RFID Circuit Design with Optimized CMOS Inductor for Monitoring Biomedical Signals

RFID is evolving as a major technology enabler for identifying and tracking goods. RFID applications in biomedical area not only need to detect but also require monitoring and transmitting vital signals like the electrocardiogram (and heartbeat), blood pressure, body temperature, etc. The basic building blocks of an RFID tag for biomedical application are studied. The sizing and powering up of the tags are critical issues and this paper mainly focuses on the design and optimization of the inductor for an RFID circuit. UHF is chosen for this application mainly because of the practical values of inductance that can be realized in CMOS chip to operate at this operating frequency. The layout parameters of inductor are optimized for a maximum Q-factor value at the desired frequency. Using the optimized inductor, the functioning of the important blocks of an RFID tag such as power feeding circuit, heartbeat detection circuit as well as the modulation circuit is verified. This work would be very relevant for the remote monitoring of biomedical signals.