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OPA4197: Selecting Proper ADC Buffer Amplifier

Josh Tombs
Prodigy 90 points
Part Number: OPA4197

How do I select which op amp is the best ADC buffer for my application? I filtered based on input bias current, noise, etc. but it doesn't seem that every op amp summary page includes "data-acquisition systems" or something related.

I am building a signal conditioning card that I would like to use for general purpose data-acquisition systems. Ideally this op amp will work with any DC or AC input up until about 100 KHz. Other than that I need it to go up to +/- 10V rails, single ended output. There seem to be thousands of op amps to select from, how do I chose which one is best for my application??

  • 0
    TI__Genius 13620 points

    Hi Josh,

    This is actually somewhat of a complex question, and will depend greatly on your design specifications. 

    • What ADC architecture are you considering? SAR converters and delta-sigma converters both have challenges associated with driving them which should be considered when selecting an op amp.
    • What resolution and sample rate are you running at? This will set some constraints on the amplifier bandwidth you'll need, as resolution and sample rate both dictate the required settling time and bandwidth for the op amp.
    • What level of offset/noise is acceptable to you? 
    • Any additional requirements for this design? For example, do you need high impedance inputs to allow direct connection to high impedance sensors, or will there be additional signal conditioning ahead of this stage? 

  • 0 in reply to Alex Davis
    Prodigy 90 points
    Alex,
    I am trying to build this signal conditioning card to be as universal as possible. It would be great if I could design it generically enough to fit as many architectures as possible. That said, I will answer your questions to the best of my ability.

    - SAR converters
    - Sample Rate adjustable 1kHz - 100 kHz
    - As low as possible, I do not have a noise spec
    - The output will be going directly do an ADC, inputs will be interfacing directly with sensors, so high impedance inputs would be good. I also plan to have a resistor divider to help attenuate large amplitude DC signals.

    Let me know if that helps answer my question at all. I have since found the OPA419ID which looks like it satisfies most of my criteria, but I am very curious to learn about op amp selection so please answer with general best practice tips.

    Thanks!