Abstract: Based on SMIC 55nm CMOS technology, a 2~8 GHz UWB high linearity direct down-conversion passive mixer structure was proposed based on current mode structure. The main structure of this design was arranged according to the LNTA-Passive Mixer-TIA structure, taking a Low Noise Transconductance Amplifier (LNTA) to drive I/Q two-channel current mode passive mixer with a low input impedance Trans-impedance Amplifier (TIA) as load. Making use of capacitive cross-coupling and double-end feedback structure, the LNTA was designed to solve the compromise problem of key parameters such as impedance matching and noise. The whole receiver link was arranged to achieve better linearity and noise performance, and improve the robustness of the power supply voltage and substrate noise. The simulation results show that under 1.2 V power supply voltage, the following results can be obtained, 2~8 GHz RF input signal frequency, −5.5 dBm linearity for 1 dB compression point input, −1 dBm in-band input third-order crossover point, 4 dB overall noise factor, and 0.12 mm² core layout area.