By using 0.15 μm GaAs pHEMT (pseudomorphic high electron mobility transistor) technology,a design of millimeter wave power amplifier microwave monolithic integrated circuit (MMIC) is presented.With careful optimization on circuit structure,this two-stage power amplifier achieves a simulated gain of 15.5 dB with fluctuation of 1 dB from 33 GHz to 37 GHz.A simulated output power of more than 30 dBm in saturation can be drawn from 3 W DC supply with maximum power added efficiency (PAE) of 26%.Rigorous electromagnetic simulation is performed to make sure the simulation results are credible.The whole chip area is 3.99 mm2 including all bond pads. By using 0.15 μm GaAs pHEMT (pseudomorphic high electron mobility transistor) technology, a design of millimeter wave power amplifier microwave monolithic integrated circuit (MMIC) is presented. At careful optimization on circuit structure, this two-stage power amplifier achieves a simulated gain of 15.5 dB with fluctuation of 1 dB from 33 GHz to 37 GHz. A simulated output power of more than 30 dBm in saturation can be drawn from 3 W DC supply with maximum power added efficiency (PAE) of 26%. To make sure the simulation results are credible. The whole chip area is 3.99 mm2 including all bond pads.