Measurement and Analysis of Input-Signal Dependent Flicker Noise Modulation in Chopper Stabilized Instrumentation Amplifier

This letter presents measurement results and an analysis of an input-signal dependent flicker noise modulation in chopper stabilized current balancing instrumentation amplifier. Although the chopping is well known and often used for its effectiveness in flicker noise mitigation, measurement results show an increased effect of the 1/f noise proportional to input signal amplitude. This effect is often ignored in most publications and will also not be apparent in traditional noise measurements (due to the lack of input signal when doing noise measurements). The unexpected operation was confirmed by a Spectre simulation and the main cause can be attributed to a flicker noise modulation by input signals of large amplitude. Because of the signal-dependency of the effect, flicker noise remains (and can be significant) even when chopping is applied.