Binary search algorithms could be slightly improved

[DavidLP]

There is one special case where we could find a better value: Imagine:

• We are at the last iteration: TDAC = 1111 with Occ = N_inj: means threshold is still too low
• Then we do the additional last bit = 0 iteration: TDAC = 1110 with Occ = N_inj - 1. Here we measure just by statistical error one count less. Than this result is taken. But we know already that even TDAC = 1111 was still too low bad. This information could be used to prevent this.

Solution: Do not do / use the last iteration result when all preceding bits are set.

[laborleben]

Don't we have these issues with every scan step? The issue is more likely to appear for the LSB, but also the tuning error is the smallest for the LSB being wrong. I don't see how we can solve this and get significant better results.

A solution would be to increase the number of injections - this is equivalent to increased statistics.

[DavidLP]

Significant better results not, but a cross check that threashol(TDAC) is monotone could inprove the result.

[laborleben]

We store the best result in all tunings. Event if binary search does not give a good result we will overwrite with the optimal result afterwards.

E.g. 10000 -> first step ... 11100 -> this is optimal result, but a little bit too high 11010 -> this in 3nd optimal result, but too low 11011 -> this in 2nd optimal result, but a little too low 11010 -> repeating last scan step with 0 (see above) -> change to 11011 11100 -> replaced 11011 with 11100, because the latter was better