I'm trying to understand the concept of negative feedback in an op-amp. I've read the wikipedia article and the allboutcircuits article and have a couple of questions.
If you have 2 inputs, and inverting and non-inverting, the ouput will be the polarity of whichever one has a higher voltage(if no negative feedback is used). Basically if the non-inverting has a higher voltage the output is positive and the out voltage will be whatever v+ is. This happens because the gain is so high it saturates easily.
Hopefully that is right.
Then it gets muddy when it comes to negative feedback. Why does the output "follow" the input? If both the inverting and non inverting inputs are the same voltage shouldn't the output be 0V?
The way I see it. If the non-inverting input is 5v and Vin+ is 15v. The output will be 15V and than negative feed back into the system making the non-inverting ouput higher and switch Vout to Vin-.
I just need a good explanation of how the negative voltage works.
If you have 2 inputs, and inverting and non-inverting, the ouput will be the polarity of whichever one has a higher voltage(if no negative feedback is used). Basically if the non-inverting has a higher voltage the output is positive and the out voltage will be whatever v+ is. This happens because the gain is so high it saturates easily.
Hopefully that is right.
Then it gets muddy when it comes to negative feedback. Why does the output "follow" the input? If both the inverting and non inverting inputs are the same voltage shouldn't the output be 0V?
The way I see it. If the non-inverting input is 5v and Vin+ is 15v. The output will be 15V and than negative feed back into the system making the non-inverting ouput higher and switch Vout to Vin-.
I just need a good explanation of how the negative voltage works.