Gradient speed-up circuit for NMR system
First Claim
Patent Images
1. A gradient speed-up circuit, for use in a high-speed NMR imaging system, comprising:
- a gradient power amplifier means for creating an output signal which is linearly related to a received control signal for controlling a current flowing through an output circuit;
a gradient coil having at least one portion series connected to said amplifier output circuit;
a high voltage power supply being series coupled to the gradient power amplifier means and gradient coil; and
a power switching means being a full-bridge circuit for connecting the high voltage power supply in series with the gradient power amplifier means and the gradient coil, causing a current flow from the high voltage power supply through the gradient power amplifier means, and the gradient coil to change the gradient coil current, the power switching means being responsive to control signals.
1 Assignment
0 Petitions
Accused Products
Abstract
A gradient current speed-up circuit, for use in a higher-speed NMR imaging system having an associated gradient coil, has a gradient power amplifier receiving an input analog signal controlling the current in an amplifier output circuit connected in series between first and second portions of a single gradient coil. Semiconductor switching elements selectively connect the coil portion-amplifier-coil portion between first and second potential sources, and are turned on and off in selected patterns to cause a current to be suddenly applied to, and removed from, flow through the associated gradient coil and the amplifier output circuit.
19 Citations
17 Claims
-
1. A gradient speed-up circuit, for use in a high-speed NMR imaging system, comprising:
-
a gradient power amplifier means for creating an output signal which is linearly related to a received control signal for controlling a current flowing through an output circuit; a gradient coil having at least one portion series connected to said amplifier output circuit; a high voltage power supply being series coupled to the gradient power amplifier means and gradient coil; and a power switching means being a full-bridge circuit for connecting the high voltage power supply in series with the gradient power amplifier means and the gradient coil, causing a current flow from the high voltage power supply through the gradient power amplifier means, and the gradient coil to change the gradient coil current, the power switching means being responsive to control signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
8. A gradient speed-up circuit, for use in a high-speed NMR imaging system, comprising:
-
gradient power amplifier means for controlling a current flowing through an output circuit, responsive to an input signal; a gradient coil having separate first and second portions, each series connected to an opposite end of said amplifier output circuit, said amplifier means adapted to cause a shim current to flow through both portions of said gradient coil; and power switching means for providing a current flow through the series circuit of said amplifier means and coil portions to change the coil current responsive to control signals.
-
-
9. A gradient speed-up circuit, for use in a high-speed NMR imaging system, comprising:
-
gradient power amplifier means for controlling a current flowing through an output circuit, responsive to an input signal, the power amplifier means including a pair of amplifiers each having a separate output circuit, and a shield winding connected between the output circuits of the amplifiers; a gradient coil having separate first and second portions, each series connected to an opposite end of said amplifier output circuit such that an amplifier-shield winding-amplifier subcircuit is connected between the coil first and second portions; and power switching means for providing a current flow through the series circuit of said amplifier and coil portions to change the coil current responsive to control signals.
-
Specification