stefan.ballmer@LIGO.ORG - posted 14:58, Saturday 09 March 2024 - last comment - 14:42, Monday 11 March 2024(76228)
DCPA Anti-TIA (Anti-Transimpedance Amplifier Filters) show small missmatch
Meashured the transfer function between DCPD_A and DCPD_B usinng a broadband injection. There is a slight frequency-dependent disagreement (0.2dB) between the two diodes, right around 25Hz, where the TIA has its complex poles.
It looks like one or both Anti-TIA filters are slightly mismateched. We won't tweak it today because we don't know with one is the culprit.
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this looks to be related to the TIA response drift reported in LHO:75986.
The template used for this measurement can be found here:
/ligo/home/controls/sballmer/20240311/AoverBmeasurement.xml
Note: the max peak-peak deviation between DCPD_A and DCPD_B is 2.5%.
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