Performance and characterization of the SPT-3G digital frequency-domain multiplexed readout system using an improved noise and crosstalk model

• Main Authors: Montgomery, J., Ade, P.A.R., Ahmed, Z., Anderes, E., Anderson, A.J., Archipley, M., Avva, J.S., Aylor, K., Balkenhol, L., Barry, P.S., Basu Thakur, R., Benabed, K., Bender, A.N., Benson, B.A., Bianchini, F., Bleem, L.E., Bouchet, F.R., Bryant, L., Byrum, K., Carlstrom, J.E., Carter, F.W., Cecil, T.W., Chang, C.L., Chaubal, P., Chen, G., Cho, H.-M, Chou, T.-L, Cliche, J.-F, Crawford, T.M., Cukierman, A., Daley, C., De Haan, T., Denison, E.V., Dibert, K., Ding, J., Dobbs, M.A., Dutcher, D., Elleflot, T., Everett, W., Feng, C., Ferguson, K.R., Foster Bb, A., Fu, J., Galli, S., Gambrel, A.E., Gardner, R.W., Goeckner-Wald, N., Groh, J.C., Gualtieri, R., Guns, S.
• Other Authors: Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), SPT-3G
• Format: Report
• Language: English
• Published: HAL CCSD 2021
• Subjects: [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det]; [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]; South Pole; South pole
• Online Access: https://hal.archives-ouvertes.fr/hal-03197499

The third generation South Pole Telescope camera (SPT-3G) improves upon its predecessor (SPTpol) by an order of magnitude increase in detectors on the focal plane. The technology used to read out and control these detectors, digital frequency-domain multiplexing (DfMUX), is conceptually the same as used for SPTpol, but extended to accommodate more detectors. A nearly 5x expansion in the readout operating bandwidth has enabled the use of this large focal plane, and SPT-3G performance meets the forecasting targets relevant to its science objectives. However, the electrical dynamics of the higher-bandwidth readout differ from predictions based on models of the SPTpol system. To address this, we present an updated derivation for electrical crosstalk in higher-bandwidth DfMUX systems, and identify two previously uncharacterized contributions to readout noise. The updated crosstalk and noise models successfully describe the measured crosstalk and readout noise performance of SPT-3G, and suggest improvements to the readout system for future experiments using DfMUX, such as the LiteBIRD space telescope.