Routing of multiple impedance controlled tracks
The said chip is an adaptive filter chip which accepts either
  differential pair or 50Ω signal.


Get rid of the unnecessary impedance matching pad to convert 75 to 50 ohm: -



The front page of the data sheet says this: -


  Equalizes up to 120 Meters of Belden 1694A


And Belden 1694A cable is already 75 ohm.


  Belden 1694A is an excellent, low loss 75 ohm coaxial cable, with
  superb bandwidth, low capacitance and double shielding (one foil
  screen, one tinned copper braid).


Taken from here.

This is my only tip in the absense of your schematic.