Hi all,
few questions about op amp input noise and noise gain.
1) Given the input noise voltage
n (typically in [nV/sqrt(Hz)] ) if I want to know the noise voltage in output, I calculate:
n*sqrt(Bw)*Awhere
Bw is my bandwidth and
A the closed loop gain.
But what if I work only at one specific frequency
f*? Is it simply
n*A?
2) If
n is not constant but changes with the frequency (for example see
Figure 11:
https://www.apexanalog.com/resources/products/pa90u.pdf), and I work in the range, say from 10 Hz to 1kHz then I need to
integrate the input Noise Voltage curve given in the datasheet over the operating frequency range, correct?
3) The noise gain.
The AD Tutorial (page 3:
http://www.analog.com/media/en/training-seminars/tutorials/MT-033.pdf) says that: "
Noise gain is equal to the signal gain of a non-inverting amp. Noise gain is also the same for either an inverting or non-inverting stage. ".
So, in case I am designing an
inverting op amp, by which gain do I need to multiply the noise? Non-inverting gain?
Thank you