Linearity of1fNoise Mechanisms

Measurements of statistical quantities other than the spectrum can distinguish between different $\frac{1}{f}$ noise mechanisms. One such quantity, the average behavior before and after a given fluctuation amplitude, is used to determine if the noise mechanism is linear. Measurements on different sources show that $\frac{1}{f}$ noise in some systems, such as carbon resistors and field-effect transistors, is due to a linear mechanism, while other systems, such as $p-n$ junction devices, require a nonlinear mechanism.