Integrated CMOS Optical Sensing Architectures for Frequency-Domain Near-Infrared Spectroscopy.
Yun, Ruida.
2017-04-18T14:05:31.560Z
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Abstract: This work presents the integrated CMOS optical sensor for frequency-domain near-infrared spectroscopy (NIRS), which is rapidly advancing as a cost-effective and efficacious tool for functional studies and imaging of breast tissue, brain tissue, and skeletal muscle. The frequency-domain NIRS (FD-NIRS) is capable of readily measuring tissue optical properties by combining the results using... read morelight at several NIR wavelength (650 nm ~ 950 nm) . The measured tissue optical properties then can be used to generate the image of the tissue for cancer detection. CMOS optical sensor is able to monolithically integrate the photodetector, amplifier and signal conditioning circuitry on the same chip, thus enabling an truly miniaturized noninvasive instrument which is portable, unobtrusive, low-cost, low-power, and robust to motion artifacts. Moreover, each of the building blocks can be optimized to achieve better system performance to fully exploit the benefits of FD-NIRS techniques. Ultimately the CMOS integration would enable the realization of systems for concurrent measurement of multiple diagnostic modalities, thus improving diagnosis validity. System architectures and key building blocks towards the monolithically CMOS integrated phase sensitive optical sensor are extensively investigated in this work. Photodetectors implemented in standard CMOS process are firs studied. CMOS avalanche photodiode, delivering superior responsivity with high bandwidth, is preferred for FD-NIRS system. Detailed derivation reveals that the conventional wideband TIA input noise can be minimized by reducing the TIA bandwidth. Both the zero-crossing phase detector and the mixer phase detector are analyzed in terms of phase noise and phase error. Two integrated optical sensors are implemented in 180 nm CMOS technology for FD-NIRS system. The first one is a monolithically integrated optical sensor using on-chip n-well/p-sub photodiode with zero-crossing phase detector. Experimental results confirmed that the optical sensor exhibits very good linearity for both phase and amplitude measurement. The second one uses a novel frequency-mixing TIA (FM-TIA) to dramatically reduce the front-end noise by implementing a narrowband response. The proposed FM-TIA incorporates a T-feedback resistor network with time varying resistor to simultaneously demodulate and amplify the photodiode current, which can reduce both the design complexity and power consumption. The measurement result reveals more than 15 times noise reduction with good linearity.
Thesis (Ph.D.)--Tufts University, 2011.
Submitted to the Dept. of Electrical Engineering.
Advisor: Valencia Joyner.
Committee: Sergio Fantini, Tom Vandervelde, and Joel Dawson.
Keyword: Electrical engineering.read less - ID:
- 5138js36j
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