volume | PIER Journals

Abstract

Just over a decade ago, wireless capsule endoscopy (WCE) was introduced as a novel alternative to conventional wire or probe endoscopy to examine disorders of the human gastrointestinal (GI) tract. Yet, the persistent inability of transmitting high-quality images due to limited data rate of the telemetry system continues to be an issue of major concern. Thus, high-data-rate telemetry systems are essential due to the widespread use of the WCE technique. In this paper, we present such a telemetry system that includes a highly-simplified receiver for the use in WCE. Unlike the conventional architecture of a radio frequency (RF) receiver, the architecture of the new receiver allows the direct conversion of analog RF signals to digital signals, eliminating the need for any frequency conversion in the analogue domain. Our receiver system consists of sub-blocks, a low-noise amplifier (LNA), a logarithmic amplifier (LA), a power detector (PD), and a comparator. The common-source cascode LNA was designed with its frequency spectrum centralized at 450 MHz, which was determined by electromagnetic (EM) simulation of the path loss in the GI tract of the human body. To ensure that the higher data rate, i.e., 100 Mbps, could be attained, the LNA was designed for a system bandwidth of 100 MHz, i.e., 400-500 MHz. The LNA and the three cascading blocks in combination have total gain of 80 dB to compensate for the losses in the weak signals that are received. The LNA and the LA, including the PD and the comparator, require 17-mA and 337-μA currents, respectively, from a 1.5-V, DC source.

1. Iddan, G., G. Moron, A. Glukhovsky, and P. Swain, "Wireless capsule endoscopy," Nature, Vol. 405, 417, May 2000.
doi:10.1038/35013140 Google Scholar

2. Basar, M. R., F. Malek, K. M. Juni, M. S. Idris, and M. I. M. Saleh, "Ingestible wireless capsule technology: A review of development and future indication," International Journal of Antenna and Propagation, Vol. 2012, 1-14, 2012.
doi:10.1155/2012/807165 Google Scholar

3. Pan, G. and L. Wang, "Swallowable wireless capsule endoscopy: Progress and technical challenges," Gastroenterology Research and Practice, Vol. 2012, 1-9, 2011.
doi:10.1155/2012/841691 Google Scholar

4. Ciuti, G., A. Menciassi, and P. Dario, "Capsule endoscopy: From current achievements to open challenges," IEEE Reviews in Biomedical Engineering, Vol. 4, 59-72, 2011.
doi:10.1109/RBME.2011.2171182 Google Scholar

5. Chi, B., J. Yao, S. Han, X. Xie, G. Li, and Z. Wang, "Low power high data rate wireless endoscopy transceiver," Microelectronics Journal, Vol. 38, 1070-1081, 2007.
doi:10.1016/j.mejo.2007.07.118 Google Scholar

6. Thoné, J., S. Radiom, D. Turgis, R. Carta, G. Gielen, and R. Puers, "Design of a 2 Mbps FSK near-field transmitter for wireless capsule endoscopy," Sensors and Actuators A: Physical, Vol. 156, 43-48, 2009.
doi:10.1016/j.sna.2008.11.027 Google Scholar

7. Diao, S., Y. Zheng, and C. Heng, "A CMOS ultra low-power and highly e±cient UWB-IR transmitter for WPAN applications," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 56, 200-204, 2009.
doi:10.1109/TCSII.2009.2015369 Google Scholar

8. Gao, Y., Y. Zheng, S. Diao, W. Toh, C. Ang, M. Je, and C. Heng, "Low-power ultrawideband wireless telemetry transceiver for medical sensor applications," IEEE Transactions on Biomedical Engineering, Vol. 58, 768-772, 2011.
doi:10.1109/TBME.2011.2164248 Google Scholar

9. Wong, S.-K., F. Kung, S. Maisurah, and M. N. B. Osman, "A WiMedia compliant CMOS RF power amplifier for ultra-wideband (UWB) transmitter," Progress In Electromagnetics Research, Vol. 112, 329-347, 2011. Google Scholar

