Low Power Current Sensing Circuit for DC–DC Converter in Energy Harvesting Circuits

摘要

A low power current sensing circuit for a current mode control DC–DC buck converter is implemented in TSMC 0.18 μ m 3 V Technology. In order to achieve low power, all blocks must be turned off when not sensing the inductor current; this is during discharging mode. Thedesign implements a dedicated current reference which is switched on and off. It takes advantage of the nature of the clocks being non-overlapping. Even though the current reference which sets the bias points for the voltage mirror is turned off when the whole circuit is not sensing the inductorcurrent, there is enough time for the bias points to reach its values when the charging mode is just about to start. The current sensor senses the inductor current during charging mode, and maintains an accuracy of 97.34% with respect to the reference circuit and power consumption of 128 μ Wamounting to 10.48% power savings for a target peak inductor current of 113 mA.