An extremely low power and low voltage UWB-IR LNA for the 3–5GHz range is presented. Based on the bias optimization methodology, an extremely low drain bias (0.25-V) combined with an optimum gate voltage scheme is applied to a two-stage common-source amplifier. In addition, to overcome the increase in the circuit area occupation caused by the additional matching resonator in a cascaded structure, small 3-D inductors are adopted in our design. The UWB-IR LNA shows a peak gain of 13.3dB, more than 8dB of input/output return loss, and a noise figure of 3.5–4.0dB from 3 to 5GHz with a power dissipation of 1.77mW.