10. Basar, M. R., F. Malek, K. M. Juni, M. I. M. Saleh, M. S. Idris, L. Mohamed, N. Saudin, N. A. Mohd Affendi, and A. Ali, "The use of a human body model to determine the variation of path losses in the human body channel in wireless capsule endoscopy," Progress In Electromagnetics Research, Vol. 133, 495-513, 2013. Google Scholar

11. Theilmann, P., M. A. Tassoudji, E. H. Teague, D. F. Kimball, and P. M. Asbeck, "Computationally efficient model for UWB signal attenuation due to propagation in tissue for biomedical implants," Progress In Electromagnetics Research B, Vol. 38, 1-22, 2012. Google Scholar

12. Kim, K., S. Yun, S. Lee, S. Nam, Y. Yoon, and C. Cheon, "A design of a high-speed and high-e±ciency capsule endoscopy system," IEEE Transactions on Biomedical Engineering, Vol. 59, 1005-1011, Apr. 2012.
doi:10.1109/TBME.2011.2182050 Google Scholar

13. Woo, S. H., K. W. Yoon, Y. K. Moon, J. H. Lee, H. J. Park, T. W. Kim, et al. "High speed receiver for capsule endoscope," Journal of Medical Systems, Vol. 34, 843-847, 2010.
doi:10.1007/s10916-009-9298-1 Google Scholar

14. Basar, M. R., M. F. B. A. Malek, M. I. M. Saleh, M. S. Idris, K. M. Juni, A. Ali, N. A. Mohd Affendi, and N. Hussin, "A novel, high-speed image transmitter for wireless capsule endoscopy," Progress In Electromagnetics Research, Vol. 137, 129-147, 2013. Google Scholar

15. Gabriel, C., S. Gabriel, and E. Corthout, "The dielectric properties of biological tissues: I. Literature survey," Physics in Medicine and Biology, Vol. 41, 2231-2249, 1996.
doi:10.1088/0031-9155/41/11/001 Google Scholar

16. Chen, Z. and Y. P. Zhang, "Effects of antennas and propagation channels on synchronization performance of a pulse-based ultra-wideband radio system," Progress In Electromagnetics Research, Vol. 115, 95-112, 2011. Google Scholar

17. Gjonaj, E., M. Bartsch, M. Clemens, S. Schupp, and T. Weiland, "High-resolution human anatomy models for advanced electromagnetic field computations," IEEE Transactions on Magnetics, Vol. 38, No. 2, 357-360, Mar. 2002.
doi:10.1109/20.996096 Google Scholar

18. Carlson, B., B. C. Paul, and C. R. Janet, Communication Systems --- An Introduction to Signals and Noise in Electrical Communications, 4th Ed., McGraw-Hill, 2001.

19. Carmo, J. P. and J. H. Correia, "RF CMOS transceiver at 2.4 GHz in wearables for measuring the cardio-respiratory function," Measurement, Vol. 44, 65-73, 2011.
doi:10.1016/j.measurement.2010.09.027 Google Scholar

20. Ellinger, F., Radio Frequency Integrated Circuits and Technologies, Springer-Verlag, Berlin, Heidelberg, 2007.

21. Shaeffer, D. and T. Lee, "A 1.5 V, 1.5 GHz CMOS low-noise amplifier," IEEE Journal of Solid-State Circuits, Vol. 39, 569-576, 2004. Google Scholar

22. Doh, H., Y. Jeong, S. Jung, and Y. Joo, "Design of CMOS UWB low noise amplifier with cascade feedback," The 7th IEEE International Midwest Symposium on Circuits and Systems, 641-644, 2004.

23. Rubin, S. N., "A wideband UHF logarithmic amplifier," IEEE Journal of Solid-State Circuits, Vol. 2, 74-81, 1966.
doi:10.1109/JSSC.1966.1049762 Google Scholar

24. Barber, W. L. and E. R. Brown, "A true logarithmic amplifier for radar IF applications," IEEE Journal of Solid-State Circuits, Vol. 15, 291-295, 1980.
doi:10.1109/JSSC.1980.1051386 Google Scholar

Dr. Md. Rubel Basar

Dr. Mohd Fareq Bin Abd Malek

Dr. Khairudi Mohd Juni

Dr. Mohd Shaharom Idris

Dr. Mohd Iskandar Mohd Saleh