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Abstract #1465

Tuning the Output Impedance of RF Power Amplifiers with Frequency-Offset Cartesian Feedback

Marta Gaia Zanchi1, Pascal Stang1, John Mark Pauly1, Greig Cameron Scott1

1Electrical Engineering, Stanford University, Stanford, CA, United States

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.