Micropower CMOS integrated low-noise amplification, filtering, and digitization of multimodal neuropotentials

Mohsen Mollazadeh, Kartikeya Murari, Gert Cauwenberghs, Nitish V Thakor

Research output: Contribution to journalArticle

Abstract

Electrical activity in the brain spans a wide range of spatial and temporal scales, requiring simultaneous recording of multiple modalities of neurophysiological signals in order to capture various aspects of brain state dynamics. Here, we present a 16-channel neural interface integrated circuit fabricated in a 0.5 μm 3M2P CMOS process for selective digital acquisition of biopotentials across the spectrum of neural signal modalities in the brain, ranging from single spike action potentials to local field potentials (LFP), electrocorticograms (ECoG), and electroencephalograms (EEG). Each channel is composed of a tunable bandwidth, fixed gain front-end amplifier and a programmable gain/ resolution continuous-time incremental ΔΣ analog-to-digital converter (ADC). A two-stage topology for the front-end voltage amplifier with capacitive feedback offers independent tuning of the amplifier bandpass frequency corners, and attains a noise efficiency factor (NEF) of 2.9 at 8.2 kHz bandwidth for spike recording, and a NEF of 3.2 at 140 Hz bandwidth for EEG recording. The amplifier has a measured midband gain of 39.6 dB, frequency response from 0.2 Hz to 8.2 kHz, and an input-referred noise of 1.94 μVrms while drawing 12.2 μA of current from a 3.3 V supply. The lower and higher cutoff frequencies of the bandpass filter are adjustable from 0.2 to 94 Hz and 140 Hz to 8.2 kHz, respectively. At 10-bit resolution, the ADC has an SNDR of 56 dB while consuming 76 μW power. Time-modulation feedback in the ADC offers programmable digital gain (1-4096) for auto-ranging, further improving the dynamic range and linearity of the ADC. Experimental recordings with the system show spike signals in rat somatosensory cortex as well as alpha EEG activity in a human subject.

Original languageEnglish (US)
Pages (from-to)1-10
Number of pages10
JournalIEEE Transactions on Biomedical Circuits and Systems
Volume3
Issue number1
DOIs
StatePublished - 2009

Fingerprint

Analog to digital conversion
Digital to analog conversion
Amplification
Electroencephalography
Brain
Bandwidth
Bandpass amplifiers
Feedback
Bioelectric potentials
Cutoff frequency
Bandpass filters
Frequency response
Integrated circuits
Rats
Tuning
Topology
Modulation
Electric potential

Keywords

  • Analog VLSI
  • Biopotential amplifier
  • Digital telemetry
  • Electrocorticogram
  • Electroencephalogram
  • Local field potentials
  • Micropower instrumentation
  • Neural interface

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Biomedical Engineering

Cite this

Micropower CMOS integrated low-noise amplification, filtering, and digitization of multimodal neuropotentials. / Mollazadeh, Mohsen; Murari, Kartikeya; Cauwenberghs, Gert; Thakor, Nitish V.

In: IEEE Transactions on Biomedical Circuits and Systems, Vol. 3, No. 1, 2009, p. 1-10.

Research output: Contribution to journalArticle

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