op amp voltage follower

This is a super short video on the functional use of an op amp voltage follower (buffer) circuit. More detailed info is available at www.ece.utah.edu/~ece1250

>> In this video, I would like to summarize the function

of the voltage follower or unity gain buffer.

This is basically a non-inverting amplifier with a gain of one.

We run our feedback loop again from

our negative terminal directly to our output voltage like so,

and then will often have a load resistance down from our output voltage.

So, there's our feedback loop,

it's connected directly to V0,

and we're going to put our source on

this other side. Plus minus Vs and Rs that's going into the positive terminal.

In this case, V0 is equal to Vs. Now,

I would want to do such a thing,

we already have Vs on the side.

The main reason is because the current that is going into this terminal is equal to zero.

So, I can put any system over here such as a voltage divider or any other voltage system,

may be a sensor bridge,

and not the impacting the circuit on this side.

This is completely isolated from this side.

No current passes from my input circuit to my output circuit,

and that's why we use this buffer.

So, we have V0 is equal to Vs.

If we wrote that in terms of gain,

we would say that V0 is equal to the gain times Vs,

and in this situation gain is equal to exactly one.

We could also draw a picture like so,

where we can say that Vs was coming in being multiplied by one and coming out as V0.