Development of TRL5 Firmware for Tuning, Biasing, and Readout of Kilopixel TES Bolometer Arrays

TL;DR

This paper presents the development of TRL5 firmware for digital frequency-domain multiplexing in space-based mm-wave telescopes, enabling scalable detector readout with improved efficiency and radiation mitigation.

Contribution

It introduces tailored FPGA firmware for LiteBIRD's bolometer arrays, enhancing power efficiency, radiation resilience, and supporting new biasing schemes for large-scale detector arrays.

Findings

Firmware successfully synthesizes bias tones and demodulates data.

Improvements in power and resource efficiency achieved.

Radiation-mitigation functions integrated.

Abstract

The next generation of space-based mm-wave telescopes, such as JAXA's LiteBIRD mission, require focal planes with thousands of detectors in order to achieve their science goals. Digital frequency-domain multiplexing (dfmux) techniques allow detector counts to scale without a linear growth in wire harnessing, sub-Kelvin refrigerator loads, and other scaling problems. In this paper, we describe the Digital Signal Processing (DSP) firmware executed in the design's FPGA. This firmware is responsible for synthesizing bias tones, performing dynamic feedback control of the bolometer voltage bias and/or Superconducting Quantum Interference Device (SQUID) nuller currents, demodulating and decimating bolometer channels into science data, and streaming the results for storage and eventual downlink. We describe how this firmware has been tailored for LiteBIRD, including the control path, improvements to power- and resource-efficiency, the addition of radiation-mitigation functions, and the integration of new bolometer biasing schemes that may help mitigate mission-specific design challenges. This paper is a companion piece to the description of the electronics platform in which the firmware operates.