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The apparent step-function point at around 400 pulser value corresponds to gain switching point in injected pixels. Now the question is what causes this jump in non-injected pixels
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Measuring the effect of charge injection block position on the control pixel shows that the step point position (pulser value at which the jump occurs) changes, as well as the baseline after the step. In this measurement the injected columns were 14 - 86, 86 - 158, 158 - 230, 230 - 302 and 302 - 374 (72 columns per injection step), while monitoring the same pixel 103,4.
Here is a plot of the first and last extremes for clarity (colors do not correspond to the plot above)
So, not only the amount of charge affects the baseline (non-injected pixel), but the position of the charge on the asic relative to the control pixel.
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