A Rugged Wearable Modular ExG Platform Employing a …efficiency.ucsd.edu/.../2012/09/UCSD-ISSCC19-FM-ExG.pdf · 2019. 10. 31. · A Rugged Wearable Modular ExG Platform Employing

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 1 of number of slides

A Rugged Wearable Modular ExG Platform Employing a Distributed Scalable Multi-Channel

FM-ADC Achieving 101dB Input Dynamic Range and Motion-Artifact Resilience

J. Warchall1, P. Theilmann2, Y. Ouyang2, H. Garudadri1, P. P. Mercier1

1University of California, San Diego, La Jolla, CA 2MaXentric Technologies, La Jolla, CA

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 2 of number of slides

Clinical-Grade EEG

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 3 of number of slides

Clinical-Grade EEG

Range (with Motion): 1 μV ⬌ ~100 mV

100 dB DRBandwidth:

0.5Hz ⬌ ~250Hz

Data from https://jp.mathworks.com/

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 4 of number of slides

Clinical-Grade EEG Challenges

http://people.brandeis.edu/~sekuler/ https://www.cne.psychol.cam.ac.uk/ https://tragicoptimist.wordpress.com/

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 5 of number of slides

Clinical-Grade EEG Challenges

http://people.brandeis.edu/~sekuler/ https://www.cne.psychol.cam.ac.uk/ https://tragicoptimist.wordpress.com/

Lots of Wiring – Fragile and Bulky Cable Sway Introduces Motion Artifacts

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 6 of number of slides

Commercial Wireless EEG ChallengesIMEC Emotiv Cognionics

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 7 of number of slides

Commercial Wireless EEG ChallengesIMEC Emotiv Cognionics

63dB SNR8 Channels96 Hour Battery

84dB SNR14 Channels12 Hour Battery

112dB SNR64 Channels6 Hour Battery

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 8 of number of slides

Commercial Wireless EEG Challenges

Choose: Long Battery Life OR High Fidelity/Density

IMEC Emotiv Cognionics

63dB SNR8 Channels96 Hour Battery

84dB SNR14 Channels12 Hour Battery

112dB SNR64 Channels6 Hour Battery

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 9 of number of slides

Presentation Outline1. Motivation

Increase Battery Life and Ruggedness for EXGMaintain High Dynamic Range and High Density

2. ApproachA Scalable Multi-Channel FM-FDM Sensor NetworkIntegrated Gateway with ADC and UWB TX

3. Measurement ResultsSingle Channel MeasurementsMulti-Channel MeasurementsBiopotential MeasurementsUWB Performance

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 10 of number of slides

EXG – The Traditional Approach

Warchall, et al. ISCAS 2016

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 11 of number of slides

EXG – The Traditional Approach

Warchall, et al. ISCAS 2016

• N wires for N Channels• Fragile and Bulky• Exacerbate Motion Artifacts

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 12 of number of slides

EXG – The Traditional Approach

Warchall, et al. ISCAS 2016

• N wires for N Channels• Fragile and Bulky• Exacerbate Motion Artifacts

• Long Wires in Baseband• Require Active Electrode

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 13 of number of slides

EXG – The Traditional Approach

Warchall, et al. ISCAS 2016

• N wires for N Channels• Fragile and Bulky• Exacerbate Motion Artifacts

• Long Wires in Baseband• Require Active Electrode

• N ADCs• High ENOB• High Power Consumption

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 14 of number of slides

EXG – An FM-FDM Approach

Warchall, et al. ISCAS 2016

FM-FDM:

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 15 of number of slides

EXG – An FM-FDM Approach

Warchall, et al. ISCAS 2016

FM-FDM:

Minimizes Wire Count,

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 16 of number of slides

EXG – An FM-FDM Approach

Warchall, et al. ISCAS 2016

FM-FDM:

Minimizes Wire Count,

Mitigates Cable Sway,

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 17 of number of slides

EXG – An FM-FDM Approach

Warchall, et al. ISCAS 2016

FM-FDM:

Minimizes Wire Count,

Mitigates Cable Sway,

Minimizes ADC Count

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 18 of number of slides

Why FM Multiplexing?Other Multiplexing Possibilities:• Serial Digital (TDM, I2C, SPI, etc.)

• Requires N ~100dB DR ADCs for N channels

• FDM Digital (OOK, BPSK, QPSK, etc.)• Still requires N ~100dB DR ADCs

• AM-FDM• Requires one ~100dB DR ADC

Warchall, et al. ISCAS 2016

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 19 of number of slides

Why FM Multiplexing?Other Multiplexing Possibilities:• Serial Digital (TDM, I2C, SPI, etc.)

• Requires N ~100dB DR ADCs for N channels

• FDM Digital (OOK, BPSK, QPSK, etc.)• Still requires N ~100dB DR ADCs

• AM-FDM• Requires one ~100dB DR ADC

• FM-FDM• Single low bit depth high sample rate ADC• Leverages oversampling converter efficiency Warchall, et al.

ISCAS 2016

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 20 of number of slides

Why FM Multiplexing?

FM-FDM Also Reduces ADC Complexity, Maintains High DR

Other Multiplexing Possibilities:• Serial Digital (TDM, I2C, SPI, etc.)

• Requires N ~100dB DR ADCs for N channels

• FDM Digital (OOK, BPSK, QPSK, etc.)• Still requires N ~100dB DR ADCs

• AM-FDM• Requires one ~100dB DR ADC

• FM-FDM• Single low bit depth high sample rate ADC• Leverages oversampling converter efficiency Warchall, et al.

