Self-Regulating Load Voltage in a CMOS Cross-Coupled Rectifier

This paper presents a novel method for achieving both rectification and load voltage regulation without requiring any control circuitry. We reveal that a current-driven CMOS rectifier with dual cross-coupled transistors provides a constant DC load voltage regardless of variations in input current magnitude and load. Circuit analysis using ideally modeled transistors clearly explains the mechanism of constant voltage operation. Simulation and experimental results confirm that the cross-coupled rectifier incorporated into a wireless power transfer system provides a regulated load voltage independent of input current, inter-coil distance, and load variations. The proposed method greatly contributes to simplifying systems that require both rectification and regulated DC voltage, such as wirelessly powered implantable medical devices.