Design and Analysis of A Dual-Band Bistatic Backscatter Circuit for Passive RFID Tags

Passive radio-frequency identification (RFID) tags, when placed remotely or in harsh environments, will benefit the most if the communication distance between the tag and reader is vastly improved. The bistatic backscattering technique provides a solution to this problem by separating the carrier and backscattered signal in frequency, which helps mitigate interference. It also decouples the reader from carrier generation by having a separate radio-frequency (RF) emitter and further improves the signal strength by reducing round trip path loss. A dual-band on-chip bistatic backscattering circuit design for passive RFID tags is presented in this paper using a 180 nm CMOS process dissipating 35 $\mu \mathrm{W}$ of power. Post layout simulation results provide a communicable distance of 170 m between the tag and reader at 868 MHz and 60 m at 2.4 GHz when the tag is kept 5 m away from the RF emitter.