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Design >> Analog Design >> feedback noise for capacitive divider
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Message started by Marianne on Oct 15^th, 2013, 10:27am

Title: feedback noise for capacitive divider
Post by Marianne on Oct 15^th, 2013, 10:27am

Hi,
my question is about the input-referred noise of an opamp when I use a capacitive feedback (see picture).
In different papers and books I find that there is the following relation between the noise of the opamp with and without feedback:
Vnoise^2 = (Cgg(Input Transistors)+C1+Cfeedback/C1)^2*V_ota^2
That seems to be a capacitive divider somehow but I cannot derive that equation for myself...
Hope someone can help me