Abstract ─This paper introduces a high flat gain broadband Low Noise Amplifier (LNA) design approach, which is based on using a new methodology of Real Frequency Technique (RFT). To get this done, the optimum matching network has been designed with second-order LC lumped elements to minimize the Noise Figure (NF) and maximize the Transducer Gain (GT) based on selecting the optimum (ZS, ZL) LNA terminations that have been used over a 2.1-4.2 GHz. The design has demonstrated a high stable gain in the range of 19.19 –18.73 dB with ± 0.2 dB gain flatness over the specified band. Moreover, the NF has been obtained at 0.68 – 0.82 dB and a stable operation throughout a broad bandwidth. Furthermore, the proposed method results have been compared with an analytical methodology which is based on computing equivalent input and output circuits for the transistor model using its scattering parameters. For the verification purpose, the performances of the synthesized amplifier are compared using MATLAB platform and ADS simulation software. The output results have a good agreement with the proposed method outcomes, which makes this method a new promising technique for the high flat gain broadband LNA design.