A low noise, high power efficiency supply regulator for near-field power delivery

摘要

In order to deliver near-field electromagnetic power to a biomedical device or an RFID tag efficiently, the downlink signal is preferred to be at a high voltage level. To reduce power consumption and meet low supply requirements, it is advantageous for the remote device power supply to step-down the input voltage following rectification, typically using switch-mode regulators. The output ripple of a switched capacitor converter is inversely proportional to the filtering capacitance at the output node and switching frequency. In this paper, a hybrid DC–DC converter utilizing a switched capacitor regulator in master–slave configuration with a linear regulator is presented. Linear regulator actively cancels the switching ripple, while low frequency and DC current is provided by the switched capacitor converter. The converter is designed to receive an average input voltage of 5 Vpk from the receiver coil, with an output voltage of 2 V, and 5 mA of output current. The proposed regulator is fabricated in 0.35 μm technology. The power efficiency is measured to be 67%, with a nominal peak to peak ripple of less than 2 mV at the output.