Designing a Transmitter and Receiver for Use in Strong Magnetic Fields
Kripiakevitch D, Kolansky G, Hoult D
National Research Council Canada
The advantages of a transmitter and receiver operating close to the MR magnet are outlined, and the importance for the Cartesian feedback method of phased-array transmission emphasised. Attention is drawn to the ubiquitous conventional use of ferrites that precludes high magnetic field operation, and the use of new, balanced, radio-frequency integrated circuits, together with toroidal inductors, is advocated for eliminating ferrites. Examples of new designs include a 20 MHz I-Q modulator with 60 dB rejection of carrier and unwanted sideband, a quadrature splitter with 0.5o phase accuracy between 300 and 500 MHz and a 150 W ferrite-free RF amplifier.