A 36-40 GHz 4-element Tx and Rx beamformer chip set for the fifth generation communication millimeter wave (5G mm-Wave) phased-array applications is presented in this paper. The separated Tx/Rx beamformer chips have 4-bit (22.5°) phase control with 25° phase compensation, and 40 dB peak gain per channel with 20 dB gain control. All of the gate biases, gain and phase tuning functions are controlled by the mixed-signal integrated circuits embedded in the chips, programmable by the microcontroller. The chips are fabricated using TSMC 65-nm CMOS process. The measured O P i d B per channel of the Tx beamformer is 12 dBm, and NF (noise figure) of the Rx beamformer is 6-9 dB. The Tx/Rx beamformers measurements performed less than 2 dB RMS gain error and 5.5 0 RMS phase error with 360° phase tuning, and ±5° phase variation with 20 dB gain tuning. To the author's knowledge, these chips are the first beamformers in 65-nm CMOS for the FCC 5G mm-Wave 37 GHz (37-38.6 GHz) and 39 GHz (38.6-40 GHz) phased-array applications. This chip set will be the unit cell to be integrated with antenna arrays to construct 32 or 64-element phased-array systems in the near future.