A wideband frequency-shift keying wireless link for inductively powered biomedical implants

A high data-rate frequency-shift keying (FSK) modulation protocol, a wideband inductive link, and three demodulator circuits have been developed with a data-rate-to-carrier-frequency ratio of up to 67%. The primary application of this novel FSK modulation/demodulation technique is to send data to inductively powered wireless biomedical implants at data rates in excess of 1 Mbps, using comparable carrier frequencies. This method can also be used in other applications such as radio-frequency identification tags and contactless smartcards by adding a back telemetry link. The inductive link utilizes a series-parallel inductive-capacitance tank combination on the transmitter side to provide more than 5 MHz of bandwidth. The demodulator circuits detect data bits by directly measuring the duration of each received FSK carrier cycle, as well as derive a constant frequency clock, which is used to sample the data bits. One of the demodulator circuits, digital FSK, occupies 0.29 mm/sup 2/ in the AMI 1.5-/spl mu/m, 2M/2P, standard CMOS process, and consumes 0.38 mW at 5 V. This circuit is simulated up to 4 Mbps, and experimentally tested up to 2.5 Mbps with a bit error rate of 10/sup -5/, while receiving a 5/10-MHz FSK carrier signal. It is also used in a wireless implantable neural microstimulation system.

[1]  R.A. Normann,et al.  An advanced demultiplexing system for physiological stimulation , 1997, IEEE Transactions on Biomedical Engineering.

[2]  Gerald E. Loeb,et al.  Development of BION/spl trade/ technology for functional electrical stimulation: bidirectional telemetry , 2001, 2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[3]  J.A. Von Arx,et al.  On-chip coils with integrated cores for remote inductive powering of integrated microsystems , 1997, Proceedings of International Solid State Sensors and Actuators Conference (Transducers '97).

[4]  Maysam Ghovanloo,et al.  A high-rate frequency shift keying demodulator chip for wireless biomedical implants , 2003, Proceedings of the 2003 International Symposium on Circuits and Systems, 2003. ISCAS '03..

[5]  Glenn A. DeMichele,et al.  Inductively-coupled power and data link for neural prostheses using a class-E oscillator and FSK modulation , 2003, Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439).

[6]  Khalil Najafi,et al.  A fully digital frequency shift keying demodulator chip for wireless biomedical implants , 2003, Southwest Symposium on Mixed-Signal Design, 2003..

[7]  P.R. Troyk,et al.  Inductive links and drivers for remotely-powered telemetry systems , 2000, IEEE Antennas and Propagation Society International Symposium. Transmitting Waves of Progress to the Next Millennium. 2000 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (C.

[8]  Tim Collins,et al.  Secure contactless smartcard ASIC with DPA protection , 2001 .

[9]  Tim Collins,et al.  Secure contactless smartcard ASIC with DPA protection , 2000, Proceedings of the IEEE 2000 Custom Integrated Circuits Conference (Cat. No.00CH37044).

[10]  Pascal Vivet,et al.  A new contactless smart card IC using an on-chip antenna and an asynchronous microcontroller , 2001 .

[11]  R. White,et al.  A Wide-Band Efficient Inductive Transdennal Power and Data Link with Coupling Insensitive Gain , 1987, IEEE Transactions on Biomedical Engineering.

[12]  M. Ghovanloo,et al.  Fully integrated wideband high-current rectifiers for inductively powered devices , 2004, IEEE Journal of Solid-State Circuits.

[13]  Khalil Najafi,et al.  A BiCMOS wireless stimulator chip for micromachined stimulating microprobes [neural recording/prostheses application] , 2002, Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology.

[14]  Charles Polk,et al.  CRC Handbook of Biological Effects of Electromagnetic Fields , 1986 .

[15]  Khalil Najafi,et al.  A high data transfer rate frequency shift keying demodulator chip for the wireless biomedical implants , 2002, The 2002 45th Midwest Symposium on Circuits and Systems, 2002. MWSCAS-2002..

[16]  W. Liu,et al.  A neuro-stimulus chip with telemetry unit for retinal prosthetic device , 2000, IEEE Journal of Solid-State Circuits.

[17]  C.M. Zierhofer,et al.  High-efficiency coupling-insensitive transcutaneous power and data transmission via an inductive link , 1990, IEEE Transactions on Biomedical Engineering.

[18]  J. Weiland,et al.  Retinal prosthesis for the blind. , 2002, Survey of ophthalmology.

[19]  Khalil Najafi,et al.  Towards a button-sized 1024-site wireless cortical microstimulating array , 2003 .

[20]  P. R. Troyk,et al.  DEVELOPMENT OF BION TECHNOLOGY FOR FUNCTIONAL ELECTRICAL STIMULATION : BIDIRECTIONAL TELEMETRY , 2001 .

[21]  Ma Lin,et al.  A deductive method for antenna near-field computation in EMC prediction , 2004, Proceedings. ICCEA 2004. 2004 3rd International Conference on Computational Electromagnetics and Its Applications, 2004..

[22]  Richard A. Normann,et al.  Simulation of a phosphene-based visual field: Visual acuity in a pixelized vision system , 2006, Annals of Biomedical Engineering.

[23]  Gary M Miller,et al.  Modern Electronic Communication , 1978 .

[24]  W.J. Heetderks,et al.  RF powering of millimeter- and submillimeter-sized neural prosthetic implants , 1988, IEEE Transactions on Biomedical Engineering.

[25]  Khalil Najafi,et al.  A BiCMOS wireless interface chip for micromachined stimulating microprobes , 2002, 2nd Annual International IEEE-EMBS Special Topic Conference on Microtechnologies in Medicine and Biology. Proceedings (Cat. No.02EX578).

[26]  K. Najafi,et al.  A Modular 32-site wireless neural stimulation microsystem , 2004, IEEE Journal of Solid-State Circuits.

[27]  C. Zierhofer,et al.  Electronic design of a cochlear implant for multichannel high-rate pulsatile stimulation strategies , 1995 .

[28]  Daryl R. Kipke,et al.  Wireless implantable microsystems: high-density electronic interfaces to the nervous system , 2004, Proceedings of the IEEE.

[29]  Nigel H. Lovell,et al.  CMOS neurostimulation ASIC with 100 channels, scaleable output, and bidirectional radio-frequency telemetry , 2001, IEEE Transactions on Biomedical Engineering.

[30]  W. Ko,et al.  Design of radio-frequency powered coils for implant instruments , 1977, Medical and Biological Engineering and Computing.

[31]  C.M. Zierhofer,et al.  Geometric approach for coupling enhancement of magnetically coupled coils , 1996, IEEE Transactions on Biomedical Engineering.