Publication type: Article in scientific journal
Type of review: Peer review (publication)
Title: Symmetrically biased T/R switches for NMR and MRI with microsecond dead time
Authors: Brunner, David O.
Furrer, Lukas
Weiger, Markus
Baumberger, Werner
Schmid, Thomas
Reber, Jonas
Dietrich, Benjamin E.
Wilm, Bertram J.
Froidevaux, Romain
Pruessmann, Klaas P.
DOI: 10.1016/j.jmr.2015.12.016
Published in: Journal of Magnetic Resonance
Volume(Issue): 263
Pages: 147
Pages to: 155
Issue Date: 2016
Publisher / Ed. Institution: Elsevier
ISSN: 1090-7807
Language: English
Subjects: Dead time reduction; Short; TR switching; Zero echo time imaging
Subject (DDC): 530: Physics
Abstract: For direct NMR detection and imaging of compounds with very short coherence life times the dead time between radio-frequency (RF) pulse and reception of the free induction decay (FID) is a major limiting factor. It is typically dominated by the transient and recovery times of currently available transmit-receive (T/R) switches and amplification chains. A novel PIN diode-based T/R switch topology is introduced allowing for fast switching by high bias transient currents but nevertheless producing a very low video leakage signal and insertion loss (0.5dB). The low transient spike level in conjunction with the high isolation (75dB) prevent saturation of the preamplifier entirely which consequently does not require time for recovery. Switching between transmission and reception is demonstrated within less than 1μs in bench tests as well as in acquisitions of FIDs and zero echo time (ZTE) images with bandwidths up to 500kHz at 7T. Thereby the 2kW switch exhibited a rise-time of 350ns (10-99%) producing however a total video leakage of below 20mV peak-to-peak and less than -89dBm in-band. The achieved switching time renders the RF pulse itself the dominant contribution to the dead time in which a coherence cannot be observed, thus making pulsed NMR experiments almost time-optimal even for compounds with very short signal life times.
Fulltext version: Published version
License (according to publishing contract): Licence according to publishing contract
Departement: School of Engineering
Organisational Unit: Institute for Signal Processing and Wireless Communications (ISC)
Appears in collections:Publikationen School of Engineering

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