Introduction to Power Management

The advancements in CMOS technology have enabled the evolution of low power circuits and systems in many applications including wearable biomedical devices. It allows the devices to operate at sub-microwatt power range and opens up a new era of the Internet of things. These new devices require small size with near perpetual lifetime. However, the traditional battery technology is not scaling at the same rapid rate as the shrinking of transistor size. Therefore, there is a need for efficient management of the power source to reduce both dynamic and leakage power of the device and a need to increase the energy sources via energy harvesting. The introduction of energy harvesting brings some design challenges since the harvested energy has variable voltage and it depends on the availability and size of the harvester. Therefore, a power management unit is needed to manage the energy transfer from the harvester and control the power distribution and consumption of different blocks in the device.