Selecting a decoupling capacitor

This is a summary of the issues to consider when looking for a decoupling capacitor to suit your application.

1. Choose your initial decoupling capacitor parameters to fit your application.
   Consider the following:

   • Preferred capacitor physical size – 0402, 0603
   • Ceramic material – X5R, X7R, or similar
   • Tolerance – Preferably ±10 %
   • Voltage rating appropriate to the supply
2. Study the intended capacitor datasheets, ask vendors, or download a tool to extract capacitor characteristics, paying attention to capacitance stability.
   1. Ensure sufficient rejection to DC bias.
   2. Attain effective capacitance at a low AC voltage value.
      • <50 mV AC rms
   3. Check temperature curve together with AC and DC bias in the application temperature range.
3. Extract minimum and maximum effective capacitance.
4. Iterate to find the capacitor that best suits your application.