DP83849IF: Media converter : DP83849if(LVPECL) to Optical_transceiver(CML)

Hi,

I am using an optical transceiver that has an AC-coupled CML differential input and output.

I made the LVPECL termination for the DP83849IF as follows --> (TX+- pins: 50 Ohm to 3.3V, RX+- pins : 82 Ohm to 3.3V and 130 Ohm to GND, 0.1 µF coupling capacitors in series with all 4 lines).

With this termination the communication did not work.

I tried below setup as described in section 3.4.1(https://www.ti.com/lit/an/snla086b/snla086b.pdf) without firmware (no read & no write) to monitor the data on RXD lines for both PORTA and PORTB.

I have noticed that the PORTA - RXD0_A to RXD3_A lines are always 0. These lines show no  pulses when I connect the RJ45 to PC. This means that the PORTB transmit pins are not transmitting.

I think this is because of the termination and biasing of the LVPECL outputs.

Could you please tell me what should I connect to 100base-FX differential signals of DP83849if  to make the conversion from LVPECL to CML ?

Thank you.