Forum Discussion

mhm00's avatar
mhm00
Icon for New Contributor rankNew Contributor
6 years ago

How to calculate Capacitor value for AC Coupling.

I'm using Cyclone V 5CGXFC5C6F23I7N FPGA. In Transceiver section,the clock for the REFCLK is provided by External OSCILLATOR and its frequency is 125MHz, LVDS IO Standard,and I'm using AC COUPLING...
Nathan_R_Intel's avatar
Nathan_R_Intel
Icon for Contributor rankContributor
6 years ago

Hie,

Apologies for the delayed first response. The typical response time is within 24 hours, but this case was assigned to me and it was a delay from my part to provide response in time.

The Input Impedance of the dedicated REFCLK pins of the FPGA is 100ohms. This is available in the datasheet

Refer to Table 21, listed as ON-chip termination resistors)

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/cyclone-v/cv_51002.pdf

I hope this answers your question. Do let me know, if you have further question, I will provide an update as soon as possible.

Regards,

Nathan

  • mhm00's avatar
    mhm00
    Icon for New Contributor rankNew Contributor
    6 years ago

    Thank you for the support.