Optics and Photonics Journal, 2012, 2, 300-313 http://dx.doi.org/10.4236/opj.2012.24037 Published Online December 2012 (http://www.SciRP.org/journal/opj)
Fully On-Chip Integrated Photodetector Front-End Dedicated to Real-Time Portable Optical Brain Imaging Ehsan Kamrani, Frederic Lesage, Mohamad Sawan Electrical Engineering Department, Ecole Polytechnique, Montreal, Canada Email:
[email protected] Received August 10, 2012; revised September 13, 2012; accepted September 28, 2012
ABSTRACT Optical brain imaging using functional near infra-red spectroscopy (fNIRS) offers a portable and noninvasive tool for monitoring of blood oxygenation. In this paper we have introduced a new miniaturized photodetector front-end on a chip to be applied in a portable fNIRS system. It includes silicon avalanche photodiodes (SiAPD), Transimpedance amplifier (TIA) front-end and Quench-Reset circuitry to operate in both linear and Geiger modes. So it can be applied for both continuous-wave fNIRS (CW-fNIRS) and also single-photon counting. Proposed SiAPD exhibits high-avalanche gain (>100), low-breakdown voltage (
