Results and Limits of Time Division Multiplexing for the BICEP Array High Frequency Receivers

Abstract Time-Division Multiplexing is the readout architecture of choice for many groundand space experiments, as it is a very mature technology with proven outstandinglow-frequency noise stability, which represents a central challenge in multiplex-ing. Once fully populated, each of the two BICEP Array high frequency receivers,observing at 150GHz and 220/270GHz, will have 7776 TES detectors tiled on thefocal plane. The constraints set by these two receivers required a redesign of thewarm readout electronics. The new version of the standard Multi Channel Elec-tronics, developed and built at the University of British Columbia, is presentedhere for the first time. BICEP Array operates Time Division Multiplexing readouttechnology to the limits of its capabilities in terms of multiplexing rate, noise andcrosstalk, and applies them in rigorously demanding scientific application requir-ing extreme noise performance and systematic error control. Future experimentslike CMB-S4 plan to use TES bolometers with Time Division/SQUID-basedreadout for an even larger number of detectors.