(Dec 7) Low-power analog circuit techniques for small internet of things (IoT) systems

Although the improvement in circuit speed has been limited in recent years, there has been increased focus on the internet of things (IoT) as technology scaling has decreased circuit size, power usage and cost. This trend has led to the development of many small sensor systems with affordable costs and diverse functions, offering people convenient connection with and control over their surroundings. This talk discusses the major challenges in realizing small IoT systems and their solutions, focusing on non-digital blocks, such as power converters and analog sensing blocks, which have difficulties in following the scaling trends of digital circuits.

   Due to the limited energy storage and harvesting capacity of small IoT systems, we need energy harvesters and voltage regulators with low quiescent power and good efficiency in ultra-low power ranges. The small system size and low power level render switched-capacitor-based power converters power converter favorable because of their easy integration on chip and control for low power output. This talk discusses several switched-capacitor converter techniques such as power-efficient converter topology design, converter realization and control.

   To further improve the power efficiency of IoT systems, analog circuit blocks essential to most wireless IoT systems are also discussed. A capacitance-to-digital sensor interface and a clocked comparator design are improved by their digital-like implementation and operation in phase and frequency domain. Thanks to the removal of large passive elements and complex analog blocks, both designs achieve excellent area reduction while maintaining state-of-art energy efficiencies