generating voltage source of 100microvolts to 1mV

[saur]

Hello,

I want to design a voltage source of with voltage ranges from 100 microVolts to 1 mV. I want it for biomedical instrumentation(EEG/ECG). I was thinking of voltage divider but that would not work because of resistance and supply noises. Please suggest me some better way.

 

[(*steve*)]

What current is required?

What noise level is acceptable?

 

[saur]

current- order of milliamps.
This voltage is a kind of simulation since we can not use rats or humans frequently in labs.
This signal will be amplified and processed.
noise levels- around 50 microvolts

 

[Militoy]

50uV is an enormous amount of noise to be riding on a 100uV to 1mV voltage level - thats 5-50% noise. You might want to revisit your requirements - and make sure what noise level is acceptable. If 50uV is the actual requirement - you can probably get away with a resistive divider - even if it's made up of 2 cent carbon comp parts. BTW - I'm guessing that you are looking for a DC voltage source - you haven't mentioned whether it's AC or DC you're looking for. At least it's not patient - contact equipment.

 

[saur]

@Militoy
Yes, you are right. 50uV is an enormous amount of noise to be riding on a 100uV.
But the waveforms observed at various membranes of stomach are of that form. Intention is to extract the peaks which have the actual signal. Rest all is noise. Please refer to the image attached. My signal is almost like 'c'- ictal. The spikes might be slightly longer as far as i remember from the diagram at lab.
Also, the signal is observed to have a very small variation like 0.05Hz. that is, the spike happens to appear after 10 to 20 seconds.


@steve
current requirement is just that , it should be enough to be applied to input of opamp. (i.e.) voltage divider should not get loaded after connecting opamp.

Thank both of you for giving your valuable time for reply!

 

[(*steve*)]

OK, do you want a noise source, or a voltage source?

It sounds like the required current is not 1mA, but something far less.

What do you want this for again? The more you explain the less I'm understanding.

 

[saur]

The thing is that , the waveforms are the outputs of the sensors applied on body parts- eg.stomach. Now, we can not use human beings (also, test rats are difficult to get), so, i am trying to produce the signals by doing some circuit which will emulate the output given by sensors. So, its a voltage source not noise.

 

[(*steve*)]

Do you want this voltage source to be your input signal (e.g. 100uV with 50uV signal superimposed on it)?

Or do you want pure DC that you will use (somehow)?

You're still not being clear.

The former is a signal source, the latter is a voltage source. Noise on a voltage source is something you don't want, it's not your signal.