Today Koji came to the lab to help me out with the FSS and give me few tips.
We made some changes to the boost stage at U7 in North FSS Box board D040105-C.
All the changes were made by Koji personally. He replaced Koji showed me how to solder wires and SMD components so that I can do it better next time. We soldered the wires for the boost switch, replaced the resistor R29 with a thin film 5.6 kOhm resistor and replaced the capacitor (however the older capacitor was fine too). Overall, we made the arrangement of the components neater in the stage.
We figured that the only way to measure the transfer function of this stage when boost is on is to provide some reasonable offset as well so that the opamp doesn't saturate at DC. Hence, I do not have a good measurement of the stage before the changes were made. But after the touch-up, the stage is very close to the expectation as shown in the plot.
Relevant elog posts:
CTN:2384 : Mentioned that something is wrong with the boost stage. But It was just the issue of measuring it wrong.