Comprehensive thermal analysis of pulsed GaAs HPAs for lifetime estimation

In pulsed applications, such as radar, estimates of FET channel temperature based on time-averaged modeling are inaccurate; the analysis must be done dynamically. A thermal model of an X-band power amplifier is constructed and validated against direct measurements by time-resolved Raman thermography, complemented by laser thermo-reflectance and infrared imaging. The consequences for radar system design are discussed, including the impact of RF drive on channel temperatures. A comparison of device lifetime based on instantaneous and time-average channel temperature is presented.