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A CMOS Current Steering Neurostimulation Array With Integrated DAC Calibration and Charge Balancing.

Authors
  • Greenwald, Elliot
  • Maier, Christoph
  • Wang, Qihong
  • Beaulieu, Robert
  • Etienne-Cummings, Ralph
  • Cauwenberghs, Gert
  • Thakor, Nitish
Type
Published Article
Journal
IEEE Transactions on Biomedical Circuits and Systems
Publisher
Institute of Electrical and Electronics Engineers
Publication Date
Apr 01, 2017
Volume
11
Issue
2
Pages
324–335
Identifiers
DOI: 10.1109/TBCAS.2016.2609854
PMID: 28092575
Source
Medline
License
Unknown

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.

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