Journal
JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS
Volume 8, Issue 1, Pages -Publisher
SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS
DOI: 10.1117/1.JATIS.8.1.014001
Keywords
third-generation South Pole Telescope camera; digital frequency-domain multiplexing; frequency-domain multiplexing; readout noise; crosstalk; cosmic microwave background instrumentation
Funding
- National Science Foundation (NSF) [PLR-1248097, OPP-1852617]
- NSF Physics Frontier Center [PHY-1125897]
- Kavli Foundation
- Gordon and Betty Moore Foundation [947]
- U.S. Department of Energy, Office of High Energy Physics [DE-AC02-06CH11357]
- Argonne Center for Nanoscale Materials
- Natural Sciences and Engineering Research Council of Canada
- Canadian Institute for Advanced Research
- Fonds de recherche du Quebec Nature et technologies
- NSF CAREER grant [AST-0956135]
- [DE-AC02-07CH11359]
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The third-generation South Pole Telescope camera (SPT-3G) improves its predecessor by increasing the number of detectors on the focal plane. The use of digital frequency-domain multiplexing (DfMUX) technology allows for a larger focal plane. However, the electrical dynamics of the higher-bandwidth readout differ from predictions, and updated models are needed to address crosstalk and noise issues.
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 due to the higher frequencies used and parasitic impedances associated with new cryogenic electronic architecture. 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, which become dominant at high bias frequency. The updated crosstalk and noise models successfully describe the measured crosstalk and readout noise performance of SPT-3G. These results also suggest specific changes to warm electronics component values, wire-harness properties, and SQUID parameters, to improve the readout system for future experiments using DfMUX, such as the LiteBIRD spacete lescope. (C) 2022 Society of Photo-Optical Instrumentation Engineers (SPIE)
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