A wideband 120-GHz up-conversion mixer for high-speed chip to chip data communication is presented in a 40 nm CMOS process. Using a negative feedback resistor and PMOS transistor at transconductance stage of mixer, the conversion gain and bandwidth are both enhanced. According to the measurement results, the proposed mixer achieves a maximum conversion gain of −3.5 dB and a 3-dB bandwidth of 26-GHz at low local oscillator (LO) drive power of -4-dBm. The power consumption is only 8-mW at 0.9-V supply voltage.