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

Elliot Greenwald, Christoph Maier, Qihong Wang, Robert Beaulieu, Ralph Etienne-Cummings, Gert Cauwenberghs, Nitish Thakor

Research output: Contribution to journalArticlepeer-review

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 \pm 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.

Original languageEnglish (US)
Article number7815268
Pages (from-to)324-335
Number of pages12
JournalIEEE Transactions on Biomedical Circuits and Systems
Volume11
Issue number2
DOIs
StatePublished - Apr 2017

Keywords

  • Charge balancing
  • current steering DAC calibration
  • electrical stimulation
  • field steering
  • neuromodulation
  • neurostimulator
  • sub-binary radix

ASJC Scopus subject areas

  • Biomedical Engineering
  • Electrical and Electronic Engineering

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