Application Acceleration With FPGAs
Programmable Acceleration Cards (PACs), DCP, FPGA AI Suite, Software Stack, and Reference Designs
493 Discussions

How to calculate Capacitor value for AC Coupling.

mhm00
Beginner
1,062 Views

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,for AC Coupling we need capacitor,so when I start to find the value of the capacitor I understand that I need to know the INPUT IMPEDANCE at the dedicated REFCLK PINS of the FPGA, but I didn't found the information about INPUT IMPEDANCE at the at the dedicated REFCLK PINS.

so what would be the INPUT IMPEDANCE at the dedicated REFCLK PINS of theCYCLONE V FPGA?

0 Kudos
3 Replies
Nathan_R_Intel
Employee
839 Views

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

0 Kudos
mhm00
Beginner
839 Views
0 Kudos
Nathan_R_Intel
Employee
839 Views

Sure.

0 Kudos
Reply