Hi all. I'm calculating the total rms noise of a circuit: what have I to do when I transfer the first stage noise voltage at the output of the second stage? Multiply it for the second stage gain (and sum with the second stage output noise through Pythagorean theorem) ? thanks in advance.
Regards.
Vincenzo,
It sounds like you are on the right track with calculation of the rms noise; in order to calculate the total output noise, the first stage output noise must be multiplied by the gain of the second stage, and since the noise of the first stage is NOT correlated with the noise of the second stage, it must be summed up with the second stage noise as a square-root of squares. Below please see the equations for calculation of total noise for inverting and non-inverting configurations including the resistor thermal noise.
