Abstract:
This article reports a Bluetooth Low-Energy (BLE) transmitter (TX) tag without the battery and crystal (XTAL) while supporting multitag time-division duplex (TDD) and fre...Show MoreMetadata
Abstract:
This article reports a Bluetooth Low-Energy (BLE) transmitter (TX) tag without the battery and crystal (XTAL) while supporting multitag time-division duplex (TDD) and frequency-division duplex (FDD) broadcasting. Such TX tag has a PCB size of 17 \times 27 \times 3 mm ^{3} , including 1 off-chip antenna and 1 off-chip storage capacitor. It facilitates installation in large-scale deployment in intelligent warehouses, portable devices, or volume-constrained, hard-to-reach locations. The key innovations are threefold: 1) a single antenna that not only features a trifilar RF harvester and an RF-reference phase-locked loop (PLL) to extract the energy and reference clock from the wireless access point (AP), but operates with the power amplifier (PA) to transmit packets; 2) a V_{\text{DD}} -insensitive voltage-controlled oscillator-PA that provides stable output power ( P_{\text{OUT}} ) and frequency of the BLE output data packet against the harvester’s output-voltage variation; and 3) multitag TDD and FDD broadcasting that features a frequency-retaining technique to save the power consumption when the TX tag is idle. Prototyped in 28-nm CMOS, our TX tag occupies an active area of 1.4 mm ^{2} , including a fully-on-chip micropower manager. The measured VCO frequency pushing and P_{\text{OUT}} variation are 1.74 MHz/V and < 0.05 dB against supply voltage from 0.26–0.46 V. The data-package frequency drift is 11 kHz (4.43 ppm). The system-level verification is validated with the over-the-air measurement.
Published in: IEEE Transactions on Microwave Theory and Techniques ( Early Access )