There is some information about single-ended input impedance, shown in the table 1. It seems the data were measured on the demo board. Can you provide deembedded S-parameters of the LTC5582 up to 10 GHz?
here's single ended impedance s1p data up to 10GHz.
the s11 file measured on the eval board with reference plane at the end of the transmission line.
we don't have s-parameter that de-embed the pcb.
use a shunt 68ohm resistor at the input for simulation…