Hello, I'm using an AD8397ARDZ to make a simple, fast buffer capable to drive 50 ohm loads at 0-5V:
The input is a 0...3.3V HCMOS square wave at 10 kHz.
What I'm experiencing is a "tail" on the falling edge of the output waveform:
I suppose this is due to the common emitter output stage.
Is there a way to improve this behavior, apart from using a dual supply voltage (which I cannot do)?
I've tried to reduce the resistor values (the screenshot actually refers to the configuration R3=R4=220 ohms) but the improvement is quite small.
Using the opamp in open loop improves things:
The falling edge when zoomed is still a little bit ugly, but it should be ok:
The configuration works as Comparator.
Your reference is 2.5V.So that is, if your input is 3.3V which is higher than your reference, you got a 5V output.
You might want to consider a comparator in your application.