A WiFi and Bluetooth Low-Energy Backscatter Combo Chip With Beam Steering Capabilities

Abstract

This article introduces a dual-mode backscatter integrated circuit that supports both WiFi and Bluetooth low-energy (BLE) transmissions. It enables a multiantenna WiFi mode with reconfigurable beam steering of single-sideband (SSB) quadrature phase shift-keying (QPSK) signals, while also facilitating omnidirectional SSB BLE-to-BLE backscatter communication. To achieve beam steering, two techniques are proposed: 1) a transmission-line-less fully reflective SP4T backscatter switch is employed to minimize power loss and maximize the communication range and 2) a multiantenna array is constructed using the aforementioned SP4T switches together with a baseband phase-shifting technique to reradiate the incident WiFi signal with a controllable angle of direction. The chip implementation is based on a 65-nm CMOS process and operates at a power consumption of $5.5 \mu \text{W}$ in standby mode. In backscattering mode, it consumes $39 \mu \text{W}$ for the single-antenna approach and $88 \mu \text{W}$ for the multiantenna approach. The proposed design achieves a worst-case access point (AP)-to-AP range of 35 and 56 m for the single-antenna and multiantenna approaches, respectively.

Keywords

• Backscatter communication
• Bluetooth low energy (BLE)
• Internet of Things (IoT)
• low-power wireless system
• range improvement
• wake-up radios