Internet of Things (IoT) devices was projected to be installed in every object surrounding us. Most of the IoT sensing and communication circuits only operate for a very short amount of time and sleep or stand by for a much longer time. Basically, there are three choices for the fully integrated voltage regulators: inductor-based DC-DC converter, switched-capacitor (SC) DC-DC converter, and linear regulator. The chapter discusses the dynamic voltage scaling (DVS) power management scheme of the low-duty-cycle application. It introduces low-dropout (LDO) regulator topologies and the low-power techniques with one design example. The chapter addresses the SC DC-DC converters for low-power applications. The replica biasing technique is a simple and widely used technique in source follower-based LDO regulators, for supplying the digital circuits with intrinsic load-transient responses, or for realizing internal rails for the gatedrive buffers in DC-DC converters.