Abstract #0650

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

Thomas Grafendorfer^1,2, 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.