An Inverter-Based Bidirectional and Reconfigurable RF Energy Harvesting Circuit with Rectifier and Oscillator Modes
A bidirectional circuit that can be reconfigured as a receiver for rectifying RF power for energy harvesting and as a power oscillator for transmission is described. Except for one switch, power flow is completely reversible. The circuit block is compact and suitable for integration in time-division multiplexed wireless sensors. The circuit design is based on the concepts of time-reversal duality where the oscillator and synchronous rectifier are circuit duals. An experimental circuit is implemented in 65 nm CMOS technology using an inverter-based circuit topology and operates at a frequency of 5.8 GHz. The measured peak efficiency is greater than 40% in both operating modes. A self-bias mechanism is employed in the circuit to satisfy both modes of operation.