I'm a bit confused how this type of circuit should be terminated. I have no experience with transmission lines, so I do not know where to put 50ohm resistor.
It's basically output from opamp, there will be BNC connector and I want to connect it to an oscilloscope.
Bandwidth would be 100MHz.
Is it necessary to put 50ohm resistance like this?
Or the 50ohm resistor should be like this?
Or there should even some termination at the "other end", between end of coaxial cable and input to oscilloscope?
Or just put 50ohm termination on the "other side"?
My feeling is that option c) is correct, but I'm really not sure.
I have simulated those circuits in LTspice (it is able to simulate transmission lines).
It looks like this:
I have captured voltages at the ends of that transmission line and current going down to transmission line (actually current through R7). Voltage source sends 10V pulse.
The pulse has 10V peak at the end (output from transmission line). But bounces back to the input of transmission line. There are 2 current peaks +100mA and -100mA.
It looks like the output of transmission line sees many bounces (with 20V peaks). And the current peak is 200mA.
Output sees 5V pulse. Current peaks at 100mA. No bounces.
Output sees 10V pulse. Current peaks at 200mA. No bounces.
So it looks like a) is the best option (output sees 10V, and there is only 100mA current peak), but I don't know whether that bounced pulse back to the input of transmission line could cause some problems or not.