Analog circuit signals can range from zero to high supply voltage. Analog circuits work on the basis of shifting wave creation.

In a radio, for example, an analogue circuit converts sound waves into analogue electric waves. These signals can be stored and amplified using an Analog Amplifier before being converted to sound waves by the speaker.

Analog circuits deal with signals that can fluctuate in voltage from zero to full power supply voltage. This is in contrast to digital circuits, which almost exclusively use "all or nothing" signals, which are voltages limited to zero and full supply voltage, with no legitimate state in between.

To underline the genuine continuity of signal range disallowed in digital circuits, analogue circuits are frequently referred to as linear circuits, but this designation is sadly inaccurate.

Just because a voltage or current signal can smoothly vary between zero and full power supply limitations does not entail that all mathematical relationships between these signals are linear in the "straight-line" or "proportional" sense. Many so-called "linear" circuits, as you'll learn in this chapter, have nonlinear behaviour due to physics or design. 

IC (integrated circuit) components are used in the circuits in this chapter. These components are actually interconnected networks of components made on a single wafer of semiconducting material. Students, hobbyists, and professional circuit designers all benefit from integrated circuits that provide a variety of pre-engineered functionality at a low cost.

Most integrated circuits provide the same functionality as "discrete" semiconductor circuits at a lower cost and with improved levels of dependability. When power dissipation levels are too high for integrated circuits to manage, discrete-component circuit architecture is usually preferred.