Measuring Noise Figure and Noise Power

One of the challenges in noise‐figure measurements is in determining the noise figure of systems that integrate the low‐noise amplifier (LNA) stage into a single‐chip down‐converter, where the output is not at the same frequency as the input and the LNA cannot be separated from the rest of the system. This chapter illuminates the details of noise figure and noise‐power measurements, including their uncertainty, verification, and methods to improve them. It discusses active antenna noise‐figure measurements and describes noise figure in mixers and frequency converters. Mixers and frequency converters are often the first component after the antenna in a receiver system, and as such the noise figure of the first converter predominantly sets the noise figure of the system. The chapter also discusses noise power measurements with a vector network analyzer spectrum analyzer and noise figure measurements using spectrum analysis as well as carrier‐to‐noise measurements.