high-voltage SiC FETs,and,by analysis of drain current transients,separation of the percentage contributions to dispersion in FETs and HEMTs made by deep levels and self-heating as a function of bias and operating point.