How about two diodes + wire?
I don't know how to attach a simple picture here so the text follows:
D1 sees signal first, Delay line end 1 also tied to diode1 input side
Other end of delay line goes to D2 input
D1 & D2 are tied together to form a "dot and" circuit. The output level=20
is dependant on both diode inputs.
The delay line: If you run the numbers you will find that the speed of=20
light is a little less than a ns per ft. That is true for a signal in a=20
wire as well. Roughly, a foot of wire is a ns of time. However, coatings=20
on the wire introduce a velocity factor which slows down signal.

On 7/4/2013 1:41 PM, Yigit Turgut wrote:
> Hi collective brain,
>
> I want to generate a pulse/square signal with a few nanoseconds of
> rise/fall times. I did this with various PIC's and with FPGA's and I got
> around 2ns of rise/fall times which is good but I need to make it simpler
> (cheaper).
>
> Now I am trying to implement the same with completely analog components ;
>
>   width ; adjustable between 2ns-10ns
>   frequency ; adjustable between 1Hz-200Hz
>   amplitude ; adjustable between 5V-12V
>
> I know there are some defacto ways to do this but I feel rusty on the
> analog side and would appreciate the guidance of analog experts here. I
> know you are out there, don't hide!
>
> Yigit

--=20
John Ferrell W8CCW
"The pessimist complains about the wind;
The optimist expects it to change;
The realist adjusts the sails."
      William A. Ward


--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.