TRF1208EVM: TRF1208EVM

Thanks for sharing the device name. The ADC12QJ1600 is a buffered input ADC, so the input return loss should be pretty good. This means that after matching the output of the TRF1208 to 100 ohms differential in your pass band, the ADC should behave as expected with the TRF1208.

The TRF1208 is a low output impedance amplifier, and so some matching is needed here to give the anticipated response. On wideband matches, typically a 3 to 5 dB resistive Pi or T attenuator is used directly after the TRF1208 to bring the output impedance to 100 ohms differential, which then can be followed with two 50 ohm single ended filters, or a 100 ohm differential filter to give the appropriate response. This approach is seen in the TRF1208-ADC12DJ5200EVM, schematic seen below.

In the above, R181,R182,R184 make up one resistive attenuator on the OUTP output, and R186, R187,R189 make up the other on the OUTM output of the TRF1208. These resistive attenuators are located physically close to the output of the TRF1208. The value of these attenuators is 3 dB in this case. The higher the attenuation, the more loss, but the better match. Then there is a distance along the board using 100 ohm differential transmission lines into two 10 ohm resistors and the ADC itself.

This EVM shows a wideband approach to the matching. If some filtering is required, filters would be placed directly after the resistive attenuators and be either 2 single ended 50 ohm filters, or 100 ohm differential filter.

In narrowband approaches, resonant matching can be used, but this is more difficult to achieve. You can get less loss with this approach, but there is more difficulty in design and harder to predict response due to board parasitics playing a bigger part.

Let me know if any other questions come up,
Gideon