Abstract: A design of a high-efficiency filtering Doherty power amplifier operating in the frequency range of 2.8 GHz~ 3.2 GHz is presented based on the CGH40025F transistor from Cree company. The cooling performance of the amplifier is analyzed using both natural convection and heat sink structures. Thermal simulations of the heat sink structure are conducted using ANSYS and COMSOL softwares to study the temperature distribution and its thermal stress and deformation. Following the simulations, the physical amplifier is constructed and tested. Experimental results show that the amplifier achieves a drain efficiency of 53.35%~69.66% and a gain of 11.8 dB~12.6 dB under saturated output power conditions within the specified frequency range. The maximum temperature recorded by the infrared thermometer on the power transistor is 97.7 ℃. Compared with the maximum temperatures of 93.25 ℃ and 92.60 ℃ obtained by ANSYS and COMSOL, the error is 4.45% and 5.22%, respectively. These discrepancies are within acceptable engineering limits, demonstrating the validity of the simulations.