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Why is always prefered the value of 0.1u as decoupling capacitors that they placed very close to the chips? Why don't use larger, like 0.22u, 0.47u, 0.68u or 1u for example?

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    \$\begingroup\$ It used to be 0.1uF ceramics were the biggest and cheapest devices available and were a nice physical size that matched the dip package. Today you can get and use larger values. \$\endgroup\$ – Trevor_G Sep 28 '17 at 18:23
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    \$\begingroup\$ related \$\endgroup\$ – The Photon Sep 28 '17 at 18:28
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    \$\begingroup\$ also related \$\endgroup\$ – The Photon Sep 28 '17 at 18:29
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    \$\begingroup\$ Modern tiny high capacitance caps lose a lot of capacity at typical DC bias values anyway. In fact the voltage rating has more to do with the capacitance loss than breakdown in many cases (you can think of it as analogous to saturation in inductors at higher currents). \$\endgroup\$ – Spehro Pefhany Sep 28 '17 at 19:18
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    \$\begingroup\$ Larger capacitors are not, in general, good for decoupling because they have low self-resonant frequencies. \$\endgroup\$ – dirac16 Sep 28 '17 at 19:27
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0.1uF capacitors may attenuate higher frequencies better than, say, a 1uF capacitor due to larger (SMD) capacitors having more inductance.

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  • \$\begingroup\$ That was true in the 90's, but not today. 1µF is readily available in 0402 package. You can even get as high as 22µF in 0402 package(!) \$\endgroup\$ – Timmy Brolin Apr 14 at 0:03

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