Christoph Michael Schildknecht1, Markus Weiger1, Romain Froidevaux1, and Klaas Paul Pruessmann1
1Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zürich, Switzerland
1Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zürich, Switzerland
For short-T2 MRI
measurements, fast T/R switches that can handle high RF power are of paramount
importance. In this work, we present a T/R switch based on GaN MOSFETs that
switches in tens of nanoseconds and can handle a peak power of more than 1000W.
Topology of the
proposed GaN T/R switch. The impedance transformation is shown with lumped
elements but could also be done by distributed elements or transmission lines.
The control of the gate voltage can be as simple as a resistor between a
digital logic output and the MOSFET gate but can be extended to arbitrary waves
to smooth transient voltages in the RF circuitry.
Pictures
of the implementet T/R switch with a few key parts marked. As can be seen, most
of the board space is occupied by RF circuitry.
