The future of the Internet or the Internet of Things (IoT) is an interconnection of uniquely identifiable embedded devices often referred as IoT smart devices and sensors. A large number of sensor nodes each capable of sensing and wireless communication installed in an area of interest makes a wireless sensor network. Billions of smart sensors push data to the IoT through diverse applications, including home security systems; lighting and HVAC control; utility monitoring; industrial control and automation; bridge, railway, traffic light monitoring; and various other infrastructure and environmental uses. Despite the wide difference in applications, these sensor nodes share architecture similar to wireless IoT smart devices, such as those used in the medical, health, and fitness domains.
One of the most common challenges in all sensor node design is power management. Wireless sensor nodes are often placed in hard-to-reach locations where sourcing from mains power is either inconvenient or impossible. Designers need to closely examine the power consumption associated with different operational states of the microcontroller (MCU) and the transceiver of the wireless sensor node. In a typical sensor node application, a node might sit idle for long periods of time between peak periods of activity for sensor data acquisition and wireless transmission. In other words, the power profile consists of active peaks, that are represented by tens of milliamps at maximum transmit or receive power, and long idle periods, that are characterized by quiescent current as low as tens of nanoamps.