Diodes across op amp input

[WGTP]

I have seen several designs lately with diodes between the + and - inputs of an op amp.  What's up with that? 

[davebungo]

It's protection against the inputs becoming too far separated in voltage which they generally do not like i.e. it can kill the input of the device.  Most devices these days have built in protection so it may not be necessary to have external diodes at all.

[R.G.]

Read GEO.

"What are all those parts for?"
and
"When good opamps go bad"

They are indeed for protecting the inputs, but just diodes there will not do the trick. Some opamps have them built in to the inputs.

[WGTP]

Just wanted to make sure it wasn't another clipping opportunity.