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Choosing a capacitor for an op amp integrator

  1. Dec 4, 2008 #1

    Mapes

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    Hi folks,

    I've been looking into op amp integrators as a way to add ramps to signals. I'd like to get a ramp rate on the order of 0.1 V/s, which suggests the use of capacitors in the neighborhood of 10-100 uF. Many electrolytic and tantalum caps have these values, but a polarized cap isn't appropriate with the bipolar charging sequences used in integrators.

    I've heard that polarized caps are sometimes attached back-to-back to simulate a nonpolarized cap, but that the response is non-linear. Nonpolarized caps with the desired values seem relatively expensive (an exception appears to be TDK's multilayer ceramic caps, e.g. FK24Y5V1A106Z, sold by Mouser, if these are non-polarized). Any suggestions or experiences in this area?

    Thanks!
     
  2. jcsd
  3. Dec 4, 2008 #2
    I would think you could find a way to keep the capacitance below 1 uF. Also, non-polarized electrolytics are available. However, I don't think an electrolytic is the best choice since it will have significant leakage.
     
  4. Dec 4, 2008 #3

    dlgoff

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    You could alway parallel several non polar, non electrolytic caps.
     
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