DC bias loss in ceramic capacitors: watch the resonant frequency move in real time!

In this video Dr Ali Shirsavar from Biricha, supported by ‪@OMICRONLabTutorials‬ , demonstrates the impact DC bias loss has on the value of capacitance in ceramic capacitors. Ali shows how the resonant frequency moves as the DC level across the capacitor is varied.

[@JeromeDemers]

I always wondered how I could reverse engineer and figure out DC bias of a random MLCC I found on a board. I have my answer, I take this random capacitor and place it in a LC filter and do the same measurement as you did. Sweet!

[@TheFlutecart]

I went to school for electronics when a 10uf ceramic was considered as rare as a tantalum unicorn. I'm learning a lot about these modern components lately and this info is really helpful, thanks! - The stuff they make now is pretty incredible but it has limitations, , as usual.

[@robegatt]

Very clear demonstration.

[@VandalIO]

Awesome stuff !

[@aradhanakumari4509]

Can't thank you enough for such nice explanation

[@ED99LAM]

thanks. did not know the effect of voltage on capacitance of ceramic cap before

[@JonathanGerardDias]

Guess I learn something vital every day. No more ceramics in my audio signal chain

[@user-ww2lc1yo9c]

OK so you have highlighted a problem, but what is the solution to this problem???

[@volodymyrzakolodyazhny7740]

Designing a power supply you have to add more capacitors in parallel, or use a larger size SMD caps (if we are about SMD).

[@p_mouse8676]

This is only not true for C0G (NP0) capacitors, which are extremely stable and often perform better than film capacitors. Speaking of film capacitors, they have a frequency vs voltage graph. Beyond a certain frequency the permissible voltage drops rapidly.

[@volodymyrzakolodyazhny7740]

Yes, we have Class IandClas II dielectric types. And Class Iis stable and Class II is not (as shown on the video).

[@Graham_Wideman]

It's good that you're highlighting this important, and perhaps surprising phenomenon. However, calling it "DC bias loss" makes no sense. How is this about "losing DC bias"? It's not. It's "capacitance reduction with increasing DC bias". And the surprise is that many capacitors are spec'd to possess a capacitance at their rated voltage of only 20% of their 0V capacitance (similar to the result you obtained). Given that many MLCCs are used as decoupling capacitors for power supply rails, and thus always operating with a significant bias, it's crucial that the circuit designer understand the C vs V curve for such a capacitor, and choose a cap with a voltage rating that's a substantial multiple of the actual voltage in the application -- or a cap with a larger capacitance, of course.

[@robegatt]

it means loss in capacitance due to dc bias

[@robegatt]

standard practice is to use at least double the voltage, more often 2.5x

[@therandomchannel9226]

Yes usually the one should choose two times more rated voltage capacitor then the injected voltage. Also Polymer tantal caps are ten times better when it comes to DC bias capacitance loss. But they are 10 times expensive too.

[@dobrowolsk]

@@therandomchannel9226 And they tend to randomly explode somehow.