Serial powering scheme and performance analysis for the innermost layer (L0) of ATLAS ITk modules

In this study, we powered in series 4 triplets based on the pre-production ATLAS FE chip for HL-LHC. We ensured that the chosen operational parameters were within our theoretical specs and resulted in the stable operation of the modules within the serial power chain. Triplets were also powered in Low Power mode (LP), used to operate the module at a lower current, and their performance was tested without cooling requirements. The performance of the under-shunt and over-voltage protection were also analyzed.