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ISSCC 2021 ForumsShuenn-Yuh Lee received the B.S. degree from the National Taiwan Ocean

University, Keelung, Taiwan, in 1988, and the M.S. and Ph.D. degrees from the

National Cheng Kung University, Tainan, Taiwan, in 1994 and 1999, respectively. He

is currently a Professor at the Department of Electrical Engineering, National Cheng

Kung University, Tainan, Taiwan. From 2013 to 2016, he serves as the Chairman of

IEEE Solid-State Circuits Society Tainan Chapter. From 2016 to 2017, he serves

as the Vice Chairman of IEEE Tainan Section. He is the Associate Editor of IEEE

Transaction on Biomedical Circuits and Systems from 2016-current. His present

research activities involve the design of analog and mixed-signal integrated

circuits, biomedical circuits and systems, low-power and low-voltage analog

circuits, and RF front-end integrated circuits for wireless communications.


Cardiovascular Disease Detection, Analysis and Evaluation System-On-Chip and Platform

Shuenn-Yuh Lee

[email protected] Department/National Cheng Kung University

February 21, 2021

ISSCC Forum 2 of 78

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Outline Introduction to ECG signal

Low-power wireless ECG acquisition and classification system for body sensor networks

A low-power bidirectional telemetry device with a cardiac microstimulator for implantable body sensor networks

Portable and wireless urine detection system and platform for prevention of cardiovascular disease

ConclusionISSCC Forum 3 of 78


Motivation: Top Ten Causes of Death [1]

[1] https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-deathISSCC Forum 4 of 78

Unit: millions people

20002019


Impulse Conduction & ECG

https://en.wikipedia.org/wiki/Heart

Sinus Node

AV Node

Bundle of His

Bundle Branches

Purkinje Fibers

Sinus Node

AV Node

Bundle of His Right Bundle Branch

Left Bundle Branch

Atrium

Ventricles

Purkinje Fibers

ISSCC Forum 5 of 78


Waves of the ECG (Electrocardiogram)

https://en.wikipedia.org/wiki/ElectrocardiographyISSCC Forum 6 of 78

P wave: atrial depolarizationQRS wave: ventricular depolarization

T wave: ventricular repolarizationU wave: slow repolarization of papillary muscles


ECG Patch Requirement

Monitoring time Classification Adjustment Feedback Representative

graph

Holter 24-48 hrs off line Y N

Zio Patch 7 days off line N NRefit Patch 8 hrs on line N

N

Leadtek(amor H1) 24 hrs N N N

(0.05~40HZ)

This work

>24 hrs6 months (off-line)

on line Y Y(0.05Hz ~ 150Hz)

ISSCC Forum 7 of 78


Challenges Home-care system

Long-term usage

Low-power consumption

Convenient usage

Wireless transmission

High resolution

For diagnosing precisely

Diagnosis

For both user and the doctorISSCC Forum 8 of 78


Interactive Intelligent Healthcare System Targets Low power, Anywhere, Anytime, Long-term monitoring

Body Sensor Network Near-body application Wearable device

Local Sensor Network Portable device (smartphone, notebook, PDA)

ISSCC Forum 9 of 78








Low-power Wireless ECG Acquisition Circuit and System for Body Sensor Networks Pro of SOC

Personal device

Cloud server

HW & SW

Special in our SOC

Self-developed SOC

Low cost, low power

High flexibility & reliabilityISSCC Forum 11 of 78


Proposed System Overview

Bio-signal processor (BSP): Signal acquisition and digitization Transceiver: wireless transmission for 1 meter distance Digital-signal processor (DSP): Signal classification

ISSCC Forum 12 of 78


Proposed System Overview

Simple BSP architecture with high resolution Transceiver with low power consumption Signal feature extraction and classification



Bio-Signal Processor Conventional BSP design (Analog front-end circuits)

Conventional design strategy Simple architecture with lower resolution Complex architecture with higher resolution Performance is always limited by filters (< 8-10 bits)



Proposed Bio-Signal Processor

Eliminate the low-frequency noises, ex: flicker noise, dc offset

Remove the filter circuit

Digitizing directly by the high-pass sigma delta modulator (HPSDM)ISSCC Forum 15 of 78


Proposed Bio-Signal Processor (cont.) Advantages of the BSP: Simple architecture: prone to be integrated High performance: by applying SDM and eliminating the filter One bit stream output: Reduce parallel-to-serial circuits Against transmission error: reduce encoding/ encryption circuit

