Powering of single-chip fully integrated RFID wireless sensors

In this paper we present some guidelines for the design of single-chip RFID sensors, focusing in the powering aspects of these wireless systems. The methodology and key aspects for the optimization of the powering coil and the integrated inductor based on finite element analysis simulations and lumped-element models, correspondingly, is described. Simulation results are shown for an example of design, and compared with measurements of a real coil fabricated with a 0.18 μm CMOS technology. Parameters obtained by simulation and by measurement are in good agreement. With this example we show that a wireless sensor in a 1.5 × 1.5 mm
²
chip with a consumption of 400 μA at 1.8 V could be powered at a distance of 4.4 mm with a 1.2 cm powering coil connected to a 250 mW RF amplifier working at 13.56 MHz.