2.1 Basics of Modern Digital Circuits
Since the invention of complementary metal-oxide-semiconductor (CMOS) technology, digital logic circuits have contributed to processing massive digital data. Examples of the applications based on the digital processing are laptop computers, smart phones, wearable devices, smart cards, and so on. In this chapter, we learn the basics of how to implement a digital hardware. Especially, synchronous design, which is commonly applied to most of the digital circuits, is introduced as a key technology.
The synchronous design uses a clock signal that is distributed to the whole synchronous circuits, and takes the timing of operations. To look into the details of the synchronization mechanism, the building blocks in the synchronous circuit are described. As they play an important role in the digital circuits, memory modules are also discussed.
2.1.1 Digital Circuit Design Method
Many modern digital circuits are implemented based on the synchronous design method that can handle integrated circuits (ICs) by using commercial design automation (DA) tools. As illustrated in Figure 2.1, the synchronous design starts from register transfer level (RTL) coding after defining a design specification. At this design stage, the designers can know the speed performance and the design validity by RTL simulators. Different from a normal program code of C language, an RTL code has information of timing that determines when ...