A Sub-60- $\mu \text{A}$ Multimodal Smart Biosensing SoC With >80-dB SNR, 35- $\mu \text{A}$ Photoplethysmography Signal Chain

A sub-60-<inline-formula> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula> multimodal analog front-end and ultralow energy biosensing CMOS SoC is presented. A 35-<inline-formula> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula> photoplethysmography (PPG) signal chain that consumes five times lower power than state of the art has been demonstrated. An SNR of >80 dBFS was achieved using circuit and system techniques that enable sub-1% analog duty cycling. Input signal-aware, on-the-fly, real-time data path adaptation algorithms implemented on an external microcontroller and synchronized by an ultralow power on-chip FSM along with a 1.3-<inline-formula> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula>, 14-b, 1-kSPS SAR ADC further lower system energy. A programmable, asynchronous reset capacitive amplifier (PARCA) with noise efficiency factor (NEF) of 4.8 and <inline-formula> <tex-math notation="LaTeX">$dx$ </tex-math></inline-formula>/<inline-formula> <tex-math notation="LaTeX">$dt$ </tex-math></inline-formula> analog feature extractor demonstrates energy efficient electrocardiogram (ECG) capture. A wearable platform using this SoC that simultaneously captures ECG plus PPG and wirelessly transmits the heart rate using Bluetooth low energy every 2 s to a smartphone lasts for greater than five days from a 250-mAhr battery.

[1]  Toshiyo Tamura,et al.  Wearable Photoplethysmographic Sensors—Past and Present , 2014 .

[2]  Rahul Sarpeshkar,et al.  An Ultra-Low-Power Pulse Oximeter Implemented With an Energy-Efficient Transimpedance Amplifier , 2010, IEEE Transactions on Biomedical Circuits and Systems.

[3]  Minkyu Je,et al.  A signal folding neural amplifier exploiting neural signal statistics , 2012, 2012 IEEE Biomedical Circuits and Systems Conference (BioCAS).

[4]  Jan M. Rabaey,et al.  A 0.013mm2 5μW DC-coupled neural signal acquisition IC with 0.5V supply , 2011, 2011 IEEE International Solid-State Circuits Conference.

[5]  E.J. Candes,et al.  An Introduction To Compressive Sampling , 2008, IEEE Signal Processing Magazine.

[6]  B. P. Lathi,et al.  Modern Digital and Analog Communication Systems , 1983 .

[7]  Refet Firat Yazicioglu,et al.  A 30 $\mu$ W Analog Signal Processor ASIC for Portable Biopotential Signal Monitoring , 2011, IEEE Journal of Solid-State Circuits.

[8]  Chung-Yu Wu,et al.  New monolithic switched-capacitor differentiators with good noise rejection , 1989 .

[9]  A.-T. Avestruz,et al.  A 2 $\mu\hbox{W}$ 100 nV/rtHz Chopper-Stabilized Instrumentation Amplifier for Chronic Measurement of Neural Field Potentials , 2007, IEEE Journal of Solid-State Circuits.

[10]  Hao Gao,et al.  21.2 A 3nW signal-acquisition IC integrating an amplifier with 2.1 NEF and a 1.5fJ/conv-step ADC , 2015, 2015 IEEE International Solid-State Circuits Conference - (ISSCC) Digest of Technical Papers.

[11]  K. Glaros,et al.  A Sub-mW Fully-Integrated Pulse Oximeter Front-End , 2013, IEEE Transactions on Biomedical Circuits and Systems.

[12]  Jan M. Rabaey,et al.  A 0.013 ${\hbox {mm}}^{2}$, 5 $\mu\hbox{W}$ , DC-Coupled Neural Signal Acquisition IC With 0.5 V Supply , 2012, IEEE Journal of Solid-State Circuits.

[13]  Charles Sodini,et al.  A wearable vital signs monitor at the ear for continuous heart rate and Pulse Transit Time measurements , 2012, 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[14]  Gabor C. Temes,et al.  Circuit techniques for reducing the effects of op-amp imperfections: autozeroing, correlated double sampling, and chopper stabilization , 1996, Proc. IEEE.

[15]  Robert H. Walden,et al.  Analog-to-digital converter survey and analysis , 1999, IEEE J. Sel. Areas Commun..

[16]  K. Nakajima,et al.  Monitoring of heart and respiratory rates by photoplethysmography using a digital filtering technique. , 1996, Medical engineering & physics.

[17]  Holter Nj,et al.  Remote recording of physiological data by radio. , 1949 .

[18]  N J HOLTER,et al.  Remote recording of physiological data by radio. , 1949, Rocky Mountain medical journal.

[19]  Reid R. Harrison,et al.  A low-power, low-noise CMOS amplifier for neural recording applications , 2002, 2002 IEEE International Symposium on Circuits and Systems. Proceedings (Cat. No.02CH37353).

[20]  Willis J. Tompkins,et al.  A Real-Time QRS Detection Algorithm , 1985, IEEE Transactions on Biomedical Engineering.

[21]  Charles Sodini,et al.  A Low-Power, Dual-Wavelength Photoplethysmogram (PPG) SoC With Static and Time-Varying Interferer Removal , 2015, IEEE Transactions on Biomedical Circuits and Systems.