A post-linearization technique for the differrential CMOS LNA is presented. The proposed method uses an additional cross-coupled common-source FET pair to cancel out the third-order intermodulation ($IM_3$) current of the main differential amplifier. This technique is applied to enhance the linearity of CMOS LNA using $0.18-{mu}m$ technology. The LNA achieved +10.2 dBm IIP3 with 13.7 dB gain and 1.68 dB NF at 2 GHz consuming 11.8 mA from a 1.8-V supply. It shows IIP3 improvement by 6.6 dB over the conventional cascode LNA without the linearizing circuit.