Analysis and Design of a Reconfigurable Rectifier Circuit for Wireless Power Transfer

An efficient and reconfigurable rectifier circuit, with the capability of automatically switching from low-power to high-power operation mode, is presented in this paper. The new topology allows the rectifier to convert RF power to dc power efficiently over an extended input power range. The circuit consists of diodes as rectifying elements and of n-channel field effect transistor in a depletion mode acting as the automated switch. Without using an external dc source, the circuit directly uses the rectified output dc voltage to bias the transistor, allowing high conversion efficiency over a wide input power range. This results in a compact and self-contained circuit. A total of two prototypes optimized for near-field and far-field wireless power transfer systems are fabricated and the measured results show that the performance exceeds that of the conventional rectifier circuit, which can only stay efficient over a limited range of the input power. The proposed design can maintain more than 50% of conversion efficiency over more than 25-dB range of the input power, with peak efficiency of 88% and 80% for near-field and far-field rectifiers, respectively. A system-level validation also confirms the improvement of the proposed rectifier design.