I did the following modification in the schematic, so no more overshoots now. ]
The resistor is 47 ohm, the capacitor is 10 nF
The current input of the switch is almost zero.
I'm working with analog devices adg419
http://www.analog.com/static/imported-files/data_sheets/ADG419.pdf
The problem is the frequency.
Now with arduino duemilanove I'm working @ 10 khz but in future I will arrive at 1 mhz or more, so don't know if this is the right switch design for HF.
The biggest trouble now is the op-amp : it works perfectly for 10 minuts and after go on strike!
I have already burned two. =( =( =(
So, where is the problem now?
Anyway, I solved the problem of topic : I NEED THIS RC NETWORK.
100000 thanks 8)