I have a 5 V, 50 Ω input single pulse signal (<1 ms pulse width) going into Trenz TE0711 (operating @3.3 V and 50 MHz clock). Since the input signal is too high of a voltage, I am trying to find a way to reduce the voltage and keep jitter low (<1 ns). I also want it to be dummy proof where if someone puts in a high-voltage signal or an AC signal it doesn't fry the FPGA. I am not familiar with analog electronics, so I apologize if this is a simple question.
Currently, I am thinking of having a 3 V zener diode to act as a regulator and use a current limiting resistor (250 Ω) in front. However, I am not familiar with other components that may be out there that could meet my needs. I am concerned that zener diodes may have high jitter, but I just don't know. I am also worried if the 250 Ω resistor will cause a mismatch with the 50 Ω input signal and cause reflections.
Lastly, what would be the best way to test this? Could I use a delay/pulse generator and generate a 5 V, 50 Ω single shot pulse and just connect it directly onto my circuit that is on a breadboard and hook up an oscilloscope? Or, are there other ways to ensure proper and precise measurements?