Specifications: Architecture CBCTA+HPSDMClose loop gain > 20dB

Resolution > 10bitsBandwidth 200Hz

Chopping frequency 25.6kHzSampling frequency 51.2kHz

OSR 128Output format modulated 1-bit

stream Power consumption As low as possible



High Pass Sigma Delta Modulator (of BSP)Spec. Value Unit Implementation ParametersENOB > 12 bit Architecture DTSDM

Oversampling Ratio 128 Hz/ Hz Modulator order 3 OrderBandwidth 200 Hz Quantizer 1 Bit

Sampling Freq. 51.2k HzTopology Feed-forward with local

feedback pathMax. Input -20 dBV

-1

-1z

1+z

-1

-1z

1+z-1

-1z

1+za1 2.5 g1 0.333

a2 1.25 g2 0.667

a3 1.25 g3 0.179b1 0.01

Coefficient table



High Pass Sigma Delta Modulator (of BSP) High-pass integrator [2]

[2] V. T. Nguyen, et. al., “VHDL-AMS behavioral modeling and simulation of high-pass delta-sigma modulator,” IEEE BMAS 2005)



High Pass Sigma Delta Modulator (of BSP) Circuit schematic & capacitor values

CS1 0.17pF CI1 0.51pF CH1 1.02pF CA1 0.10pF



CI4 0.04pF CB1K 2.71pF CB1 0.10pF



Simulation Results of the BSP One tone & two-tone test SNR > 72 dB SFDR > 72 dB



Specifications of the BSPGeneral

Technology TSMC 0.18 μm 1P6M processSupply voltage 1.2 V

CBCTAMid-band gain 20/ 24/ 28 dB

PSRR 73.8 dBCMRR 109.6 dB

Input refer noise 1.2 μVRMS (25.4–25.6 kHz)SFDR 76.34 dB (with 5,000 μV input)

Chopper frequency 25.6 kHzPower consumption 15 μW

HPSDMArchitecture High-pass, third-order, feed-forward SDM

SNR 72 dB (with 0.1 V input signal)SFDR 75.4 dB (with two-tone test)

Oversampling ratio 128Sampling frequency 51.2 kHzPower consumption 13.5 μW

Entire BSP circuitsPower consumption 28.7 μW

Resolution > 12 bits



Transceiver The demands of wireless transmission for the proposed BSNs Low power: for long-term usage

Short-range transmission: for 1-meter distance

Simple architecture: for system integration

Considerations of the specifications Safety is the must concerned issue on the BSNs

Frequency selection

Transmission power & distance

Data rate, power consumption & architectureISSCC Forum 22 of 78


Transceiver (cont.) Consideration of the specifications Safety: SAR (Specific Absorption Rate) versus frequency [3] Frequency selection Transmission power & distance

[3] E. Cocherova, et. al. “Dependence of the RF field absorption on the human body dimensions,” International Conference Radioelektronika, 2009.



Transceiver (cont.) Consideration of the specifications Safety Frequency selection: ISM Band Transmission power & distance

Frequency range Center frequency Availability

13.553-13.567 MHz 13.560 MHz -26.957-27.283 MHz 27.120 MHz -

40.66-40.70 MHz 40.68 MHz -433.05-434.79MHz 433.92 MHz ITU Region I only

902-928 MHz 915 MHz ITU Region II only2.400-2.500 GHz 2.45 GHz -5.725-5.875 GHz 5.800 GHz -

Region 1, 2 & 3 [4]

[4] http://life.itu.int/radioclub/rr/frr.htm



Transceiver (cont.) Consideration of the specifications Transmission power & distance

Assume that Transmitter is mounted on the body : 1cm or 2cm (R) thickness transmitting power: -10 dBm (Pt), antenna gain: 0 dBi (Gt) Power density => 0.08 and 0.02 W/m2 => safety

Power density (W/m2)Controlled exposure(6 minutes average)

Uncontrolled exposure(6 minutes average)

IEEE [8] 80 50ICNIRP [9] 50 10

2 ( )4

t tPGPower Density SRπ

=

[5] IEEE Standard C95.1-1999,[6] ICNIRP safety guideline, April 1998.



Transceiver (cont.) Consideration of the specifications Data rate, Power consumption & architecture

Architecture Sensitivity Data rateCircuit

complexity

Power

consumption

Super

Heterodyne★★ ★★ ★★ ★★

Direct

Conversion★☆ ★☆ ☆☆ ★☆

Low IF ★☆ ★☆ ★☆ ★☆Super

Regenerative☆☆ ☆☆ ☆☆ ☆☆



Transceiver (cont.)

