0.5 V output digital low dropout (DLDO) voltage regulator with VCO-based digital feedback loop

The emergence of wireless sensor networks and its increase in applications call for increasing the number of sensors to extend its functionality. These networks sense and send data periodically hence the need for power management. Two techniques are usually used to extend a node's life namely low power operation and energy harvesting. The power management block would maximize both techniques. A digital low dropout regulator is chosen for its ability to operate in low voltage supplies as well as its ability to regulate and produce an output that is stable with minimal ripple. A VCO was used as a A/D Converter to improve transition response time by allowing multiple PMOS switches to be turned on/off. The proposed regulator was able to supply the necessary voltage of 500mV from an input supply of 1V with a 0.275% regulation error. It achieved 84.78% current efficiency and a settling time of 160.7 us. The digital low dropout regulator with VCO-based digital feedback loop is capable of delivering challenging requirements to a wireless sensor node and enables integration with dynamic voltage and frequency scaling to further improve the lifetime of a single wireless sensor node.