This document discusses the design of low-noise amplifiers. It begins with an overview of the basic structure of transmitters and receivers in wireless communication systems. It then reviews the relationships between power and gain and introduces the concept of the available power gain circle. The document discusses a design method for amplifiers that does not require simultaneous conjugate matching of both ports. It also covers noise theory for two-port networks and the fixed noise figure circle. The key points are utilizing available power gain circles and fixed noise figure circles to design amplifiers through tradeoffs between gain and noise on the Smith chart.