768 IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, VOL. 58, NO. 3, MARCH 2011 Low-Power Ultrawideband Wireless Telemetry Transceiver for Medical Sensor Applications Yuan Gao*, Member, IEEE, Yuanjin Zheng, Member, IEEE, Shengxi Diao, Wei-Da Toh, Chyuen-Wei Ang, Minkyu Je, Member, IEEE, and Chun-Huat Heng, Member, IEEE Abstract—An integrated CMOS ultrawideband wireless teleme- try transceiver for wearable and implantable medical sensor ap- plications is reported in this letter. This high duty cycled, nonco- herent transceiver supports scalable data rate up to 10 Mb/s with energy efficiency of 0.35 nJ/bit and 6.2 nJ/bit for transmitter and receiver, respectively. A prototype wireless capsule endoscopy using the proposed transceiver demonstrated in vivo image transmission of 640 × 480 resolution at a frame rate of 2.5 frames/s with 10 Mb/s data rate. Index Terms—Telemetry, ultrawideband (UWB), wireless body area network, wireless capsule endoscopy. I. INTRODUCTION T HE application of wireless telemetry in wearable and im- plantable medical sensors is an emerging research area which has attracted significant attention in recent years [1]–[3]. Fig. 1 illustrates a typical wireless telemetry application scenario in personal healthcare. A medical sensor with built-in wire- less transceiver provides a bidirectional data/command teleme- try link with portable personal healthcare server which can be installed in a personal digital assistant or smart phone. The re- ceived vital signals are then forwarded to the doctor through internet for diagnostic and therapeutic purposes. To facilitate more accurate diagnosis, high data rate wireless link up to 10 Mb/s is required for applications like wireless capsule endoscopy or multichannel biosensor signal recording. However, current available medical wireless communication standard such as medical implant communication service [4] only covers from 402–405 MHz with limited 300 kHz channel bandwidth. It can only support data rate up to a few hundred kilobytes per second. Low power consumption is another crit- ical requirement for the transceiver, since the battery capacity is severely constrained by the device size and the sensor is re- Manuscript received July 19, 2010; revised October 4, 2010; accepted November 21, 2010. Date of publication December 6, 2010; date of current version February 18, 2011. This work was supported by the MedTech Research Program, Agency for Science, Technology and Research (A*STAR), Singapore, under Grant 082 140 0033. Asterisk indicates corresponding author. *Y. Gao is with the Institute of Microelectronics, Singapore Science Park II, Singapore 117685 (e-mail: gaoy@ime.a-star.edu.sg). Y. Zheng, S. X. Diao, W.-D. Toh, C.-W. Ang, and M. Je are with the Institute of Microelectronics, Singapore Science Park II, Singapore 117685. C.-H. Heng is with the Department of Electrical and Computer Engineer- ing, National University of Singapore, Singapore 119260 (e-mail: elehch@ nus.edu.sg). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TBME.2010.2097262 Fig. 1. Wireless telemetry system for healthcare applications. quired to support long hour of operation without any battery replacement. Impulse radio-ultrawideband (IR-UWB) communication [5] has been chosen by IEEE 802.15.6 task group as a possible phys- ical layer solution for wireless body area network. It transmits data using a short pulse of a few nanoseconds, which only oc- cupies a small fraction of the symbol period. Exploiting the low duty cycle of IR-UWB signaling, the transceiver can achieve low power operation by turning on only during pulse transmis- sion. Therefore, the transceiver power consumption is scalable with data rate and high energy efficiency can be maintained over a wide range of data rates. In addition, noncoherent energy detection can be employed in the receiver, which eliminates power consuming local oscillator and carrier synchronization blocks. The simplified receiver architecture also leads to further power reduction and faster turn on/off time. Therefore, IR-UWB is regarded as a strong candidate for high data rate wireless telemetry. Recently, IR-UWB system application in biomedi- cal sensor has been reported in the literature [6]. However, the chosen transmitter architecture with passive pulse shaping filter suffers from limited output voltage swing. This constrains the communication range and its usability for implantable device applications. Furthermore, only integrated transmitter but not integrated receiver is reported. In this letter, a fully integrated IR-UWB wireless telemetry transceiver for wearable/implantable medical sensor applica- tions is presented. Transmitter and receiver architectures with high energy efficiencies are proposed to achieve high data rate with low power consumption. The proposed transceiver is ver- ified in a prototype wireless capsule endoscopy with in vivo animal test for image transmission. 0018-9294/$26.00 © 2011 IEEE