GE OPTIMA MR360 Service Training page 137

XFA is an IGBT-based switching amplifier. It provides a voltage to overcome the inductance
and resistance of the MR gradient coil. The XFD-PS powers the three XFAs.
Actually, the ideal output of XFA is a square wave. In order to decrease the time of rising
edge, XFA will output DC 1400V energized on the G-coil. After getting the top of square wave,
only 200V can sustain. The control board output the gate control signal to switch on or off
the IGBT to implement this function.
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