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Abstract #0650

Frequency Selective Negative Feedback to Avoid Preamplifier Oscillation in Multi-Channel Arrays

Thomas Grafendorfer1,2, Greig Scott2, Paul Calderon3, Fraser Robb4, Shreyas Vasanawala5

1RX & ATD Coils, GE Healthcare, Stanford, CA, United States; 2Electrical Engineering, Stanford University, Stanford, CA, United States; 3MR Hardware Engineering, GE Healthcare, Fremont, CA, United States; 4Advanced Technology, GEHC Coils, Aurora, OH, United States; 5Radiology, Stanford University, Stanford, CA, United States

Placing the preamplifiers close to the coil elements in multi-channel arrays increases preamplifier-decoupling performance, which leads to better SNR and better acceleration performance. Unfortunately it also opens a new feedback path that can easily lead to oscillation. We developed a new strategy by applying frequency selective negative feedback that suppresses the gain at the so-called match split peaks outside the frequency band relevant for MRI. This greatly reduces the possibility for oscillation, and the gain within the signal band stays more or less unaffected.