s-curve bias

Depends on what you are talking about.

In analog electronics, an S-curve is the product of at least two unequal but counteracting physical influences, organized to make use of the relatively flat portion that can result, where one influence may cancel out or temporarily reverse the influence the other.

It has the characteristic of potentially having a constant value at three positions over a range of corresponding linear variables, and an average value that has a fair tolerance over and slightly outside of that range. This is a much larger range than could be maintained if a a straight counteraction were attempted.

In some cases the intentionally reversing slope between the two extreme calibration points can serve a distinct purpose in discriminators.

RL