I have a schematic for a current sensing circuit using a dedicated TI differential amplifier part for current sensing applications. The schematic also includes an "impedance matching" part for connecting the voltage output of the differential amplifier to a BNC coaxial cable. This coaxial cable then can be attached to the PCB and then plugged into an oscilloscope.
The impedance matching bit consists of a potential divider of resistance 5-MOhms and 75-Ohms. I don't understand how or why this would work (my understanding of impedance matching is a bit iffy I'm not going to lie). I was told this bit of the circuit was taken from the internet and I've tried googling around but couldn't find the original source. Could anyone help explain how this potential divider impedance matches to a 50 Ohm BNC coax?
I tried simulating it in LTSpice to maybe get some insight into how it would work but I don't think my model of a coaxial cable was correct. I found some typical values of inductance and capacitance from here and then measured the resistance of the cable and included that too. I also looked up the input impedance of the oscilloscope which said it was 1-MOhm and an input capacitance of 13pF. I don't think I'm simulating it correctly however, is this circuit model a good enough approximation? From the article they linked it says there's also a parallel conductance, but I have no way of measuring this so have omitted it.