Question on current pulse measurement

[wufeng]

Hi guys,
I want to measure the current of a 0.1ms signal. The amplitude of the current is about 100nA. Does anybody know how to do it? Thanks!
Jianwei

 

[FvM]

E.g. with an OP I/V converter.

 

[audiomik]

Jianwei
Best option for you would be to use a Current Probe, for example a Tektronix P6042 or similar.

However there are a number of 'DIY' AC Current Probe designs based upon Ferrite Torroids if you have the facility to calibrate them.
Some info for how you might make one here:Simple RF Current Probes

Another alternative could be to try using a series resistance and view the voltage across it with a Differential 'Scope input to then be able to calculate your pulse current.

hope this assists
Mik

 

[ea.arun]

an opamp based transimpedance amplifier with low bias current shall be used.......adjust the feedback and derive the current from the output voltage......

 

[audiomik]

think a bit of important information I omitted to ask, is what is the (common mode) voltage to ground at the measurement point?
Mik

 

[FvM]

a bit of important information I omitted to ask

Did you forgot to ask for the details? (there are some more). I think, the original poster should tell a more clear question.