Implantable CMOS front-end for nerve-signal sensors

Jannik Hammel Nielsen; Erik Bruun

doi:10.1117/12.582133

16 February 2005 Implantable CMOS front-end for nerve-signal sensors

Jannik Hammel Nielsen, Erik Bruun

Proceedings Volume 5651, Biomedical Applications of Micro- and Nanoengineering II; (2005) https://doi.org/10.1117/12.582133
Event: Smart Materials, Nano-, and Micro-Smart Systems, 2004, Sydney, Australia

Abstract

An implantable analog front-end for human nerve signal sensors is presented. The front-end is composed of a low-noise, high-gain pre-amplifier and an analog-to-digital converter (ADC) for quantizing the recorded nerve signal. The front-end is implemented in a 0.35um CMOS technology. The circuit draws 196uA from a 1.8V supply, thus consuming approximately 350uW excluding bias circuitry and buffers. As the signal provided by the nerve signal only has a magnitude of a few microvolts, the pre-amplifier intrinsic noise has to be minimized in order to retain a sufficient signal-to-noise ratio (SNR). A two-stage design for achieving an overall gain of 74dB is employed. For low thermal noise, the first stage is biased at a relatively high current and employs MOS transistors (MOSTs) biased in the weak inversion region. The chopper modulation technique is utilized for shifting low frequency 1/f-noise out of the signal band leaving thermal noise dominant in-band. The measured noise is approximately 7nV/sqrt(Hz) input referred, for a chopping frequency of 20kHz, while the measured gain is 72.5dB over a 4kHz bandwidth. The measured power supply rejection ratio (PSRR) is above 90dB and the common-mode rejection ratio (CMRR) exceeds 105dB inband. The implemented ADC is of the sigma-delta type, and uses a third order continuous-time loop-filter. The loop-filter is implemented using Gm-C integrators, and uses CMOS only for the transconductor implementation. The measured resolution of the manufactured ADC is 10 bits and features a dynamic range (DR) of 67dB at a sampling rate of 1.4MHz.

Citation Download Citation

Jannik Hammel Nielsen and Erik Bruun "Implantable CMOS front-end for nerve-signal sensors", Proc. SPIE 5651, Biomedical Applications of Micro- and Nanoengineering II, (16 February 2005); https://doi.org/10.1117/12.582133

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
12 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Amplifiers

Nerve

Signal to noise ratio

Modulation

Sensors

Interference (communication)

Transistors

Show All Keywords

Keywords/Phrases

Search In:

Publication Years