Wide-band two-stage GaAs LNA for radio astronomy

Abstract

This paper presents the design, simulation and measurements of wideband two-stage LNAs using commercially available discrete components and targeting Square Kilometre Array (SKA) focalplane-array verification studies. The design optimization was implemented through simulations based on theoretical work that shows that low wide-band noise figures and power match are achievable by inner-stage component selection and device bias. In contrast to the conventional practice of having each stage of a discrete LNA matched to 50Ω, the inner stage was designed with a mismatching capacitor between the two stages. The measured results are presented for 0.7-1.4GHz and achieve noise figures below 0.4 dB, gain of at least 28 dB, mid-band input return loss of 7 dB, output P1 dB of 18.3 dBm, input-referred IP3 of −15.47 dBm, and power consumption of 500mW with a supply voltage of 5V.