Basic Guidelines For Using Analog-To-Digital Converters
by Gary Hendrickson, Intersil Corporation

Analog-to-digital converters (ADCs, also sometimes called data converters or simply converters) change real-world analog signals such as sound, temperature, pressure and light to digital signals that can be processed in the digital domain. Analog design engineers like to say "The world is analog," but most signal processing is done by digital computers today -- the days of analog computers are over.

ADCs are found in such a large number of applications that they are almost a commodity. Historically, converters were components requiring specialized knowledge to design and manufacture, resulting in expensive solutions. A 12-bit/500-kHz ADC sold for about $270 in 1975. Modern converters have come down in price dramatically over the years, capitalizing on the same technology advances as digital integrated circuits (ICs). That same 12-bit/500-kHz function is available today for less than a dollar. ADCs are commonly used in communications, instrumentation & measurement, and computer systems where they can facilitate digital signal processing and/or storage of information. Often the ADC function is integrated along with digital circuitry on the same chip, but there are also applications where performance requirements dictate that a stand-alone ADC must be used. In cell phones the ADC function has been integrated into the digital chip, while the cellular basestation (with its higher requirements) relies on separate stand-alone ADCs which can deliver the ultimate in performance.

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