Output stage of a current-steering multipolar and multisite deep brain stimulator

Clinical deep brain stimulation (DBS) is based on the use of cylindrical electrodes driven in monopolar or bipolar configurations. The simulation field spreads symmetrically around the electrode modulating both targeted and non-targeted neural structures. Recent advances have focused on novel stimulation techniques based on the use of high-density segmented electrodes, which allow current-steering and field-shaping capability. This paper presents the architecture of a multi-channel current-steering stimulator output stage that allows for monopolar, bipolar, tripolar and quadripolar multi-site stimulation. The core of the output stage comprises N independent high-compliance current drivers (HCCDs), capable of delivering up to 1.5 mA complementary currents in 10 different current ranges. Each of the N HCCDs can drive up to 8 adjacent electrode contacts thanks to a 2-32 multiplexer controlled by a 5-32 decoder. The HCCD was designed in a HV 0.18μm CMOS process. The circuits were simulated in Cadence Spectre and simulated results are presented in the paper.