Successive-approximation (SAR) ADCs offer high resolution, excellent accuracy, and low power consumption. Once a particular precision SAR ADC has been chosen, system designers must determine the support circuitry needed to obtain the best results. My article focuses on the circuit requirements and tradeoffs in designing the ADC driver front end.
The front end consists of two parts, the driving amplifier and the RC filter. Choosing the right amplifier and RC filter for a SAR ADC can be a challenge, especially when the application needs differ from the routine datasheet usage of the ADC. Looking at the various application factors that influence amplifier and RC choice, I provide design guidelines that lead to the best solution.