Generating microvolt input signals for IC testing

[blurryeyes81]

microvolt signal generator

Hi, I'm currently testing an EEG biomedical amplifier IC. Can anybody recommend me a way for generating input signals of around 50 microvolt peak-to-peak. The arbitrary waveform generator in my lab can only provide signals of 1 milivolt p-p and above.

And is there any way to verify the small microvolt input signal using a standard oscilloscope?

Thanks!

 

[IanP]

oscilloscope microvolt

I would build a shielded container and put a 1:200 ( or more) resistive voltage divider, so the input signal will be of at least 10mV level. By doing this, you will reduce the noise in the same ratio.
I don't think you can use a standard oscilloscope for this extremely fragile excercise ..
Regards,
IanP

 

[uncle_urfi]

microvolt generator

There is always a 'lab-mouse' or some other poor animal. connect probes to their heads. Realistic EEG testing!

Getting (to) a biomedical 'lab' would help. What we do is that if we don't have the required equipment, we go to some other lab that has that equipment, although this is not my field so i am not sure how it works in the biomedical engineering industry.


Alternatively, I am just thinking; Why not use an RF generator like the Rhode&Schwartz type with a -40 dBm output level. All sorts of modulations and output frequencies are possible.
Or using a higher output level followed by a high quality RF attenuator to get the desired level. I don't know if you have low frequency attenuators available, check minicircuits.com. Your target frequencies should be very low.

If your impedance level is 600 ohms (instead of the RF standard of 50 or 75 ohms) then you need to do some serious input matching; that would be an issue.
(Or did you chip take this impedance level into account?)

May be you can see the output on a spectrum analyzer (matching again!); until you get a better scope.

 

[blurryeyes81]

milivolt signal from function generator

Thanks for the quick replies guys.