This research presents a Low Noise Amplifier (LNA) design, operating between the L & S bands of the RF spectrum (1-2GHz & 2-4GHz respectively) using heterojunction materials. A comparison between Silicon (Si) and Gallium Arsenide (GaAs) is presented that covers
electron mobility and thermal noise, as well as a programmable level detector circuit to avoid external interference in Si. Migration from Si to GaAs is presented. Circuit simulations are illustrated with design parameter results.