A Linearity-Enhanced 18.7–36.5-GHz LNA With 1.5–2.1-dB NF for Radar Applications

This letter presents a
${K}$
-/
Ka
-band gallium arsenide (GaAs) low-noise amplifier (LNA) for high dynamic range (DR) radar systems. The proposed LNA adopts a two-stage topology to acquire a compact chip size and low power consumption. A feedback circuit is employed in the second stage to achieve a wideband gain response. A diode-based adaptive bias circuit is designed to simultaneously improve the linearity and maintain a low drain current. In the 3-dB bandwidth from 18.7 to 36.5 GHz, the LNA achieves a maximum small-signal gain of 15.9 dB and a minimum noise figure (NF) of 1.5 dB. The measured input 1-dB compression point (IP
_1dB
) is higher than −1 dBm, and the measured input-referred intercept point (IIP
₃
) is higher than 3.2 dBm in the operation band. The LNA has a chip size of 1.2 mm
$\times0.8$
mm and the power consumption is 66 mW.