Low Noise Amplifiers Manufacturers

The low noise amplifier is a type of electronic amplifier or amplifier which is used in communication systems to amplify very weak signals captured by an antenna. It is also called an LNA or a preamplifier. It is often located very close to the antenna. If the LNA is located close to the antenna, then losses in the feedline become less critical. This active antenna arrangement is frequently used in microwave systems like GPS, because coaxial cable feedline is very lossy at microwave frequencies. For low noise the amplifier needs to have a high amplification in its first stage. Therefore JFETs and HEMT are used and distributed amplifiers could be used. They are driven in a high current regime, which is not energy efficient, but reduces the relative amount of shot noise. Input and output matching circuits for narrow band circuits enhance the gain and do not use resistors, as these will add noise. Biasing is done by large resistors, because energy efficiency is not needed, and a large resistor prevents leakage of the weak signal out of the signal path or noise into the signal path.