Spectral Density
Low frequency power fluctuations in electronic components follow a distribution inversely proportional to the frequency. Most semiconductors exhibit flicker noise below a specific corner frequency where the magnitude exceeds the thermal noise floor. This phenomenon appears as a slope in the power spectral density plot.
Physical Source
Carrier trapping at the interface between the semiconductor and the insulator creates these temporal variations. Surface defects in a resistor or transistor capture and release electrons at different rates. The flicker noise magnitude increases with the direct current flowing through the device.
Measurement Window
Long duration observations are necessary to quantify the amplitude of these signals accurately. Engineers use zero hertz to ten hertz bandwidths to capture the peak to peak voltage of the flicker noise contribution. Because the power increases at lower frequencies, the total noise depends on the total observation time.
This specific characteristic makes the noise difficult to remove through simple averaging techniques. Data recorded over several hours might show a slow drift caused by these physical fluctuations.
Mitigation Strategy
Chopper stabilization and large area transistors help reduce the impact on precision circuits. High quality materials with fewer crystal defects lower the noise coefficient. The flicker noise level is a primary differentiator for low power instrumentation amplifiers.
