[SI-LIST] Re: Bandwidth & AC coupling capacitor

It is all about the series impedance and impedance continuity.  Your PCB 
etch is nominally a 50 Ohm signal transmission line.  From about an 
octave above the mounted SRF, the capacitor looks like an inductor with 
some loss.  If the interconnect in the region of the capacitor is 
arranged such that the parasitic shunt capacitance Cshunt = Lcap_mounted 
/ 2500, then for wavelengths that are long compared to the length of the 
region surrounding the capacitor, the L/C approximates the impedance of 
the rest of the transmission line and there is little impedance 
discontinuity.

Steve.


icer world wrote:
>       When use AC coupling for interconnection,the capacitor is about 
> 0.1-0.01uF.However,the resonance frequency of this kind capacitor is below 
> 100MHz,Would signals above 1GHz such as PCIe signals can pass it without no 
> bandwidth reduced?Can anyone give me a explanation? Thanks!
>
>
>       
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