Electronic devices intrinsically have different types of noise sources including thermal (Johnson) noise, shot noise, white (broadband) noise, and 1/f (flicker) noise. 1/f noise is low-frequency electronic noise where the current (ISD) or power (PSD) spectral density is inversely proportional to the frequency. Many types of components exhibit 1/f noise including semiconductor devices, some types of resistors,
2D materials such as graphene, and even chemical cells.
This application note explains how to make 1/f noise measurements with the 4200A-SCS using both SMUs and the PMU. In particular, the following paragraphs describe 1/f noise basics, determining the noise floor of an instrument by deriving the current spectral density (ISD) on a particular range, measuring the drain current 1/f noise of a MOSFET, configuring 1/f noise measurements on two-terminal devices, and describes the built-in FFT functions.