A Bidirectional Neural Interface IC With Chopper Stabilized BioADC Array and Charge Balanced Stimulator

We present a bidirectional neural interface with a 4-channel biopotential analog-to-digital converter (bioADC) and a 4-channel current-mode stimulator in 180 nm CMOS. The bioADC directly transduces microvolt biopotentials into a digital representation without a voltage-amplification stage. Each bioADC channel comprises a continuous-time first-order ΔΣ modulator with a chopper-stabilized OTA input and current feedback, followed by a second-order comb-filter decimator with programmable oversampling ratio. Each stimulator channel contains two independent digital-to-analog converters for anodic and cathodic current generation. A shared calibration circuit matches the amplitude of the anodic and cathodic currents for charge balancing. Powered from a 1.5 V supply, the analog and digital circuits in each recording channel draw on average 1.54 μA and 2.13 μA of supply current, respectively. The bioADCs achieve an SNR of 58 dB and a SFDR of >70 dB, for better than 9-b ENOB. Intracranial EEG recordings from an anesthetized rat are shown and compared to simultaneous recordings from a commercial reference system to validate performance in-vivo. Additionally, we demonstrate bidirectional operation by recording cardiac modulation induced through vagus nerve stimulation, and closed-loop control of cardiac rhythm. The micropower operation, direct digital readout, and integration of electrical stimulation circuits make this interface ideally suited for closed-loop neuromodulation applications.

[1]  Anantha Chandrakasan,et al.  An 8-Channel Scalable EEG Acquisition SoC With Patient-Specific Seizure Classification and Recording Processor , 2013, IEEE Journal of Solid-State Circuits.

[2]  Gert Cauwenberghs,et al.  A CMOS Current Steering Neurostimulation Array With Integrated DAC Calibration and Charge Balancing , 2017, IEEE Transactions on Biomedical Circuits and Systems.

[3]  Qiuting Huang,et al.  A fully integrated, untrimmed CMOS instrumentation amplifier with submicrovolt offset , 1999 .

[4]  Jan M. Rabaey,et al.  A Minimally Invasive 64-Channel Wireless μECoG Implant , 2015, IEEE Journal of Solid-State Circuits.

[5]  Gert Cauwenberghs,et al.  Micropower integrated bioamplifier and auto-ranging ADC for wireless and implantable medical instrumentation , 2010, 2010 Proceedings of ESSCIRC.

[6]  M. Morrell.  Responsive cortical stimulation for the treatment of medically intractable partial epilepsy , 2011, Neurology.

[7]  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.

[8]  David Guiraud,et al.  Model-Based Design and Experimental Validation of Control Modules for Neuromodulation Devices , 2016, IEEE Transactions on Biomedical Engineering.

[9]  Fan Zhang,et al.  A Batteryless 19 $\mu$W MICS/ISM-Band Energy Harvesting Body Sensor Node SoC for ExG Applications , 2013, IEEE Journal of Solid-State Circuits.

[10]  G. Y. Fridman,et al.  Design and performance of a multichannel vestibular prosthesis that restores semicircular canal sensation in rhesus monkey , 2011, IEEE Transactions on Neural Systems and Rehabilitation Engineering.

[11]  Peng Cong,et al.  Design and Validation of a Fully Implantable, Chronic, Closed-Loop Neuromodulation Device With Concurrent Sensing and Stimulation , 2012, IEEE Transactions on Neural Systems and Rehabilitation Engineering.

[12]  Rahul Sarpeshkar,et al.  A Low-Power 32-Channel Digitally Programmable Neural Recording Integrated Circuit , 2011, IEEE Transactions on Biomedical Circuits and Systems.

[13]  Refet Firat Yazicioglu,et al.  A 345 µW Multi-Sensor Biomedical SoC With Bio-Impedance, 3-Channel ECG, Motion Artifact Reduction, and Integrated DSP , 2015, IEEE Journal of Solid-State Circuits.

[14]  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.

[15]  Robert G. Meyer,et al.  Analysis and Design of Analog Integrated Circuits , 1993 .

[16]  G. Scandurra,et al.  R-/spl beta/R ladder networks for the design of high-accuracy static analog memories , 2003 .

