I. Introduction
As transistor density of processors and memory devices, as well as the memory capacity and bandwidth, continue to grow, the power consumption of computing systems has also been increasing exponentially, resulting in tremendous heat generation, even to the point that threatens to disrupt the operation of the system under normal conditions [1]. An increasing chip temperature due to an excessive power dissipation has a significant impact on other design metrics, such as reliability, cost and especially on performance. Cooling down the chip temperature using mechanical methods such as cooling fans, heat spreaders, and heat sinks becomes inadequate and too expensive. This is particularly true for multi-layer chips (2.5D and 3D chips) [2], [3] designed for future generations of IoT applications [4]. Thus, dynamic thermal management (DTM), i.e. to adjust a chip's temperature by dynamically adjusting its performance, has become an appealing solution.