inverting amplifier

It is programmed to have zero voltage gain.

Gain from the input resistor becomes zero. But, it turns into a non-inverting, unity gain amp relative to the plus input of the amp. Inverting gain = Rf/Ri = 0/Ri = 0. Non-inverting gain = Rf/Ri + 1 = 0/Ri + 1 = +1. Bob

Here's a place that will explain it to you:

Your text indicates the feedback is zero ohms, drop that into the equation for an inverting amp and get back to us.

You get a zero-gain inverter. I saw one of these in use once, and my engineer was baffled by it. "What the heck is a zero-gain inverter for?" and you could almost see the question marks around his head like in the cartoons.

It provides a virtual ground. I believe that the reason for doing it that way has something to do with temperature compensation or input offset current of the downstream devices.

Or, if you lift the non-inverting input, it's a voltage follower.

Cheers! Rich

It always amazes me... the little things you can learn from the most basic books and articles. Like... no one ever told me god created PNP transitors. Is this more persecution, Dr. Laura, and how should I smite them?

Seriously, I have a real basic book which wouldn't have taught me much except that it has a chapter on components. Different types of Rs, Cs, etc. Or there's my physics book that's short on words and big on equations contrasted with an EE series (9 volumes) which covers 1st year physics with more explanatory words. It just adds a bit.

Thank you everyone