mliccione89 wrote, "I'm not getting what I expect to see at the output of the TIA."
What did you expect to see?
It looks to me like you are sending very narrow (~ 2 ns wide) pulses into the TIA.? How much bandwidth is required to pass a 1 ns risetime?? The rule-of-thumb is at least 350 MHz.? How much bandwidth does the ISL70444SEH have?? Its datasheet claims that its GBP is 19 MHz typical -- which is much less than what you would need to maintain a reasonable likeness of your pulses with their 1 ns rise and fall times.? Perhaps it is acceptable to live with the lost rise and fall times, but I think the pulse widths are just too narrow to expect them to be faithfully reproduced by such a "slow" op-amp.
There are faster op-amps.? But it gets challenging to work with extremely fast op-amps.
Consider starting slow in your simulation (much wider pulsewidths at I1 and I2), and then watch at what point the output waveform can't keep up.
Andy
