Microwave SQUID Multiplexer Readout Performance Using a Direct-RF RFSoC-Based Software-Defined Radio

Abstract: In this work, we report the experimental readout results of a {\mu}MUX device using a Direct-RF SDR prototype based on the ZCU216 Radio-Frequency System-on-Chip (RFSoC) evaluation board. First, the analog performance of the SDR system was evaluated both in loopback and coupled to the cryogenic multiplexing system. Then, the SDR system performance was optimized for {\mu}MUX readout, focusing on bolometric applications. Finally, the minimum demodulated flux noise was obtained through the optimally conditioned readout of a {\mu}MUX channel. The results presented are comparable to those obtained with traditional SDR architectures and demonstrate that the Direct-RF SDR prototype is suitable for the readout of {\mu}MUX devices. We anticipate that Direct-RF SDR technology will play a key role in enabling the next generation of SDR readout systems for frequency-multiplexed low-temperature detector arrays.