Exploiting Electrocorticographic Spectral Characteristics for Optimized Signal Chain Design: A 1.08 Analog Front End With Reduced ADC Resolution Requirements

• Published in: IEEE transactions on biomedical circuits and systems Vol. 10; no. 6; pp. 1171 - 1180
• Main Authors: Smith, William A, Mogen, Brian J, Fetz, Eberhard E, Sathe, Visvesh S, Otis, Brian P
• Format: Journal Article
• Language: English
• Published: United States The Institute of Electrical and Electronics Engineers, Inc. (IEEE) 01.12.2016
• Subjects: Amplification; Amplifiers, Electronic; Analog to digital conversion; Analog to digital converters; Brain; Brain-Computer Interfaces; CMOS; Computer applications; Design optimization; Electrocorticography - instrumentation; Electrocorticography - methods; Equalization; Equipment Design; Human-computer interface; Humans; Implants; Signal Processing, Computer-Assisted; Signal-To-Noise Ratio; Variable gain
• ISSN: 1932-4545; 1940-9990
• DOI: 10.1109/TBCAS.2016.2518923

Electrocorticography (ECoG) is an important area of research for Brain-Computer Interface (BCI) development. ECoG, along with some other biopotentials, has spectral characteristics that can be exploited for more optimal front-end performance than is achievable with conventional techniques. This paper optimizes noise performance of such a system and discusses an equalization technique that reduces the analog-to-digital converter (ADC) dynamic range requirements and eliminates the need for a variable gain amplifier (VGA). We demonstrate a fabricated prototype in 1p9m 65 nm CMOS that takes advantage of the presented findings to achieve high-fidelity, full-spectrum ECoG recording. It requires 1.08 μW over a 150 Hz bandwidth for the entire analog front end and only 7 bits of ADC resolution.