I was told some oscilloscopes have 50 ohm impedance settings for radio frequency measurements for impedance matching (as opposed to one 1M ohm resistor and a 10pF capacitor in parallel for load impedance, which is good for low frequency measurements). I was able to find a circuit schematic of an oscilloscope. for the usual 1M ohm and 10pF capacitor in parallel. But i haven't been able to find a circuit diagram for the 50 ohm impedance oscilloscope. Id lile to know what the oscilloscope circuit looks like for the rf 50ohm impedance settings
There are many sources on the subject, you need to search for something like "1 GHz PC scope". Many IC manufacturers offer amplifiers that can work only with 50-Ohm sources and loads. In fact, it is very difficult to get GHz-range with 1 MOhm input.
Here is an example, a reference design from Texas Instruments, "50-Ohm Oscilloscope Front-end Design Guide" . It looks like this:
All components are commercially available, and good luck.