The Harmonic Tunneling Tag: a Dual-Band Approach to Backscattering Communications

As an answer to the self-interference problem inherent to RFID systems, this work proposes a dual-band backscattering architecture. A dual-band RFID system architecture can bring several advantages to the RFID technology. In fact, a dual-band reader could operate without any self-interference cancellation circuit that currently limits its sensitivity; moreover, its dual-band architecture would be compatible with software defined radio-based cellphones. Dual-band readers will need to talk with low-powered dual-band tags that up-convert, modulate, and backscatter the impinging signal from the fundamental frequency to the 2
^nd
harmonic without weakening the communication link. This article reports on the UHF dual-band Harmonic Tunneling Tag capable of backscattering and amplifying a 900 MHz signal when receiving an input carrier at 450 MHz. The Harmonic Tunneling Tag provides positive conversion gains (+7 dB) that improve the communication link by a factor of 2 and operates under a very low bias voltage of 0.16 V.