Signal Choppers

Basically signal choppers are circuit that limits the voltage to a predetermined value.
And I don't think it's related to any thing since SS diodes can be used as signal choppers too.
Say if u put 2 silicon diodes back to back across a sine wave source the out put will be reduced to the forward voltage drop of the diodes, like 0.6 from either side.
Any increase in the AC voltage will not be reflected at the output where the diodes are connected. but will be limited to the diode voltage.
So if FET's are used, one can design the FET biasing so that the FET turns on chopping the output top any value you require.
Get the point

thanks!!.........