A Neural Recording Amplifier with Low-Frequency Noise Suppression

Takeshi YOSHIDA  Yoshihiro MASUI  Ryoji EKI  Atsushi IWATA  Masayuki YOSHIDA  Kazumasa UEMATSU  

IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.6   pp.849-854
Publication Date: 2010/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.849
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
neural recording amplifier,  neural signal sensing LSI,  1/f noise,  autozero technology,  

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To detect neural spike signals, low-power neural signal recording frontend circuits must amplify neural signals with below 100 µV amplitude and a few hundred Hz frequency while suppressing a large DC offset voltage, 1/f noise of MOSFETs, and induced noise of AC power supply. To overcome the problem of unwanted noise at such a low signal level, a low-noise neural signal detection amplifier with low-frequency noise suppression scheme was developed utilizing a new autozeroing technique. A test chip was designed and fabricated with a mixed signal 0.18-µm CMOS technology. The voltage gain of 39 dB at the bandwidth of the neural signal and the gain reduction of 20 dB at AC supply noise of 60 Hz were obtained. The input equivalent noise and power dissipation were 90 nV/root-Hz and 90 µW at a supply voltage of 1.5 V, respectively.