Tunneling RFID Tags for Long-Range and Low-Power Microwave Applications

Backscatter modulation in radio frequency identification (RFID) tags will potentially connect billions of tomorrow’s devices to the Internet-of-Things. Current passive RFID systems have power constraints that limit RFID tag communication to short ranges, but these limitations can be overcome by employing reflection amplifiers. In this paper, we show that negative differential resistance devices, such as tunnel diodes, exhibit 27 dB more gain and 10 dB lower power consumption than state-of-the-art reflection amplifiers. Two 5.8 GHz prototypes using off-the-shelf tunnel diodes show reflection gains of 40 dB and 29 dB for a total biasing power consumption of 45 <inline-formula> <tex-math notation="LaTeX">${\mu }\text{W}$ </tex-math></inline-formula> and 39 <inline-formula> <tex-math notation="LaTeX">${\mu }\text{W}$ </tex-math></inline-formula>, respectively, at impinging RF power levels as low as −84 dBm. A 5.8 GHz RFID link of 23 m was achieved when transmitting only −14 dBm of effective isotropic radiated power from a transceiver with a sensitivity of −90 dBm.