An Efficient RF Rectifier for Energy Harvesting Systems with Applications to Wireless Dosimetry

Abstract

In the medical industry, there exists a great need for donated blood, which must first be sterilized before being used in transfusions. A growing number of facilities have begun to use X-ray irradiation for blood sterilization, along with a tag employing a radiation-sensitive chemical to measure the applied dose. Such an approach is prone to measurement error and inaccuracy, leading to the wastage of blood, time, and expense. A wireless RFID sensor tag has been proposed by researchers at Carleton University. This work presents both a system-level overview of the X-ray dosimeter tag and a design of the energy harvesting module.The wireless X-ray dosimeter tag is estimated to consume 263.1 µW of power and is designed to operate at a distance of one metre away from a 2.45 GHz intentional RF power source. This source is harnessed by the energy harvesting module, which consists of a: dipole antenna, matching network, Dynamic V th Cancellation (DVC) rectifier, Smart Voltage Regulator (SVR), and off-chip ceramic capacitor.As part of the energy harvesting module, an RF rectifier employing DVC was designed and implemented in a commercial 0.13 µm CMOS process. Experimental measurements demonstrate that the design achieves a peak power conversion efficiency (PCE) of 49.7% at a power level of -12.0 dBm, an operational frequency of 2.45 GHz, and an output loading of 25 kΩ.ii This thesis is dedicated to my parents, for whose love and support has made this journey possible, and to the enduring memory of my grandparents.iii Acknowledgments I would first like to extend my foremost gratitude to my thesis supervisor, Professor Langis Roy, in recognition of his extraordinary commitment to my work. I am truly grateful for the countless hours of consultation he provided.In addition, I would like to express my sincere appreciation for several individuals

Development of a 2.45 GHz Antenna for Flexible Compact Radiation Dosimeter Tags

“…The 2.45 GHz dosimeter will be used in a semi-passive RFID tag employing backscatter modulation and wireless power transfer to ensure minimal power consumption and low-form factor. It comprises an energy harvesting unit -the proposed antenna, rectifier and off-chip capacitor -for self-powered operation, an FG-MOSFET which senses the received radiation dosage, signal processing electronics that convert measured data to pulses and a transmitter or modulator that sends the pulses to a reader operating in the same frequency band [22]. Similar to the RadTag labels, the proposed dosimeter tags are to be applied to the blood bags as depicted in Fig.…”

“…Typically, the RFID tag has a data transfer rate of 100 kilobits-per-second (kbps) where the ID value, measured radiation dose and temperature are each represented by 16-bit values. [22] The key requirements in this application are low-form factor, conformity of the dosimeter tag, efficient antenna performance on lossy host structure (blood products), and adequate wireless power transfer operation when implemented in a rectenna configuration. The tags are to communicate with RF reader at a maximum distance of one meter.…”

Low Power Wireless CMOS System-On-Chip X-Ray Dosimeter

“…A diagrammatic representation of the dosimeter system is illustrated in Figure 2.1 [17]. The system comes with a canister, the volume of which determines the size and the number of the blood bags that can be used.…”

“…A reader, placed inside the Raycell Mk2 R , measures the dosage of the RFID tags through a small opening in the side of the chamber. [17] Although the remaining tags do not communicate with the reader, they still serve a special purpose. Instead of wasting this communication link, the system intelligently uses it for energy harvesting purposes.…”

“…The antenna and tag ID are used by multiple sub-blocks. [17] In order to compare the transmitted ID to the tag's ID, a demodulator, decoder and oscillator blocks are used and are shown in purple. An envelope detector is integrated…”