[sdiy] X7R Ceramics for coupling AC audio

[Antti Huovilainen]

On Thu, 18 Sep 2008, Neil Johnson wrote:

> As for the DC effect, for small signal circuits the change in 
> capacitance will be small.  For X7R the capacitance change with voltage 
> is a few %, but for Y5V its huge, up to 80% over the operating range. 
> So running a reasonable-amplitude AC signal through a Y5V ceramic cap 
> certainly would distort it.  For a 10V-rated cap a 1-volt swing is 
> enough to affect the capacitance quite alot.

Am I wrong in assuming that "DC" in the graphs essentially the instant
voltage over said capacitor? For high enough frequencies, the impedance of 
capacitor is very small and hence the voltage over capacitor should remain 
more or less constant.

Antti

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