Hello There,
I have a customer who is thinking about using the TMDS181 as a transmitter and a receiver in an end to end HDMI2.0-based system. On one end, they want for the output of the TMDS181 to be AC-coupled to their FPGA so there are a couple questions surrounding that.
For TMDS181 as receiver:
The FPGA inputs have internal 100 ohm differential termination, but they can not handle the 3.3V level of TMDS. If we AC-couple the TMDS181 into the FPGA, then the TMDS181 outputs will not have a DC termination. Do we have to add external 50 ohm pull-up terminations to the TMDS181? (If we do, then will we have double termination?) Can we use a higher value pullup, say, 100 ohms each leg, knowing that for AC we'll be terminated within the destination IC? These traces run at 6GHz, so we'd really rather not add any components that we don't have to.
For TMDS181 as transmitter:
As a transmitter, it's sort of the same question on the other end. The FPGA can not produce the 3.3V DC level required by the TMDS181. So we must AC couple in to the TMDS181. Will the TMDS181 be happy in this case?
Any insight or feedback you may have for this type of application would be very appreciated. If there's any information you need that I'm missing, let me know. Thanks so much for your time!
-Amanda
