A Monolithically Integrated Phase-Sensitive Optical Sensor for Frequency-Domain NIR Spectroscopy

Abstract

This paper presents design and measurement results of a fully integrated optical sensor for phase and amplitude detection of RF modulated optical signals up to 110 MHz in the near-infrared (NIR) region (650-850 nm) for use in frequency-domain spectroscopy instruments. The sensor consists of an NIR-sensitive photodetector monolithically integrated with a front-end analog amplifier and signal processing circuitry for amplitude and phase detection in an unmodified complementary metal oxide semiconductor (CMOS) process. A high-gain, low-noise differential transimpedance amplifier (TIA) is implemented to amplify the photocurrent signal. Amplitude and phase resolution are evaluated with a 690 nm laser diode modulated at 100 MHz. The amplitude response exhibits 2.2 mV Wresolutionwith0.4%linearity.The measured amplitude output noise is 72 V. The proposed phase detector detects 0 -360 phase difference with a measured average phase resolution of 4.8 mV/degree and 255 V output noise. The sensor is implemented in a 180 nm CMOS technology and consumes 23.4 mW from a 1.8 V supply voltage.

Prospects and limitations of non-invasive blood glucose monitoring using near-infrared spectroscopy

“…Advanced silicon micro-fabrication processing, such as Complementary Metal Oxide Semiconductor (CMOS) technology, allows monolithic integration of photodetectors and signal conditioning circuitry on a single chip. Thus, for miniaturized design of a microspectrophotometer, the use of CMOS will be beneficial for application in non-invasive glucose monitoring [147][148][149][150]. It is inferred from the above analysis that accurate and reliable NIRS based non-invasive glucose measurement requires significant improvement to replace the conventional blood glucose measurement methods.…”

A CMOS Sensor for Measurement of Cerebral Optical Coefficients Using Non-Invasive Frequency Domain Near Infrared Spectroscopy

“…3 is chosen. The wideband TIA architecture is adapated from [30]- [32] with a single fixed resistor feedback as opposed to a T-Feedback structure. In [31], the T-feedback structure was implemented to enable frequency mixing using a variable resistance in feedback.…”

High Gain CMOS Transimpedance Amplifier For Near Infrared Spectroscopy Applications

“…At a proper frequency, a peak can be generated through the imaginary part of ZT, i.e., jωL, through which the channel high-frequency signal loss can moderately be compensated. For improving the output bandwidth, it is possible to select the inductor value for resonating with the parasitic capacitance if transmitted pulse data rate is greater than pole frequency obtained through equivalent RC low-pass filter at termination node [16].…”