Thermal design of microwave power amplifiers based on GaAs HBTs

In this paper, a novel type of thermal shunt structure in layout design is proposed to optimize the thermal distribution of microwave power amplifiers based on GaAs HBT process. The collector metal is introduced to provide a new heat dissipation path from the power cells of the chip to the ground. The simulation results show that, by increasing this cooling path, the maximum temperature of the power cells is effectively reduced from 163°C to 148°C when the circuit is working normally. In order to ensure the RF performance of the amplifiers, Metal 2 involved in the new heat dissipation path is in the shape of fingers, which can minimize the coupling parasitic capacitance.