It is easy to forget that digital systems are really large collections of analog electrical circuits being operated in a digital manner. It is easy to forget this until the digital components need to be connected to adequate power supplies, until digital circuits experience noise problems, and until digital systems need to exchange stimulus and control with our analog world. An understanding of basic circuit theory and a working knowledge of fundamental analog principles provide a digital engineer with confidence and the ability to design a system that will work reliably at the end of the day.

This chapter begins to peel back the veil of analog circuit theory by starting with the basics of Ohm s law, units of measure, and basic circuit analysis techniques. After presenting DC circuits composed of resistors and capacitors, the discussion moves on to frequency-domain analysis and AC circuits. These topics are presented with a minimum of mathematical complexity, because the goal is to support a digital system rather than focusing on analog signal processing. Filters are introduced in the second half of the chapter. Relatively simple filters are common in digital systems, partly because of the need to reduce noise so that more sensitive components such as oscillators and interface ICs can operate properly.

Constructing digital systems in a reliable manner requires a foundation in analog circuit behavior, and the remainder of this book...