Architecture comparison Super-regenerative: Sensitivity ↓, Power ↓, Circuit complexity ↓



Super-regenerative Transceiver

Transmitter: VCO, buffer, modulator Receiver: LNA, VCO, current steering DAC, envelop detector, comparator



Transceiver (cont.) Specifications:

Architecture Super regenerative OOK transceiver

Transmission distance 1 meterTransmitter

Output power > -20dBmAntenna gain 0dBi

Output frequency 2.4GHz~ 2.48GHz (ISM band)Receiver

Sensitivity < -60dBmAntenna gain 0 dBi

Received frequency 2.4GHz – 2.48GHz



Digital Signal Processor

Two main functions:

Signal demodulation: shifting back the bio-signal

Signal analysis: using wavelet transform for ECG classificationISSCC Forum 30 of 78


Digital Signal Processor- WT (cont.) Beat detection

R-wave

Beats per minute

Classification

Compare the results

From MCS



Digital Signal Processor (cont.)

Main function

DemodulationDecimation

Coefficient extraction by Wavelet

transformBeat detection

DecimatorDecimation rate 128

Resolution >10 bitsWavelet transformer

Resolution > 8bitsISSCC Forum 32 of 78


Chip Implementation TSMC 0.18μm 1P6M standard process with supply voltage of 1.2V BSP +TX: 1.55 x 1.51 mm2

RX + decimator: 1.28 x 2.04 mm2

DSP (wavelet transform) : 1.57 x 1.57 mm2

BSP+TX RX+decimator DSP



Summary A wireless ECG acquisition and classification system is proposed BSN architecture High-performance : > 10 bits Low power consumption : body-end circuits operated> 100 days Wireless transmission : 1 meter distance ECG classification : storing 8 kinds of reference data Simplified architecture

3 chips implementation Body-end circuits: BSP + TX Receiving-end circuits: RX + decimator, Wavelet transformer



Demo Platform



Applications (Replace Holter) Arrhythmia monitoring system

1.69 mm

1.73

mm

CCTA HPSDM

DSP



Ch1：V5

Ch2：V1

Ch3：Lead III

Dotted circles：Our device (ECG patch)

Method (Holter Medical Device)White(1-)

Blue(3-)Black(2-)

Red(1+)

Orange(3+)

Brown(2+)

Green(RL, GND)



Patients use two devices at the same time Check the relationship between our device and Holter

Self-developed APP

Method (Holter Medical Device)

Similar with Ch3 and the rhythm is almost the same. A PVC is classified by ECG Patch and Holter



VPB ：ventricular premature beat (also called PVC) VT ：ventricular tachycardia SVPB ：supraventricular premature beats (also called APC) SVT ：supraventricular tachycardia

Holter Format



No.200 in MIT-BIH arrhythmia database Rate: 60-100 bpm Regularity: irregular P waves: abnormal-not present on VPC PR interval: miss QRS duration: bizarre and >0.12 sec.

Premature Ventricular Contraction (PVC)



No.100 in MIT-BIH arrhythmia database Rate: 60-100 bpm Regularity: occasionally irregular P waves: normal PR interval: 0.12-0.20 sec QRS duration: 0.04-0.12 sec.

Atrial Premature Contraction (APC)



No.205 in MIT-BIH arrhythmia database Rate: >100 bpm Regularity: irregular P waves: not present on VPC (three or more) PR interval: miss QRS duration: 0.04-0.12 sec.

Ventricular Tachycardia (VT)



The Bluetooth connection is stable 24 hours data recorded Normal rhythm

Similar with Ch3 and the rhythm is the same

Fifth Patient in Tainan Hospital



An APC occurred Detected by Holter & our device

Noted as red circle

Fifth Patient in Tainan Hospital (cont.)



PVC pair occurred Noted as red circle

Fifth Patient in Tainan Hospital (cont.)



Summary A bio-signal acquisition and arrhythmia classification system is proposed

and implemented in TSMC 0.18 μm standard CMOS process. The AFE has 10 bits resolution digital output and its power consumption is

28.7 μW. A wavelet based QRS detection and arrhythmia classification method was

proposed. The accuracy in terms of sensitivity and positive predictionbased on the MIT-BIH arrhythmia database are 99.44% and 99.40%,respectively. The accuracy of arrhythmia classification is 95.83 %.

There are more than 100 patients are enrolled in the clinical trial. Thearrhythmias can be detected by Holter and also classified by our device.

