e-journal

Nonlinear Signal-Specific ADC for Efficient Neural Recording in Brain-Machine Interfaces

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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.
Index Terms—A/D converters, brain-machine interfaces, implantable biomedical microsystems, nonlinear ADCs.

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Informasi Detail

Judul Seri

IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS

No. Panggil

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Penerbit

New York : IEEE., 2014

Deskripsi Fisik

IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, VOL. 8, NO. 3, JUNE 2014

Bahasa

English

ISBN/ISSN

1932-4545

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

VOL. 8, NO. 3, JUNE 2014

Subjek

TEKNIK

Info Detail Spesifik

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Pernyataan Tanggungjawab

Yuli/Agus

Versi lain/terkait

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