A 90-nm CMOS 5-Mbps Crystal-Less RF-Powered Transceiver for Wireless Sensor Network Nodes

This paper presents a 90-nm CMOS batteryless transceiver for RF-powered wireless sensor networks. The circuit is made up of a RF energy harvesting module that is implemented through a multi-stage rectifier, a power management unit, and a PLL-based RF front-end that enables TX carrier synthesis by exploiting the RF input signal as a reference frequency. This avoids the use of a local crystal oscillator, thus implementing a highly integrated low-cost wireless transceiver. An active narrowband transmission scheme is adopted with the aim of overcoming the reader self-jamming that limits the operating range of backscattering-based RF-powered devices. The circuit supports a 915-MHz FSK downlink and a 2.45-GHz OOK uplink, while achieving a data rate up to 5 Mbps. It operates with an RF input power as low as -17.1 dBm.