Generate signal smaller than function generator limit

[sudil99]

I need to generate 0.5 mV to feed to IN-amp. But the minimum voltage my signal generator can generate is 10mV peak-to-peak.

I tried using this voltage divider to get 0.5mV at +ve input, but doesn't work. The output is like 20 times smaller.
How can I get this small voltage?

 

[jasonc2]

your ratios are incorrect; they are off by a factor of 10 and also you did 11:1 not 10:1.

output of your voltage divider is Vin * R3 / (R3 + R22) which is:

Vout = Vin * 0.0099 = 0.049mV peak for your 5mV peak input.

assuming you want 1mV p-p output from your 10mV p-p input, you want R3 / (R3 + R22) = 0.1, or rearrange to R22 = 9 * R3

use this tool to find available values: **broken link removed**

so e.g. R22 = 180k, R3 = 20k will work.

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p.s. i can't tell exactly what you mean so if you want 0.5mV p-p out then R22 = 19 * R3 and use that tool to find values for that instead.