2-D Smart Surface Object Localization by Flexible 160-nW Monolithic Capacitively Coupled 12-b Identification Tags Based on Metal–Oxide TFTs

Among the diverse and ever-expanding list of candidate technologies to serve the Internet of Everything, the rise of thin-film transistors on plastic as active components for ubiquitous ICs has been nothing short of meteoric. The stage for this explosion of interest was set by a pivotal advantage of the low manufacturing cost and ultrathin form factor, as demonstrated in recent prototypes of thin-film radio frequency identification (RFID) tags. Most RFID tags use inductive antennas, whereas, in this paper, capacitively coupled antenna is presented. Advantages of capacitive-coupled tags are the monolithic integrated antenna, the compact size, the additional security due to very short range of operation, and the localization and orientation abilities. The main circuit block of the tag, a 12-bit code generator, is demonstrated achieving only 160 nW of power dissipation at 0.3 V power supply transmitting data at 810 b/s on a 18 $\mu \text{m}$ -thick plastic substrate. The footprint of the monolithic integrated antenna is 1 cm 2 and essentially defines the size of the full tag.