Practical Considerations for Low Noise Amplifier Design

Low noise amplifiers (LNAs) play a key role in radio receiver performance. The success of a receiver’s design is measured in multiple dimensions: receiver sensitivity, selectivity, and proclivity to reception errors. The RF design engineer works to optimize receiver front−end performance with a special focus on the first active device.

This paper considers device− and board−level variables that affect LNA performance and confront the engineer at each level of design in accommodating the various requirements of specific applications. To illustrate the practical challenges, performance trade−offs for three popular LNA topologies and two process technology implementations are examined. Each of the topics covered can easily be expanded into individual chapters, but the purpose of this paper is to provide a concise summary of the most salient considerations affecting LNA performance and implementation.