CMOS integrated avalanche photodiodes and frequency-mixing optical sensor front end for portable NIR spectroscopy instruments

Abstract

This paper presents the design and measurement results of two avalanche photodiode structures (APDs) and a novel frequency-mixing transimpedance amplifier (TIA), which are key building blocks towards a monolithically integrated optical sensor front end for near-infrared (NIR) spectroscopy applications. Two different APD structures are fabricated in an unmodified 0.18 \im CMOS process, one with a shallow trench isolation (STI) guard ring and the other with a P-well guard ring. The APDs are characterized in linear mode. The STI bounded APD demonstrates better performance and exhibits 3.78 A/W responsivity at a wavelength of 690 nm and bias voltage of 10.55 V. The frequency-mixing TIA (FM-TIA) employs a T-feedback network incorporating gate-controlled transistors for resistance modulation, enabling the simultaneous down-conversion and amplification of the high frequency modulated photodiode (PD) current. The TIA achieves 92 dS Ω conversion gain with 0.5 V modulating voltage. The measured IIP(3) is 10.6/M. The amplifier together with the 50 Ω output buffer draws 23 mA from a1.8 V power supply.

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

“…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.…”

Review of recent advances in frequency-domain near-infrared spectroscopy technologies [Invited]

“…Alternative approaches based on CMOS-integrated solutions have also been proposed. In 2011, Yun et al [ 59 ] proposed the designs of CMOS-integrated APDs and frequency-mixing transimpedance amplifiers (TIA, converting current from APD to output voltage). The TIA can realize simultaneous down-conversion and amplification of the photodiode current.…”

“…The TIA can realize simultaneous down-conversion and amplification of the photodiode current. In 2013, Sthalekar and Koomson [ 60 ] utilized the TIA architecture from [ 59 ] and proposed a 4-channel sensor design on a 2.25 mm 2 chip for FD-NIRS measurements. The 100 MHz current signals from the photodetector were converted to a high-frequency voltage with the TIA.…”

“…These works [ 59 – 62 ] integrated a single-channel FD-NIRS measurement system on a 2.25 chip, with a dynamic range of 33 dB. It also reached a phase resolution of with a power consumption of 30 mW [ 62 ].…”