Low Power Input and Reference Driver Circuit for ADS8318 and ADS8319

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The "one size fits all" approach to operational amplifiers is not effective. Every application has its own specific requirements that must be fulfilled. Appropriate selection of the op amp that drives an analog-to-digital converter (ADC) in a low-power application is a critical step. Most available low-power op amps trade off low-power features with other parameters such as bandwidth, settling time, slew rate, or amplifier noise, and typically, these trade-off areas play a crucial role in data conversion applications. This report specifically addresses the matching of the THS4281 (a very low power, high-speed op amp) with the ADS8318 and the ADS8319, two 16-bit, 500-kSPS, low-power, serial, successive approximation register (SAR) ADCs. Circuit performance is demonstrated through test results and several recommendations are presented regarding op amp selection for both the ADS8318 and ADS8319.