Digital Electronics: Theory and Practice

Digital Electronics, or digital (electronic) circuits, represent signals by discrete bands of analog levels, rather than by a continuous range. All levels within a band represent the same signal state. Relatively small changes to the analog signal levels due to manufacturing tolerance, signal attenuation or parasitic noise do not leave the discrete envelope, and as a result are ignored by signal state sensing circuitry. Some information is intrinsically digital, so it is natural to process and manipulate it using purely digital techniques. Examples are numbers and words.

The drawback to digitization is that a single analog signal (e.g. a voltage which is a function of time, like a stereo signal) needs many discrete states, or bits, in order to give a satisfactory reproduction. For example, it requires a minimum of 10 bits to determine a voltage at any given time to an accuracy of 0.1%. For transmission, one now requires 10 lines instead of the one original analog line. The study of number systems is important from the viewpoint of understanding how data are represented before they can be processed by any digital system including a digital computer. It is one of the most basic topics in digital electronics. In computer engineering, a logic family may refer to one of two related concepts.

A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with compatible logic levels and power supply characteristics within a family. Many logic families were produced as individual components, each containing one or a few related basic logical functions, which could be used as “building-blocks” to create systems or as so-called “glue” to interconnect more complex integrated circuits. The book seeks to impart a thorough understanding of the basic concepts of digital electronics and its applications.