Measure bandgap output voltage

[mohmohcha]

Help! Measure nA bandgap reference output voltage.

Hi all.

I am trying to characterize a nA bandgap reference, I am now using Agilent 34410 multimeter. Set the input R to 10 Gohm because of the large output R. The reading varies a lot. Added 100nF decoupling cap to the output, a bit better but still not stable (in the order of 100uV).

Could anyone tell me what the problem is? Is it a correct way to do it? Is it because of 1/f noise?

Sharing experience, Suggesting testbench or reading will be appreciated.

Thanks.

 

[erikl]

The output impedance of your nA bandgap reference will be in the order of MΩ or even below, so you could well see 1/f noise in your consideration interval of seconds. Try a much larger decoupling cap instead.

 

[johnjoe]

Or try to use some chopper amplifier.