IEEE Transactions on Biomedical Circuits and Systems, Volume (8), No (3), Year (2014-6) , Pages (371-381)

Title : ( Nonlinear Signal-Specific ADC for Efficient Neural Recording in Brain-Machine Interfaces )

Authors: Mohsen Judy , Amir M. Sodagar , Reza Lotfi , Mohamad Sawan ,

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Abstract

A nonlinear ADC dedicated to the digitization of neural signals in implantable brain-machine interfaces is presented. Benefitting from an exponential quantization function, effective resolution of the proposed ADC in the digitization of action potentials is almost 2 bits more than its physical number of bits. Hence, it is shown in this paper that the choice of a proper nonlinear quantization function helps reduce the outgoing bit rate carrying the recorded neural data. Another major benefit of digitizing neural signals using the proposed signal-specific ADC is the considerable reduction in the background noise of the neural signal. The 8-b exponential ADC reported in this paper digitizes large action potentials with maximum resolution of 10.5 bits,while quantizing the small background noise is performed with a resolution of as low as 3 bits. Fully-integrated version of the circuit was designed and fabricated in a 0.18- m CMOS process,occupying 0.036 mm silicon area. Designed based on a two-step successive-approximation register ADC architecture, the proposed ADC employs a piecewise-linear approximation of the target exponential function for quantization. Operating at a sampling frequency of 25 kS/s (typical for intra-cortical neural recording)and with a supply voltage of 1.8 V, the entire chip, including the ADC and reference circuits, dissipates 87.2 W. According to the experiments, Noise-Content-Reduction Ratio (NCRR) of the ADC is 41.1 dB

Keywords

, A/D converters, brain-machine interfaces, implantable biomedical microsystems, nonlinear ADCs.
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@article{paperid:1045359,
author = {Mohsen Judy and Amir M. Sodagar and Lotfi, Reza and Mohamad Sawan},
title = {Nonlinear Signal-Specific ADC for Efficient Neural Recording in Brain-Machine Interfaces},
journal = {IEEE Transactions on Biomedical Circuits and Systems},
year = {2014},
volume = {8},
number = {3},
month = {June},
issn = {1932-4545},
pages = {371--381},
numpages = {10},
keywords = {A/D converters; brain-machine interfaces; implantable biomedical microsystems; nonlinear ADCs.},
}

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%0 Journal Article
%T Nonlinear Signal-Specific ADC for Efficient Neural Recording in Brain-Machine Interfaces
%A Mohsen Judy
%A Amir M. Sodagar
%A Lotfi, Reza
%A Mohamad Sawan
%J IEEE Transactions on Biomedical Circuits and Systems
%@ 1932-4545
%D 2014

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