The process of integrated circuits (IC) started its era of very-large-scale integration (VLSI) in 1970’s when thousands of transistors were integrated into a single chip. Since then, the transistors counts and clock frequencies of state-of-art chips have grown by orders of magnitude. Nowadays we are able to integrate more than a billion transistors into a single device. However, the term “VLSI” remains being commonly used, despite of some effort to coin a new term ultralarge- scale integration (ULSI) for finer distinctions many years ago. In the past two decades, advances of VLSI technology have led to the explosion of computer and electronics world
