| 摘要 |
A current management system for use in the stimulation output stage of a neurostimulation system can be programmed to steer different amounts of current through different stimulation electrodes to vary how strongly the tissue adjacent each electrode is stimulated during a particular programmed stimulation episode. An stimulation electrode drive circuit associated with each electrode that is available for stimulation allows independent control of the flow of current through that electrode. A reference electrode is provided in the circuit to source or sink current as necessary to balance the currents going into and out of the patient, so that no stimulation electrode is required to serve that purpose. More specifically, by configuring the circuit to maintain a constant potential at the reference electrode (e.g., a potential that is approximately half way between a top and bottom voltage rail), the reference electrode will source or sink currents as necessary to cause the net current flow into the patient to be equal to the net current flowing out of the patient, thus satisfying Kirchhoff's current law. |
| 主权项 |
1. A current management system for a stimulation output stage of a neurostimulation system enclosed in a housing having an electrically conductive surface, the neurostimulation system including a plurality of stimulation electrodes, the current management system comprising:
a stimulation electrode drive circuit for each of the plurality of stimulation electrodes, each stimulation electrode drive circuit configured to receive a digital output and an analog output, and to: 1) in response to receipt of a first digital output and a first analog output, source current through its associated stimulation electrode in accordance with the limits of top and bottom voltage rails for a first period of time determined by the first digital output and at a reference current having an amplitude determined by the first analog output, 2) in response to receipt of a second digital output and a second analog output, sink current through its associated stimulation electrode in accordance with the limits of top and bottom voltage rails for a second period of time determined by the second digital output and at a reference current having an amplitude determined by the second analog output, 3) in response to receipt of a third digital output, cause its associated stimulation electrode to have a high impedance for a third period of time determined by the third digital output, and 4) in response to receipt of a fourth digital output, short its associated stimulation electrode for a fourth period of time determined by the fourth digital output; and a reference electrode drive circuit adapted to maintain the electrically conductive surface of the housing at a constant potential when any or all of the stimulation electrodes are sourcing or sinking current, so that the reference electrode will sink or source an amount of current equal to the total amount of current being sourced or sunk through the stimulation electrodes at any given time in a stimulation episode. |
