CDCLVP1208: legacy AC-coulping cap vaule

?? ?

Prodigy 10 points

Part Number: CDCLVP1208

I see some disscution for value of the coupling capacitors in page 7 of TI technical application report SCAA056.

If possible to replace legacy AC-coulping from 10nf to 4.7nf FOR LVPECL output to CML 156.25MHz application ?

over 2 years ago

0 Julian Hagedorn over 2 years ago

TI__Mastermind 20900 points

Hello,

yes, it is possible to lower the AC coupling cap to 4.7nF.

regards,

Julian

0 ?? ? over 2 years ago

Prodigy 10 points

Is any fromula to calculate it？

0 Julian Hagedorn over 2 years ago in reply to ?? ?

TI__Mastermind 20900 points

Hello,

the AC coupling cap and the load forms a high pass filter. With this formula you can calculate/estimate the cut off frequency of that filter. A simple view is that frequencies lower than that cut off frequency will not pass.

f=1/(2πRC)

The estimated cut off frequency should be at least 1/10th of the clock frequency. But I would recommend to use at least 1/100th.

regards,

Julian

Clock & timing

Clock & timing forum

CDCLVP1208: legacy AC-coulping cap vaule