Marta Gaia Zanchi1, Pascal Stang1,
John Mark Pauly1, Greig Cameron Scott1
1Electrical Engineering,
We
present a method and system based on Frequency Offset Cartesian feedback
(FOCF) to electronically manipulate the output impedance of the RF power
amplifiers for MRI transmitter arrays. In comparison to other methods, the
output impedance synthesized by FOCF can have any value within a large area
of the Smith chart, is stable over the power range, and does not hamper the
amplifier efficiency. Through simulations and measurements, we demonstrate
the ability to predictably manipulate the output impedance of a power
amplifier near 64 MHz from very low to very high values.
Keywords