High-Speed Electro-Thermal Measurements in RF Power Amplifiers Using Thermo-Reflectance

The methodology presented here provides a route for directly performing high-speed electro-thermal characterisation on a Power Amplifier (PA) using Thermo Reflectance method. Starting the analysis with RF pulses, the PA electrical and thermal behaviour at different ambient/baseplate temperatures and dissipation profiles is measured with the presented setup. After this, the on-chip intra-finger temperature of this PA, based on a GaN-on-SiC Wolfspeed CG2H40010F transistor, is measured by considering high-PAPR signals with bandwidths of 10 kHz, 100 kHz, and 10 MHz. For the 10 MHz modulated signal, no in-signal temperature fluctuations are observed during the amplification, whereas for 10 kHz a maximum variation of +/- 7 degrees C and +/- 3 degrees C for a 100 kHz signal is measured.