Flicker noise
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Flicker noise is a type of electronic noise with a 1/f, or pink spectrum. It is therefore often referred to as 1/f noise or pink noise, though these terms have wider definitions. It occurs in almost all electronic devices, and results from a variety of effects, such as impurities in a conductive channel, generation and recombination noise in a transistor due to base current, and so on. It is always related to a direct current.
In electronic devices, it is a low-frequency phenomenon, as the higher frequencies are overshadowed by white noise from other sources. Flicker noise is often characterized by the corner frequency between the regions dominated by each type, which is usually below 2 kHz.
Flicker noise is found in carbon composition resistors, where it is referred to as excess noise, since it increases the overall noise level above the thermal noise level, which is present in all resistors. In contrast, wire-wound resistors have the least amount of flicker noise. Since flicker noise is related to the level of DC, if the current is kept low, thermal noise will be the predominant effect in the resistor, and the type of resistor used will not affect noise levels.
