Design of two stage low noise amplifier using double stub matching network

This paper studies the design of two stage microwave low noise amplifier (LNA) for coastal radar application at S-band operation. The cascade amplifier configuration and double stub matching networks are applied in this design which is aimed to obtain high gain with minimum reflected RF power. The first stage uses E-pHEMT GaAs FET of ATF-551M4 type and the second one uses RF transistor of BFP740FESD type as an active device, respectively. The duroid substrate of 5880 type as a stub of microstrip line is deployed to achieve matching impedance network. This work uses the Agilent Design System (ADS) software to optimize the performance of LNA circuit design. The derived LNA characteristic at frequency 3 GHz are Gain = 30.87 dB, Noise Figure (NF) = 1.18 dB, VSWR input = 1.05 and VSWR output = 1.18, respectively.