Characterizing performance of CMB-S4 superconducting readout electronics*

CMB-S4 is the next-generation ground-based cosmic microwave background survey, designed to probe the early universe and cosmic inflation. CMB-S4 will achieve its science goals in part by dramatically increasing the number of transition edge sensor (TES) bolometer detectors on the sky, which requires improvements to the detector readout system CMB-S4 will use: time-division multiplexing (TDM) with a two-stage Superconducting Quantum Interference Device (SQUID) system. To accommodate the large increase in detectors, the size of our camera increases, placing physical constraints on the readout, its wiring, and its power dissipation. Therefore, to optimize readout performance, we need to balance competing design considerations such as thermal load and bandwidth. We will show preliminary results characterizing components of this readout system and their impact on overall system performance.