In this paper, an ultra-low-power and low-noise amplifier is presented for 90-nm CMOS RF frontends. By employing current-reused, and forward-body-bias techniques, a low-noise amplifier (LNA) can operate at a reduced supply voltage with micro-watt dc power consumption while maintaining reasonable gain performance at millimeter-wave frequencies. To reduce noise factor and bias current simultaneously, transformer feedback technique is selected to make compromise between noise figure and input matching. From the measurement results, the LNA exhibits a gain of 10.6 dB and noise figure of 5.4 dB at 40.2 GHz. Operated at a supply voltage of L.0 V, the dc power consumption of the LNA is 917 μW.