title: A CMOS Current Steering Neurostimulation Array With Integrated DAC Calibration and Charge Balancing.
abstract: An 8-channel current steerable, multi-phasic neural stimulator with on-chip current DAC calibration and residue nulling for precise charge balancing is presented. Each channel consists of two sub-binary radix DACs followed by wide-swing, high output impedance current buffers providing time-multiplexed source and sink outputs for anodic and cathodic stimulation. A single integrator is shared among channels and serves to calibrate DAC coefficients and to closely match the anodic and cathodic stimulation phases. Following calibration, the differential non-linearity is within ±0.3 LSB at 8-bit resolution, and the two stimulation phases are matched within 0.3%. Individual control in digital programming of stimulation coefficients across the array allows altering the spatial profile of current stimulation for selection of stimulation targets by current steering. Combined with the self-calibration and current matching functions, the current steering capabilities integrated on-chip support use in fully implanted neural interfaces with autonomous operation for and adaptive stimulation under variations in electrode and tissue conditions. As a proof-of-concept we applied current steering stimulation through a multi-channel cuff electrode on the sciatic nerve of a rat.
authors.forename: Elliot
authors.initials: E
authors.lastname: Greenwald
authors.forename: Christoph
authors.initials: C
authors.lastname: Maier
authors.forename: Qihong
authors.initials: Q
authors.lastname: Wang
authors.forename: Robert
authors.initials: R
authors.lastname: Beaulieu
authors.forename: Ralph
authors.initials: R
authors.lastname: Etienne-Cummings
authors.forename: Gert
authors.initials: G
authors.lastname: Cauwenberghs
authors.forename: Nitish
authors.initials: N
authors.lastname: Thakor
mesh_terms: D000818:Animals; D002138:Calibration; D004558:Electric Stimulation; D004867:Equipment Design; D058542:Implantable Neurostimulators; D051381:Rats