DocumentCode :
940474
Title :
An Energy-Efficient Micropower Neural Recording Amplifier
Author :
Wattanapanitch, W. ; Fee, M. ; Sarpeshkar, R.
Author_Institution :
Massachusetts Inst. of Technol., Cambridge
Volume :
1
Issue :
2
fYear :
2007
fDate :
6/1/2007 12:00:00 AM
Firstpage :
136
Lastpage :
147
Abstract :
This paper describes an ultralow-power neural recording amplifier. The amplifier appears to be the lowest power and most energy-efficient neural recording amplifier reported to date. We describe low-noise design techniques that help the neural amplifier achieve input-referred noise that is near the theoretical limit of any amplifier using a differential pair as an input stage. Since neural amplifiers must include differential input pairs in practice to allow robust rejection of common-mode and power supply noise, our design appears to be near the optimum allowed by theory. The bandwidth of the amplifier can be adjusted for recording either neural spikes or local field potentials (LFPs). When configured for recording neural spikes, the amplifier yielded a midband gain of 40.8 dB and a -3-dB bandwidth from 45 Hz to 5.32 kHz; the amplifier´s input-referred noise was measured to be 3.06 muVrms while consuming 7.56 muW of power from a 2.8-V supply corresponding to a noise efficiency factor (NEF) of 2.67 with the theoretical limit being 2.02. When configured for recording LFPs, the amplifier achieved a midband gain of 40.9 dB and a -3-dB bandwidth from 392 mHz to 295 Hz; the input-referred noise was 1.66 muVrms while consuming 2.08 muW from a 2.8-V supply corresponding to an NEF of 3.21. The amplifier was fabricated in AMI´s 0.5-mum CMOS process and occupies 0.16 mm2 of chip area. We obtained successful recordings of action potentials from the robust nucleus of the arcopallium (RA) of an anesthesized zebra finch brain with the amplifier. Our experimental measurements of the amplifier´s performance including its noise were in good accord with theory and circuit simulations.
Keywords :
bioelectric potentials; biomedical electrodes; biomedical electronics; biomedical measurement; brain; low noise amplifiers; low-power electronics; microwave amplifiers; neurophysiology; CMOS process; amplifier fabrication; anesthesized zebra finch brain; arcopallium nucleus; brain-machine interfaces; circuit simulations; common-mode noise rejection; differential pair stage; energy-efficient micropower neural recording amplifier; frequency 392 mHz to 295 Hz; frequency 45 Hz to 5.32 kHz; gain 40.8 dB; gain 40.9 dB; local field potentials; low-noise design techniques; noise efficiency factor; power 2.08 muW; power 7.56 muW; power supply noise rejection; size 0.5 mum; subthreshold operation; voltage 2.8 V; Bandwidth; Differential amplifiers; Energy efficiency; Gain; Low-noise amplifiers; Noise measurement; Noise robustness; Power amplifiers; Power measurement; Power supplies; Action potentials; brain–machine interfaces; brain-machine interfaces; local field potential; low-powe low-noise design; neural-recording amplifier; subthreshold operation;
fLanguage :
English
Journal_Title :
Biomedical Circuits and Systems, IEEE Transactions on
Publisher :
ieee
ISSN :
1932-4545
Type :
jour
DOI :
10.1109/TBCAS.2007.907868
Filename :
4358095
Link To Document :
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