Tunnel-diode Amplifier

A tunnel-diode amplifier is a form of low-noise amplifier (LNA) used in satellite communications transponders to amplify very weak RF uplink signals. It exploits the negative-resistance characteristic of a tunnel diode to achieve low noise figures at microwave frequencies, making it well suited to early satellite receiver front ends. While largely superseded in modern systems by GaAs and GaN field-effect transistor LNAs, tunnel-diode amplifiers were widely used in early satellite communications because of their excellent noise performance and inherent reliability.