Harmonic-Based Integrated Rectifier–Transmitter for Uncompromised Harvesting and Low-Power Uplink

Wireless uplink of a sensor node based on modulating rectifier-generated harmonics is promising for lowered energy consumption and Tx-to-Rx leakage. The existing solutions need to balance between maintaining the rectification performance and modulating the reradiated harmonic. In this article, a novel controllable second-harmonic termination (CSHT) is proposed to modulate the reradiated second harmonic in amplitude without compromising the wireless power reception. By combining a CSHT and a rectifier, an integrated rectifier–transmitter (IRT) is formed. An analytical model is derived for designing CSHTs, while the relationship between the CSHT, the diode impedance, and the reradiated harmonic power is revealed for the IRT. As a proof of concept, an IRT prototype at 2.4GHz was designed and experimented. An uplink data rate of 2 Mb/s was achieved when the IRT was fed by a transmitter with +25-dBm output power at a distance of 4 m. The data transmission of the proposed IRT consumes power less than 12.2 pJ/bit while maintaining the wireless power rectification performance.