Document Type : Full Research Paper

Authors

1 MSc. Graduated, School of Electrical and Computer Engineering, College of Engineering, University of Tehran

2 Assistant Professor, School of Electrical and Computer Engineering, College of Engineering, University of Tehran

3 PhD Candidate, School of Electrical and Computer Engineering, College of Engineering, University of Tehran - Instructor, Collage of Electrical Engineering, Urmia University of Technology

10.22041/ijbme.2014.13554

Abstract

Currently need for ultra low power wireless transmitters in medical applications are inevitable. In this paper a new transmitter for body-worn and implantable sensor nodes is presented. Most of the sensor nodes supply their power using energy harvesting instead of a battery, since the power earned by harvesting is limited, so the average and the peak power consumption of the sensor node must be minimized. Transmitter blocks which implemented in sensor nodes are too power consuming. So a new low power Binary Frequency Shift Keying (BFSK) transmitter based on sub-harmonic current mode injection locking, and edge combining technique has been proposed. The proposed transmitter was designed to make a mutual communication between sensor node and base station, so there is no need for complexity at receiver side. In order to reduce the consuming power at transmitter side, BFSK modulation is done at reference frequency to prevent usage of power consuming low phase noise oscillator at carrier frequency. A 34MHz reference clock is used and the frequency of reference clock multiplied by 12 for desired carrier frequency. The phase noise of the carrier at 1MHz frequency offset is -117 dBc/Hz. Total power consumption of the transmitter is about 144μW. The output carrier frequency is 408MHz. BFSK modulation scheme is used at the frequency much lower than the carrier frequency in order to reduce the power consumption.

Keywords

[1]   Thomas, S. J.; Harrison, R. R.; Leonardo, A.; Reynolds, M. S.; ,ABattery-Free Multichannel Digital Neural/EMG Telemetry System for Flying Insects," Biomedical Circuits and Systems, IEEE Transactions on , vol.6, no.5, pp.424-436, Oct. 2012
[2]   Yeager, D.; Fan Zhang; Zarrasvand, A.; George, N.T.; Daniel, T.; Otis, B.P.; , "A 9   A, Addressable Gen2 Sensor Tag for Biosignal Acquisition," Solid-State Circuits, IEEE Journal of , vol.45, no.10, pp.2198-2209, Oct. 2010
[3]    Harrison, R.R.; Kier, R.J.; Leonardo, A.; Fotowat, H.; Chan, R.; Gabbiani, F.; , "A wireless neural/EMG telemetry system for freely moving insects," Circuits and Systems (ISCAS), Proceedings of 2010 IEEE International Symposium on , vol., no., pp.2940-2943, May 30 2010-June 2 2010
[4]   Jeremy Holleman ,Fang Zhang ,Brian Otis ,“Ultra Low-Power Integrated Circuit Design for Wireless Neural Interface,” Springer, 2011
[5]   Behzad Razavi, “RF Microelectronics,”2nd edition, Prentice Hall, 2012
[6]   Joonsung Bae; Long Yan; Hoi-Jun Yoo; , "A Low Energy Injection-Locked FSK Transceiver With Frequency-to-Amplitude Conversion for Body Sensor Applications," Solid-State Circuits, IEEE Journal of , vol.46, no.4, pp.928-937, April 2011
[7]   J. Pandey, B. P. Otis A“ Sub-100 W MICS/ISM Band Transmitter Based on Injection-Locking and Frequency Multiplication,” IEEE J. Solid-State Circuits , vol. 46, no. 5, May 2011
[8]   Takano, K.; Motoyoshi, M.; Fujishima, M., "4.8GHz CMOS frequency multiplier with subharmonic pulse-injection locking," Solid-State Circuits Conference, 2007. ASSCC '07. IEEE Asian , vol., no., pp.336,339, 12-14 Nov. 2007
[9]     Xiaolue Lai; Roychowdhury, J., "Analytical equations for predicting injection locking in LC and ring oscillators," Custom Integrated Circuits Conference, 2005. Proceedings of the IEEE 2005 , vol., no., pp.461,464, 18-21 Sept. 2005
[10]   T. Sakurai and R. Newton, “Alpha-power law MOSFET model andits applications to CMOS inverter delay and other formulas,” IEEE J.Solid-State Circuits, vol. 25, no. 2, pp. 584–594, Apr. 1990.
[11]   B. Otis, Ultra-low power wireless technologies for sensor  networks. Ph. D. thesis, University of California, Berkeley, Apr 2005
[12]   J. Bohorquez, A. Chandrakasan, and J. Dawson, “A 350 W CMOSMSK    transmitter and 400 W OOK super regenerative receiver for medical implant communications,” IEEE J. Solid-State Circuits, vol.44, no. 4, pp. 1248–1259, Apr. 2009.
[13 ]  S. Rai, J. Holleman, J. Pandey, F. Zhang, and B. Otis, “A 500 W neural tag with 2 AFE and frequency-multiplying MICS/ISM FSK transmitter,” in IEEE Int. Solid-State Circuits Conf. (ISSCC) Dig Tech. Papers, 2009.
[14]    Yao-Hong Liu; Tsung-Hsien Lin, "A Wideband      PLL-Based G/FSK Transmitter in 0.18 µm CMOS,"  Solid-State Circuits, IEEE Journal of , vol.44, no.9, pp.2452,2462, Sept. 2009  
[15]   Masuch, J.; Delgado-Restituto, M., "A Sub-10  nJ/b 1.9-dBm Output Power FSK Transmitter for Body Area Network Applications," Microwave Theory and Techniques, IEEE Transactions on , vol.60, no.5, pp.1413,1423, May 2012
[16]   Zhiming Chen; Kuang-Wei Cheng; Yuanjin Zheng; Minkyu Je, "A 3.4-mW 54.24-Mbps burst-mode injection-locked CMOS FSK transmitter," Solid State Circuits Conference (A-SSCC), 2011 IEEE Asian , vol., no., pp.289,292, 14-16 Nov. 2011
  [17]  Jri Lee; Wang, Huaide, "Study of Subharmonically Injection-Locked PLLs," Solid-State Circuits, IEEE Journal of , vol.44, no.5, pp.1539,1553, May 2009
[18]         Vittoz, E.A.; Degrauwe, M.G.R.; Bitz, S., "High-performance crystal oscillator circuits: theory and application," Solid-State Circuits, IEEE Journal of , vol.23, no.3, pp.774,783, June 1988