Achieving Optimum ADC Performance In Embedded Systems Design

By Gary Hendrickson

January 8, 2007

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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 long over. This article gives an overview of ADCs and recommendations on how to apply them successfully.

ADCs (Figure 1) are found in so many applications that they are almost a commodity. Historically, converters were components requiring specialized knowledge to design and manufacture, resulting in expensive solutions, such as a 12bit/500kHz ADC sold for about $270 in 1975.

Figure 1: ADCs are used in communication, instrumentation and measurement, and computer systems, where they can facilitate DSP, information storage or both.

Modern converters have come down in price over the years, capitalizing on the same technology advances as digital ICs. That same 12bit/500kHz function is available today for less than $1. ADCs are commonly used in communication, instrumentation and measurement, and computer systems, where they can facilitate DSP, information storage or both.

The ADC function is often integrated along with digital circuitry on the same chip, but there are also applications where performance requirements dictate that a standalone ADC must be used. The cellphone is an example where the ADC function has been integrated into the digital chip, while the cellular base station (with its higher requirements) relies on separate standalone ADCs, which can deliver the ultimate in performance.

ADCs contain the following:

• Analog input(s) -- Single and multiple channels are available.
• Reference input -- This voltage can be supplied externally or may be inside the ADC.
  
  

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