A three-stage differential common source structure is used to design a W-band power amplifier based on 65-nm CMOS technology, and two way current-mode power combining structures are used for power combining to increase output power.In order to achieve single-ended to differential conversion, impedance matching, and DC power supply at the same time, the matching network adopts a transformer structure.The simulation results show that under a supply voltage of 1 V, the power amplifier has a small signal gain of 12.7 to 15.7 dB, a 3-dB bandwidth of 84 to 104 GHz, a saturated output power of 14.6 dBm, and a peak power added efficiency of 9.7%.The power amplifier has good large signal performance, and the core area of the chip is only 0.115 mm².