Stephen J. Dodd1, George C. Nascimento1, Meng-Chi Hsieh2, Hellmut Merkle1, Joseph Murphy-Boesch1, Jyh-Horng Chen2, Alan P. Koretsky1, Afonso C. Silva1
1Laboratory of Functional and Molecular Imaging, NINDS, National Institutes of Health, Bethesda, MD, USA; 2Dept of Elec. Eng., National Taiwan University, Taipei, Taiwan
We are currently developing the building blocks for coil development for very high field 7T and 11.T animal and human MRI systems. Here we report the development of low-impedance, low noise preamplifiers for both field strengths and application of this technology to a high-field phased array for imaging of small animals at 500 MHz. Two FETs are used in the cascode configuration instead of an FET-bipolar combination, allowing the preamplifier to operate with lower supply voltage but retaining low-noise and high dynamic range. A four-element array for animal studies at 11.7T is presented to demonstrate their performance.
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