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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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