DS90UB953-Q1: Common Choke make transmitting quality bad, how to balance both transmitting quality and EMI quality?

Hello David,

where exactly are you using the CMC?

Are you using STP or Coax ?

Are you using PoC ?

1： STP 

2：separated power line，no POC

This is not expected behaviour!! Normally you will see small difference between with and without CMC !!

Which CMC are you using?

CMC is ACM2012-900 ，from TDK

This CMC is not suitable for FPD-Link. It is good only for applications with max Frequency of 1000MHz.

If you are using the pair UB953-UB954 then your link frequency range is 20MHz - 2.1GHz. So you will need a CMC which has low Insertion-Loss for this complete range.

Dear Sir，

please see TDK  ACM2012H-T05 type, it is said it can be used for hdmi，dvi，usb3.0 pice and balabala. it also show differential resistance at 100Mhz. is it ok for UB953 and UB954?

If  not, can you share me a  detailed and  suitable common choke?

Thanks.