A 90 GHz power amplifier for high output power with 26 GHz 3-dB bandwidth is proposed and fabricated using 65-nm CMOS technology. A 16-way power-combining structure is developed, which combines the transistors and transfers the impedances simultaneously. The design methodology of the dc bias network is also presented to feed the high dc current into the multi-way combining structure under the geometric limitation. Based on these techniques, this power amplifier achieves saturation power 18 dBm with 12.5-dB small signal gain. To the authors' knowledge, this power amplifier achieves the highest output power among the reported CMOS PAs at this frequency.