Amplifier Question

Thread Starter


Joined Oct 14, 2011
I got a question about amplifiers and noise. Does a inverting amplifier add more noise than a non inverting amplifier? My rails are +5V and -5V. The +5V has about 1mV or noise and the -5V has 2mv of noise.


Joined Nov 30, 2010
True. An op-amp, or any other well designed amp, will reject power supply ripple and noise by virtue of the configuration of the transistors.

For really nit-picking noise calculations, the input and feedback resistors are usually the major noise source.


Joined Mar 14, 2008
The intrinsic op amp input noise gain is amplified by the non-inverting gain or 1 + the inverting gain. Thus for a gain of 1 the inverting amp will have twice the noise gain for the op amp intrinsic input noise as the NI amp.
Edit: This is for the op amp input noise (in V/√Hz as given in the data sheet).