FreeLists / si-list / [SI-LIST] Common Mode and Differential Termination

[sunil-chandra.kasanyal@xxxxxx]

Dear all,

To terminate common mode and differential signals in differential traces,
following termination scheme is used:

               ---------------              Rs       A
      --------|               |---------- /\/\/\/----o GND          
               ---------------        \Rdiff/2
                                      /
Driver                                |             
                                      /Rdiff/2
               ---------------        \     Rs
      --------|               |----------/\/\/\/----o GND         
               ---------------                      B
    
  
 Transmission line has odd mode impedance Zo and even mode impedance Ze.
Then for exact termination:
Ze = Rs
Zo = (Rdiff/2) || Rs

If I place a capacitor in series with each Rs, and second terminal of
capacitor to the ground ( this is like the ac termination for even mode
signals), above relations of Zo and Ze still holds or not?? Why??

If I choose the values of Rs and Rdiff/2 such that:
Zo = Rs
Ze = Rdiff/2
Does it well terminate the common mode and differential signals ?


Thanks and Regards,
Sunil C Kasanyal
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