Some questions about OP-Amp

[belal elkady]

-what is the benefit of differential Amp and comparator ?
-why logarithmic amplifier better than normal amplifier?
-how schmitt trigger overcome noise?

 

[Miguel Gaspar]

The differential amp has two modes of operation:
Common mode imput, that is the same signal gets to both input, and the common gain≈ 0
Differential mode and the whole signal gets to one input with respect the other, and the gain » 0.
So you can eliminate the signals that comes in common mode and amply the differential ones.

For the second it depends the aplications in some cases log amp are better. For example the smith trigger require comon opamp and not log amps.

The schmit trigger isa hysteresis comparator, two diferent points for comparing, one point to get high and the other to get down. So it gets a poitn to get high and a voltage margen to get down. When it get down it has a voltage margen to get up.

 

[belal elkady]

what are the buffer benefits ?

 

[Zanderist]

One thing I could tell you is that a comparator can only exist in two states, on or off, which is great for making bar graphs or angle indication for a ships rudder.

Texas Instruments put out a free booklet on Op Amps which you could find on Google 'Op Amps for Everyone'.