A low noise amplifier, a LNA, is an important circuit in many types of RF and wireless systems. It is usually the first circuit to be encountered in an amplifier chain that starts at the output of the antenna. The FRIS formula shows that in a chain of amplifiers, the gain and noise of the first amplifier sets the noise of the entire chain. These amplifiers have a number of specifications that are used in the industry. A white paper published by Signal Processing Group Inc., describes these specifications and  provides their descriptions. Familiarity with these specifications can only result in better designs. Please access this paper from the SPG website. Use the “Complementary” link .