I have used integrators in the feedback loop of standard inverting and noninverting amplifiers to eliminate DC off-set at the output, the circuit Im talking about is something like this
I understand the function of the integrator, it samples the DC offset at the output and it starts ramping, the output of the integrator is feedback to the inverting input which gets added to the original offset but with opposite polarity, the integrator stops ramping (and stays there) when the offset at the output is zero.
Thats if we focus on DC, but what happens to AC?, imagine a 1KHz sine is inserted at the input, that means that the output of the integrator will be a cosine which is being fed back to the inverting input and added with the original signal. My question is: isnt this detrimental? I mean adding a cosine signal will affect the original AC signal (by a small amount), am I missing something?