LTE-Powered BLE-to-WiFi Backscattering Chip Toward Single-Device Interrogation RFID-Like Systems

This letter presents a backscattering chip that is powered via LTE signals and reflects an incident reverse-whitened Bluetooth low energy (BLE) tone-like advertisement packet into a reradiated single-side-band (SSB) 802.11 b WiFi packet at a configurable WiFi channel location, all toward enabling an RFID-like single-device interrogation system. The chip includes an RF energy harvester, a WiFi wake-up receiver, an intermediate frequency (IF) ring oscillator whose frequency is calibrated with a successive-approximation-register (SAR) frequency-lock-loop (FLL), and a QPSK SSB backscatter modulator. Implemented in 65-nm CMOS, the chip consumes 4.5- $\mu \text{W}$ power in wake-up mode and 11 to $45~\mu \text{W}$ power in backscatter mode, with on-chip ring oscillator frequencies ranging from 33 to 253 MHz in order to support eight different BLE-to-WiFi backscatter schemes. Wireless measurement showed that the chip can be charged to 1 V before backscattering within 1 s on a 1- $\mu \text{F}$ off-chip storage capacitor up to a 50-cm distance.