LAUSR

A 2–18 GHz ultra wideband low noise amplifier (LNA) is illustrated in this letter. The proposed LNA adopts a two‐stage structure, which is composed of a common source amplifying stage and a cascode amplifying stage. By combining band extension matching technique, current reused topology and active bias circuit, the LNA performs excellent in gain, noise figure, power consumption, and immunization against the fluctuation of voltage supply. The LNA is implemented with a 0.18‐μm GaAs pseudomorphic high electron mobility transistor process and has a compact chip area of 1.75 × 1 mm2. The dedicated LNA achieves a measured average gain of 20.7 dB with ±1.5 dB variation all over the ultra‐wide bandwidth of 2–18 GHz. It also has a measured noise figure of lower than 1.7 dB and a measured output 1 dB compression point of higher than 5 dBm in the operating frequency band. The LNA has a low direct current power dissipation of 100 mW under a 5 V voltage supply.