voltage / temperature co-efficient of a capacitor

[diarmuid]

Basic enough question but can anyone explain to me why exactly a capacitor has a temp / voltage co-efficient?

Is it to do with the dielectric or the materials used for the plates? Do ceramic caps have higher co-efficients than others?

Thanks,

Diarmuid

 

[barry]

Because its capacitance changes depending on applied voltage and temperature. It depends mostly on the dielectric.

This might help:
https://www.niccomp.com/help/VoltageCoefficientofCapacitors-032012-R1.pdf

 

[jiripolivka]

There are many types of capacitors, with various dielectrics. Many have the problems you mention, mostly low-cost ceramic types. For high-quality audio applications, polyester capacitors are recommended, for RF applications, special ceramics.

The higher the dielectric permittivity, the higher temperature and voltage effects. Electrolytics offer a high capacitance in a small volume but they are mostly very sensitive to temperature, voltage and polarity.