Input capacitance for 100x oscilloscope probe

[CrabMan]

Hi,

I am trying to make a 100x oscilloscope probe, i googled this and found some schematics, basically for 100x probe the voltage divider ratio should be 100:1, my scopes(Tektronix TDS2002) input impedance is 1Mohm, but i don't know the input capacitance.

I tried to calculate the capacitance from whats written on the 10x probe (9Mohm, 16pF), but it doesn't work, all i get is some distortion, secondly what kind of wire should be used and i also read somewhere that for Coaxial cable the capacitance of wire should be taken into account, one more thing that I found was a small RC filter circuit near the connector end of one of the probes. Should I also include a filter in the circuit and if yes then what kind

Please help me out.

 

[jorgito]

oscilloscope probe

Hello CrabMan,

Please see if this can of any help.

Regards!

 

[FvM]

100x oscilloscope probe

Thanks to jorgito for providing the profound literature. It's still presenting the state-of-the-art for passive and previous generation active probes.

my scopes(Tektronix TDS2002) input impedance is 1Mohm, but i don't know the input capacitance

I don't have a recent Tek scope, 485 has been my last one, but I'm collecting manuals for reference. You may want to take a short look at the specifications chapter in TDS200x manual.

The basic question for your DIY 100:1 probe is the intended bandwidth. It decides, if you come along with a simple compensated RC divider or have to consider transmission line effects and provide respective dampening means or possibly a resistive cable, as discussed in the Tek literature.