SLAC Microresonator Radio Frequency (SMuRF) Electronics for Read Out of Frequency-Division-Multiplexed Cryogenic Sensors

S. A. Kernasovskiy, S. E. Kuenstner, E. Karpel, Z. Ahmed, D. D. Van Winkle, S. Smith, J. Dusatko, J. C. Frisch, S. Chaudhuri, H. M. Cho, B. J. Dober, S. W. Henderson, G. C. Hilton, J. Hubmayr, K. D. Irwin, C. L. Kuo, D. Li, J. A.B. Mates, M. Nasr, S. TantawiJ. Ullom, L. Vale, B. Young

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Large arrays of cryogenic sensors for various imaging applications ranging across x-ray, gamma-ray, cosmic microwave background, mm/sub-mm, as well as particle detection increasingly rely on superconducting microresonators for high multiplexing factors. These microresonators take the form of microwave SQUIDs that couple to transition-edge sensors or microwave kinetic inductance detectors. In principle, such arrays can be read out with vastly scalable software-defined radio using suitable FPGAs, ADCs and DACs. In this work, we share plans and show initial results for SLAC Microresonator Radio Frequency (SMuRF) electronics, a next-generation control and readout system for superconducting microresonators. SMuRF electronics are unique in their implementation of specialized algorithms for closed-loop tone tracking, which consists of fast feedback and feedforward to each resonator’s excitation parameters based on transmission measurements. Closed-loop tone tracking enables improved system linearity, a significant increase in sensor count per readout line, and the possibility of overcoupled resonator designs for enhanced dynamic range. Low-bandwidth prototype electronics were used to demonstrate closed-loop tone tracking on twelve 300-kHz-wide microwave SQUID resonators, spaced at ∼ 6 MHz with center frequencies ∼ 5–6 GHz. We achieve multi-kHz tracking bandwidth and demonstrate that the noise floor of the electronics is subdominant to the noise intrinsic in the multiplexer.

Original languageEnglish (US)
Pages (from-to)570-577
Number of pages8
JournalJournal of Low Temperature Physics
Issue number3-4
StatePublished - Nov 1 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • General Materials Science
  • Condensed Matter Physics


  • FPGA
  • Microresonators
  • Microwave SQUIDs
  • MKIDs
  • Multiplexing
  • TES
  • Tone-tracking


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