Modeling of an InGaP/GaAs BiFET VVR Device

A recently introduced InGaP/GaAs BiFET process allows the integration of a JFET device with a standard HBT process. This JFET device, also called a voltage variable resistor (VVR), can be utilized in bias control circuits on the same die as HBT power amplifiers. An innovative modeling solution was developed to simulate temperature and surface state mechanisms related to device performance. For this modeling work, a parasitic FET model is used for surface state effects along with a dual diode model for voltage dependent ideality. Using these techniques, accurate simulations can be made to design near device limitations.