ISCAS 2016

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 21 of number of slides

A Rugged Wearable Modular ExG Platform

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 22 of number of slides

A Rugged Wearable Modular ExG Platform

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 23 of number of slides

A Rugged Wearable Modular ExG Platform

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 24 of number of slides

A Rugged Wearable Modular ExG Platform

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 25 of number of slides

A Rugged Wearable Modular ExG Platform

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 26 of number of slides

A Rugged Wearable Modular ExG Platform

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 27 of number of slides

Bandwidth Expansion

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 28 of number of slides

Bandwidth Expansion

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 29 of number of slides

Bandwidth Expansion

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 30 of number of slides

Bandwidth Expansion

Really?

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 31 of number of slides

Phase Noise in FM VCO

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 32 of number of slides

Phase Noise in FM VCO

Low VCO Phase Noise Maintains High System SNR

Target Area

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 33 of number of slides

Active Electrode Design

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 34 of number of slides

Active Electrode Design

Low Phase Noise

Maintains High SNR

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 35 of number of slides

Active Electrode Design

Low Phase Noise

Maintains High SNR

Low Power

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 36 of number of slides

Active Electrode Design

Low Phase Noise

Maintains High SNR

Low Power

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 37 of number of slides

Active Electrode Design

Low Phase Noise

Maintains High SNR

Low PowerNonlinear

V-to-CRelationship!

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 38 of number of slides

Active Electrode NonlinearityElectrode Input System Output

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 39 of number of slides

Active Electrode NonlinearityElectrode Input System Output

DerivePolynomialTransform

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 40 of number of slides

Active Electrode Nonlinearity

Calibration Gains~20dB SNDR!

Electrode Input System Output

DerivePolynomialTransformWith

Calibration:

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 41 of number of slides

Gateway Power SavingNyquist Sampling

FM Channels Higher Frequency à Lower Varactor Nonlinearity

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 42 of number of slides

Gateway Power SavingNyquist Sampling

Wasted Spectrum

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 43 of number of slides

Gateway Power Savingfs ≈ 30 MHz Sampling Power:

3 MilliwattsNyquist Sampling

Wasted Spectrum

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 44 of number of slides

Gateway Power Savingfs ≈ 30 MHz Sampling Power:

3 Milliwatts

Baseband Aliases of FM Channels

Nyquist Sampling

Bandpass Sampling

Wasted Spectrum

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 45 of number of slides

Gateway Power Saving

fs ≈ 1 MHz

fs ≈ 30 MHz Sampling Power:3 Milliwatts

Sampling Power:100 Microwatts

Baseband Aliases of FM Channels

Nyquist Sampling

Bandpass Sampling

Wasted Spectrum

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 46 of number of slides

Gateway Power Saving

Bandpass SamplingReduces Sampling

Power by ~30x

fs ≈ 1 MHz

fs ≈ 30 MHz Sampling Power:3 Milliwatts

Sampling Power:100 Microwatts

Baseband Aliases of FM Channels

Nyquist Sampling

Bandpass Sampling

Wasted Spectrum

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 47 of number of slides

Two Chip System Implementation1mm 1mm

1mm

Active Electrode IC5 – VCO6 – Tuned Drive Amplifier

Gateway IC1 – UWB TX2 – Pulse Shaper

3 – Serializer/Coder4 – SAR ADC

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 48 of number of slides

Single Channel Measurement Results

Full-Scale 10mVpp 10Hz

Sine TestMessage

Probed at VCO Output

~50KHz BW

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 49 of number of slides

Single Channel Measurement Results

SNR = 101dB

Full-Scale 10mVpp 10Hz

Sine TestMessage

After FMDemodulation

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 50 of number of slides

Single Channel Measurement Results

101dB max SNR84dB max SNDR

VariousAmplitudeSine TestMessages

After FMDemodulation

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 51 of number of slides

Single Channel Measurement Results

Single ChannelInput Step Test

After FMDemodulation

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 52 of number of slides

Single Channel Measurement Results

Single ChannelInput Step Test

After FMDemodulation

FM-ExGActive ElectrodesDo Not Saturate

For 10x Input Step

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 53 of number of slides

Multi-Channel Measurement Results

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 54 of number of slides

Multi-Channel Measurement Results

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 55 of number of slides

Biopotential Measurement Results

FM-ExG(μV)

OpenBCI(μV)

At Rest In Motion

MotionArtifacts

FM à Avoids In-Band CouplingFewer Wires à Reduced Electrode Inertia

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 56 of number of slides

Biopotential Measurement Results

FM-ExG(μV)

OpenBCI(μV)

At Rest In Motion

MotionArtifacts

FM-EXG Reduces Motion Artifact SeverityIn-Motion to At-Rest Peak MATLAB xcorr 2.9x Higher

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 57 of number of slides

Biopotential Measurement Results

Target Peak

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 58 of number of slides

UWB TX Measurement Results

PS

D (

dBm

/MH

z)

RBW = 1MHzVBW = 1MHz

1 2 3 4 5 6 7 8 9 10Frequency (GHz)

FCC Spectral Mask

1400 1600 1800 2000 2200

Student Version of MATLAB

3.5 nsMeasured

Pulse

170m

V

-41.3 dBm/MHz

-90

-70

-50

-30

-10

11pJ /pulse

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 59 of number of slides

Table of Comparison

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 60 of number of slides

Table of Comparison

HighestFOM and Input DR Among Active

Electrode Systems

And Traditional

AFEs

Paper Number: Paper Title© 2019 IEEE International Solid-State Circuits Conference 61 of number of slides

Conclusion1. Motivation

Increase Battery Life and Reduce Wiring Clutter for High Fidelity/Density EEG

2. ApproachA Scalable Multi-Channel FM-FDM Sensor NetworkIntegrated Gateway with ADC and UWB TX

3. ResultsRuggedLow PowerResilient to Motion

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