Architectures for Multi-Electrode Implantable Stimulator Devices Having Minimal Numbers of Decoupling Capacitors

Abstract

Architectures for implantable stimulators having N electrodes are disclosed. The architectures contains X current sources, or DACs. In a single anode/multiple cathode design, one of the electrodes is designated as the anode, and up to X of the electrodes can be designated as cathodes and independently controlled by one of the X DACs, allowing complex patient therapy and current steering between electrodes. The design uses at least X decoupling capacitors: X capacitors in the X cathode paths, or one in the anode path and X−1 in the X cathode paths. In a multiple anode/multiple cathode design having X DACs, a total of X−1 decoupling capacitors are needed. Because the number of DACs X can typically be much less than the total number of electrodes (N), these architectures minimize the number of decoupling capacitors which saves space, and ensures no DC current injection even during current steering.

What is claimed is: 
     
         1 . An implantable medical device, comprising:
 a plurality of N electrodes, wherein only one first of the electrodes is designated as either a cathode or an anode having a first current path, and wherein a second plurality of the other of the electrodes are designatable as the other of cathodes or anodes each having a second current path;   a plurality of X current sources, each current source being coupleable to one of the second electrodes, wherein X is less than N; and   a plurality of at least X capacitors, wherein the at least X capacitors are placed in the first or second current paths.