[17]  Emery N Brown,et al.  A neurophysiological–metabolic model for burst suppression , 2012, Proceedings of the National Academy of Sciences.

[18]  Gabor C. Temes,et al.  Understanding Delta-Sigma Data Converters , 2004 .

[19]  Mohsen Mollazadeh,et al.  Micropower CMOS Integrated Low-Noise Amplification, Filtering, and Digitization of Multimodal Neuropotentials , 2009, IEEE Transactions on Biomedical Circuits and Systems.

[20]  Felice Sun,et al.  Building a bionic nervous system , 2015, IEEE Spectrum.

[21]  Refet Firat Yazicioglu,et al.  A 200 $\mu$ W Eight-Channel EEG Acquisition ASIC for Ambulatory EEG Systems , 2008, IEEE Journal of Solid-State Circuits.

[22]  Rahul Sarpeshkar,et al.  A Low-Power Blocking-Capacitor-Free Charge-Balanced Electrode-Stimulator Chip With Less Than 6 nA DC Error for 1-mA Full-Scale Stimulation , 2007, IEEE Transactions on Biomedical Circuits and Systems.

[23]  Karim Abdelhalim,et al.  64-Channel UWB Wireless Neural Vector Analyzer SOC With a Closed-Loop Phase Synchrony-Triggered Neurostimulator , 2013, IEEE Journal of Solid-State Circuits.

[24]  Ken Yoshida,et al.  Closed-loop control of the heart rate by electrical stimulation of the vagus nerve , 2006, Medical and Biological Engineering and Computing.

[25]  Teresa H. Y. Meng,et al.  HermesE: A 96-Channel Full Data Rate Direct Neural Interface in 0.13 $\mu$ m CMOS , 2012, IEEE Journal of Solid-State Circuits.

[26]  Michael P. Flynn,et al.  A Fully Self-Contained Logarithmic Closed-Loop Deep Brain Stimulation SoC With Wireless Telemetry and Wireless Power Management , 2014, IEEE Journal of Solid-State Circuits.

[27]  A. Rosenblueth,et al.  THE INTERRELATIONS OF VAGAL AND ACCELERATOR EFFECTS ON THE CARDIAC RATE , 1934 .

[28]  G. Cauwenberghs.  Blind on-line digital calibration of multi-stage Nyquist-rate and oversampled A/D converters , 1998, ISCAS '98. Proceedings of the 1998 IEEE International Symposium on Circuits and Systems (Cat. No.98CH36187).

[29]  Kofi A. A. Makinwa,et al.  A 1.8 $\mu$ W 60 nV$/\surd$ Hz Capacitively-Coupled Chopper Instrumentation Amplifier in 65 nm CMOS for Wireless Sensor Nodes , 2011, IEEE Journal of Solid-State Circuits.

[30]  S. Haber,et al.  Closed-Loop Deep Brain Stimulation Is Superior in Ameliorating Parkinsonism , 2011, Neuron.

[31]  Tobi Delbrück,et al.  32-bit Configurable bias current generator with sub-off-current capability , 2010, Proceedings of 2010 IEEE International Symposium on Circuits and Systems.

[32]  F. O. Eynde,et al.  A high-speed CMOS comparator with 8-b resolution , 1992 .

[33]  Nitish V. Thakor,et al.  Flexible Charge Balanced Stimulator With 5.6 fC Accuracy for 140 nC Injections , 2013, IEEE Transactions on Biomedical Circuits and Systems.

[34]  Mohsen Mollazadeh,et al.  A 5 μW/channel 9b-ENOB BioADC array for electrocortical recording , 2015, 2015 IEEE Biomedical Circuits and Systems Conference (BioCAS).

[35]  R. Schreier,et al.  Delta-sigma modulators employing continuous-time circuitry , 1996 .

[36]  Ralph Etienne-Cummings,et al.  A closed-loop compressive-sensing-based neural recording system , 2015, Journal of neural engineering.

[37]  A.-T. Avestruz,et al.  A 5 $\mu$ W/Channel Spectral Analysis IC for Chronic Bidirectional Brain–Machine Interfaces , 2008, IEEE Journal of Solid-State Circuits.