Advanced RFSoC readout for space-based superconducting sensor arrays

Abstract

Low-energy threshold, high-resolution superconducting detector arrays with 103–105 pixels are increasingly necessary in ground- and space-based telescopes across the electromagnetic spectrum including mm-wave, far-infrared (Far-IR), near-infrared, X-ray, and gamma rays. Reading out such large numbers of sensors poses significant technical challenges, but recent cryogenic readout technology developments are enabling the simultaneous read out of significantly more channels with minimal performance impact. An especially promising set of cold readout technologies couple cryogenic sensors to superconducting resonators. These technologies rely on high-frequency RF electronics to interrogate and demodulate the sensors’ signals using digitally generated tones. Recently released Radio Frequency Systems-on-Chip (RFSoC) devices from Xilinx combine a FPGA with high-speed ADCs and DACs onto a single chip. These systems provide significant advantages for these applications, including lower cost, reduced size and weight, lower power consumption, and improved RF performance. While an RFSoC-based warm readout system would be attractive for a broad range of spacecraft applications, Xilinx has not announced plans for a space qualified version of its RFSoC devices and insufficient data is publicly available to evaluate the feasibility of using RFSoC devices in space. To evaluate the suitability of RFSoC devices for spacecraft applications, we have designed and built custom boards using all space-qualified components except for the RFSoC. In this contribution we present the design of our custom RFSoC board, measurements of critical aspects of board performance which relate to operation in the harsh space environment, and measurements of integrated RF performance targeting the readout of large superconducting sensor arrays and space-based radio spectrometry. In addition to a wide range of spacecraft applications including communications and radar, our RFSoC platform is a potentially critically enabling technology for missions prioritized by the recent 2020 Decadal Survey on Astronomy and Astrophysics including flagship Far-IR and X-ray missions, as well as Far-IR, X-ray, and Cosmic Microwave Background (CMB) probes.