  We describe a cryogenic instrumentation platform incorporating
commercially-available field-programmable gate arrays (FPGAs) configured to
operate well beyond their specified temperature range. The instrument enables
signal routing, multiplexing, and complex digital signal processing at
temperatures approaching 4 kelvin and in close proximity to cooled devices or
detectors within the cryostat. The cryogenic performance of the system is
evaluated, including clock speed, error rates, and power consumption. Although
constructed for the purpose of controlling and reading out quantum computing
devices with low latency, the instrument is generic enough to be of broad use
in a range of cryogenic applications.
