Characterizing Prototype Components for Next-Generation Time-Division Multiplexing Readout of TES Detectors*

Applications with increasingly large arrays of superconducting transition edge sensors (TES) are driving the need for increasingly scalable cryogenic readout technologies. Time-division multiplexing (TDM) with a two-stage Superconducting Quantum Interference Device (SQUID) readout is a well-understood technology used for reading out focal plane arrays in astronomy. This includes TES bolometers for cosmic microwave background cosmology, which need highly linear, low-noise detector readout for precision measurements, and TES calorimeters for x-ray astronomy, which requires high speed readout of x-ray photons.  As focal planes continue to grow in size to increase sensitivity and field of view, tighter constraints are introduced on the detector readout system, including physical size, wiring density, and power dissipation. Optimizing system performance requires balancing competing considerations such as thermal load and bandwidth. We present results characterizing the thermal and electrical performance of prototype components designed for CMB-S4, including wiring and SQUID series array amplifiers. We discuss how these results inform the design of next-generation TES readout architectures with higher multiplexing factors.