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Maybe this was asked before, but I have a capacitor set with electrolytics and ceramics. And all the capacitors which has capacitance equal or bigger than 1uF are polarized electrolytic capacitors.

Imagine I have a +/-5V sine wave input swing(coming e.g. from a strain gauge amplifier); and if I were to use an electrolytic polarized capacitor as below:

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It seems that the capacitor voltage at its positive lead goes below ground when the input becomes negative swing. Does that mean electrolytic capacitor should never be used for such filter application? And will it not work at all if used?

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  • \$\begingroup\$ It should not be used in this application, no. Use a non-polarized capacitor if the signal can go negative, or give it a more negative voltage on its negative lead than the signal will ever go. \$\endgroup\$
    – Hearth
    May 28 '19 at 23:58
  • \$\begingroup\$ E-Caps might tolerate 5% of rated voltage in reverse direction. Non-polar E-caps exist. \$\endgroup\$ May 29 '19 at 0:00
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Tantalum electrolytic capacitors can live with some small reverse current, but aluminum electrolytics will not do as well. I would not use a polarized capacitor in this way for any circuit in production. Your options are high dielectric ceramic capacitors (but they have poor change in capacitance with voltage) , and non-polarized electrolytics, which are basically two electrolytic capacitors back-to-back. Both of these solutions exhibit a high value of dielectric absorption. If possible, make all your impedances larger, so you can use smaller value capacitors. Taking this an extreme will force you to use some active components (that is, op amps) in your signal conditioning.

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