The world we live in is an analog one. Natural phenomena like temperature, speed, and light intensity used to be measured by analog equipment. Analog quantities take a continuum of values between a minimum and a maximum. With the advent of digital technology, the decline of processor prices, and increasing processing power, discrete-time processing became a viable alternative to continuous-time processing. Except for the switched capacitor devices, most discrete-time applications use binary arithmetic. A binary digit takes on one of two values: a 0 or a 1. Computers, microprocessors, and digital signal processors (DSPs) do their arithmetic operations using binary numbers. This forces us to convert analog quantities to digital. Because the other number systems cannot be efficiently handled with digital hardware, we use the binary system. The analog-to-digital conversion is performed by electronic devices called analog-to-digital converters (ADCs.) Once the signal is digitally processed, the result may be sent back to the analog world using digital-to-analog converters (DACs.)