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Proceedings Paper

Improved performance of TES bolometers using digital feedback
Author(s): Tijmen de Haan; Graeme Smecher; Matt Dobbs
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Paper Abstract

Voltage biased, frequency multiplexed TES bolometers have become a widespread tool in mm-wave astrophysics. However, parasitic impedance and dynamic range issues can limit stability, performance, and multiplexing factors. Here, we present novel methods of overcoming these challenges, achieved through digital feedback, implemented on a Field-Programmable Gate Array (FPGA). In the first method, known as Digital Active Nulling (DAN), the current sensor (e.g. SQUID) is nulled in a separate digital feedback loop for each bolometer frequency. This nulling removes the dynamic range limitation on the current sensor, increases its linearity, and reduces its effective input impedance. Additionally, DAN removes constraints on wiring lengths and maximum multiplexing frequency. DAN has been fully implemented and tested. Integration for current experiments, including the South Pole Telescope, will be discussed. We also present a digital mechanism for strongly increasing stability in the presence of large series impedances, known as Digitally Enhanced Voltage Bias (DEVB).

Paper Details

Date Published: 27 September 2012
PDF: 10 pages
Proc. SPIE 8452, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VI, 84520E (27 September 2012); doi: 10.1117/12.925658
Show Author Affiliations
Tijmen de Haan, McGill Univ. (Canada)
Graeme Smecher, McGill Univ. (Canada)
Three-Speed Logic, Inc. (Canada)
Matt Dobbs, McGill Univ. (Canada)

Published in SPIE Proceedings Vol. 8452:
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VI
Wayne S. Holland, Editor(s)

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