In this paper, a compact broadband amplifier is realized based on 65nm CMOS technology. The three differential CMOS pairs adopt the common source (CS) structure, rely on the capacitance neutralization technology and use the transformer for impedance transformation to achieve ultra-wideband matching. The simulation results show that in FR2 frequency band (24.26 - 52.6GHz), the output gain of the amplifier is 17±2.5dB, the DC power consumption is 45mW, the supply voltage is 1V, and the core circuit area is 0.11mm2.