Yutech Co., Ltd. (start-up company): Founded in May of 2019 at Tainan,Taiwan (https://www.yutechealth.com/index_en.html)









Motivation Therapy by micro-stimulation



A low-power cardiac microstimulator for implantable body sensor networks

System overview

Circuitry design

Experimental results

Summary



System Overview Problem in conventional devices: large volume and high power

consumption Improved by four blocks: powering interface, digital circuitry, pacing

channel, sensing channel



Proposed Close-Loop Micro-Stimulator Powering interface: RF front-end, charging circuit, charge pump Digital circuitry: PSK demodulator, system controller Pacing channel: Micro-stimulator Sensing channel: Amplifier, filter, ADC, LSK modulator




System overview

Circuitry design

Experience results

Summary



Powering Interface Main features: rechargeable device, LDO regulator, high efficient

charge pump Small battery body Stable AC/DC converter and DC/DC converter



Digital Circuitry


Provide programmable functions and enhance reliability of communication PLL based PSK demodulator System controller flow chart


Pacing Channel

Atrial Strength-Duration Curve



Sensing Channel




System overview

Circuitry design

Experience results

Summary



Chip Microphotograph TSMC 0.35µm 2P4M 1.5×1.6mm2

Wireless telemetry pacemaker test setup

Coils radius: 12.5mm / 7.5mm

Distance : 10mm~20mm



System Functions



Programmable Function Pulse amplitude, pulse duration, pulse frequency



Measurement- Close Loop Test



In Vivo Study



Measured SummaryGeneral

Technology TSMC 0.35µm 2P

Chip area 1.25×1.85mm2

Carrier frequency 256kHzPower Interface and Pacing Channel

Rectifier 2 V output with induced 2.9 Vpp

Regulator power 7 µW @ 1V

Charge Pump

power 10 μWoutput voltage

(@ 1 V input voltage) 3.2 V

pumping clock frequency 16 kHz

PowerManagement

(Supply Detector,Charge Detector,

and Charger)

power 20 μWcharging current 2 mA

Battery(6 mAh @ 1.2 Vsupply voltage)

2 x V6HR,(1000 times recharging)

D/A Controllerpower 42nW @ 1V

operation frequency 8 kHz

Pulse Generatorpower

(pacing period = 1s;pulse duration = 0.5ms)

15.5µW @ 5.8V

Digital Blocks

PSK Demodulator power 1.76µW @ 1Vsampling frequency 4MHz

System Controller power 260nW @ 1Voperation frequency 32kHz

ProgrammableRanges

stimulation frequency 0.5–31.25 Hzstimulus amplitude 0–3.2 V

stimulus duration 62.5 μs–1.94 ms

Monitoring Analog Front End @ 1.4V

Preamplifier

power 40nWInput referred noise 1.1µVrms

3-dB bandwidth 0-140HzDC gain 21/31dB

Biquad Low-Pass/Band-Pass Filter

power 126 nW(with buffer)

3-dB BandwidthLow-Pass 0–15 HzBand-Pass 15–80 Hz

Real-time Detection ADC

power 71nW(with SCAMP)

resolution 8bitssampling frequency 800Hz

sample-and-hold gain 2/5 times



Summary

Proposed a programmable implantable micro-stimulator

SoC with wireless telemetry

Smart powering management: reduce the device volume

Low power analog front end sensing channel: enhance the

battery life

Wireless telemetry: on-line monitor and programming

Programmable control: multi-function stimulationsISSCC Forum 64 of 78








Motivation

Around 15% people in 75years and older group sufferfrom valvular heart disease

Provides a telecare platform to monitor the risks of cardiovascular disease (CVD) and prevent CVD



Proposed Electrochemical Sensing System


RDAC

VCM

Potentiostat

Current-sensing VCO-based SDM

RW2

MUX

C

W

Sel [1:0]W3W1

Controller +Decimator +

UART

MCU+BLE(CYBLE-022001) ADC Output

DAC Output

UART

Power Management

Bandgap Reference

3.3V/1.8V LDO

T18_109B Chip


UACR sensor (Urine Albumin and Creatinine Sensors)

68 of 78

Creatinine sensor

SPCE|ABTS-CNT|Nafion® electrode

Albumin sensor

SPCE|Au|Ab-HSAimmunosensor• Sensitivity: 27.3 ± 0.5 µA cm-2 mM-1

• LOD: 11.0 µM• linear range: 16.5mM ~26.84mM

ISSCC Forum


Urine Detection Circuit Right: Conventional architecture of potentiostat with the TIA-topology

Left: Proposed readout circuit with direct connection to sensor in potentiostatPotentiostat

