Abstract: A gradient current speed-up circuit, for use in a higher-speed NMR imaging system with a gradient power amplifier and an associated gradient, coil, has a high-voltage power supply which is selectively connected to the associated gradient coil, typical via a plurality of semiconductor switching elements, to supply a pulse of a very high voltage when fast coil rise and fall times are needed. The gradient coil is connected between selected ones of semiconductors devices which are turned on and off in selected patterns, to cause the direction of coil current flow to be determined.