Direct measurement of thermal circuit parameters using pulsed IV and the normalized difference unit

Abstract

New methods are presented for direct extraction of thermal resistance and capacitance from pulsed IV measurements. Because thermal effects are frequency dependent, a thermal circuit is used in many models to characterize the device channel temperature as a function of frequency. Thermal resistance is determined using pulsed IV data sets taken at varied ambient temperature, while the thermal capacitance is found through use of a new normalized difference unit (NDU) for IV data. Determination of thermal subcircuit parameters from readily available pulsed IV measurements reduces the complexity of electrothermal model development for microwave transistors.