A highly linear X-band low-noise amplifier (LNA) is proposed and implemented in a standard 0.18- $\mu \text{m}$ CMOS technology. The LNA features both high- and low-gain operation modes. In its normal high-gain mode, the LNA shows a small-signal gain of 13.6 dB with an IIP3 of +9.5 dBm and a noise figure of 4.7 dB. The two-stage amplifier draws 90 mA from the 3.3-V power supply to achieve +14.8 dBm output P1dB (+2.2 dBm input P1dB). In the low-gain mode, the gain is reduced by about 10 dB to further enhance the linearity and to accommodate very large blockers. Accordingly, the input P1dB is enhanced to +13.7 dBm while the noise figure is increased by 8.1 dB. A technique is also introduced to maintain the input matching when the LNA is switched to operate in the low-gain mode.