This circuit presents how to detect generator voltage sign (+/- - negative/positive op-amp output voltage) in reference to some other voltage (in this example generator voltage is referenced to 2.5V measured from the ground) without overloading op-amp. Op-amps can work faster without overloading them. I set diodes junction capicitance to 20 fF which I don't know if it is possible in any diodes. I heard that shottky diodes can work at very high frequecies but they are not present in everycircuit, they also have lower voltage drop on them.