Vout

R

C

W

RTIA

ADC

DAC

DOUT

DIN

Readout Circuit

Potentiostat

R

C

W

DACDIN

Proposed ASIC

Current-sensing VCO-based SDM

185Hz

UART Package

DOUT



CTDSM Topology

Current-sensing VCO-based 2nd-order noise shaping



Dout

sens

or

Cin

Gm

Vbias

Vc

H(s) CCO

CCO

DAC

Iin

I dac

Dual-CCO

Intrinsic CLA

Transfer functions & Coefficients in each stage

Proposed Architecture

∆𝑉= 𝐼𝑠𝐶 = 𝑘𝑠 = 𝑎 𝑓𝑠

∆𝜑 𝑠∆𝑉 = 2𝜋𝐾𝑠 = 𝑘𝑠 = 𝑎 𝑓𝑠→ 𝒂𝟏 = 𝑰𝒊𝒏𝑪𝒊𝒏 · 𝒇𝒔

→ 𝒂𝟐 = 𝟐𝝅𝑲𝑽𝒇𝒔

First-stage

Second-stage

71 of 78ISSCC Forum


Circuit Realization

Irefn DiDib

Irefp

15 unit NMOS

cells

I

7.5I

Passive integrator + Dual-CCO structure

Current-steering DAC

15-stage Ring CCO 15-stage Ring CCO

1515

Vin Vbias

Degeneration R-DAC

XOR

DFF Thermometer-to-Binary Adder

15

16

fs

II15

Iin

7.5I

Decoder

ID

R+ R-

ᶵ15

4

4-bit DOUT

Cin If

72 of 78ISSCC Forum

CCO: current controlledring oscillator


Measurement Result



ASIC Microphotography and Comparison Table


Power Eff.: Input Range/Maximum Consumed Current


Measurement Results and Experimental Setup



Conclusion

The low-power SOC for out-of/implantable body sensor

networks are introduced

The required challenged circuits, including analog front-end

circuits, passive/active RF front-end circuits, power

management, and digital processing circuits, are presented

A smart application platform to evaluate cardiovascular status of

patients based on the outcomes in clinical research is developed



Include Key References Hao-Yun Lee, et. al., “A Power-Efficient Current Readout Circuit with VCO-Based 2nd-Order CT Δ∑ ADC for

Electrochemistry Acquisition,” Accepted by 2020 IEEE A-SSCC, Nov. 2020. Ju-Yi Chen, et. al., “Urine N-terminal pro b-type natriuretic peptide is predictive of heart-failure–related emergency

department visits,” ESC Heart Failure, 02 July 2020, DOI: 10.1002/ehf2.12856. Ding-Siang Ciou, et. al.,, “Colorimetric and Amperometric Detection of Urine Creatinine Based on the ABTS Radical

Cation Modified Electrode,” Sensors & Actuators: B. Chemical vol. 314, July 2020, 128034. Shuenn-Yuh Lee, et. al., “A 2.4 GHz ISM Band OOK Transceiver with High Energy Efficiency for Biomedical Implantable

Applications” IEEE TBioCAS, Feb. 2020. Shuenn-Yuh Lee, et. al., “Electrocardiogram and Phonocardiogram Monitoring System for Cardiac Auscultation,” IEEE

Trans. on Biomedical Circuits and Systems, Dec. 2019. Shuenn-Yuh Lee, et. al., “Development of an Arrhythmia Monitoring System and Human Study,” IEEE Trans. on

Consumer Electronics, Nov. 2018 Shuenn-Yuh Lee, et. al., “Low-Power Wireless ECG Acquisition and Classification System for Body Sensor Networks”,

IEEE Journal of Biomedical and Health Informatics. Jan. 2015. Shuenn-Yuh Lee, et. al., “A Wireless Front-end with Power Management for an Implantable Cardiac Micro-Stimulator,”

IEEE Trans. on Biomedical Circuits and Systems, Feb. 2012. Shuenn-Yuh Lee, et. al., “A Programmable Implantable Micro-stimulator SoC with Wireless Telemetry: Application in

Closed-Loop Endocardial Stimulation for Cardiac Pacemaker,” IEEE TBioCAS, Dec. 2011.



Acknowledgement Animal study: thanks for the support of Prof. Y. Y. Chen, National Yang-Ming University,

Taiwan

Thanks all of the students in the CBIC Lab and Doctor J. W. Lin as the acting chairman of the Cardiovascular Center of National Taiwan University Hospital Yun-Lin Branch

Thanks all of co-operated professors (Doctor Ju-Yi Chen) in NCKU hospital

Thanks for Your Attentions !ISSCC Forum 78 of 78

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