[time-nuts] fast edge, rise time.

[ct1dmk]

Many thanks to all for the nice tips.

I may narrow down by saying a few more specs as suggested.
The pulse would see a somehow unknown load but for a start I
was suggested to have my source with 50ohm impedance so worst
case would be a short circuit and therefore the pulse would be a current 
pulse
and would have some 10Amp. Pulse length about 100ns so only some 0.5mJ 
energy that would die inside the pulse source( this would be the worst 
case).
The 100us repetition rate make a a very small duty cycle of 1/1000 so 
average power
maximum 5W.

Since the amplitude and timing parameters are to be controlled (pulse 
timing come from an FPGA) I really need a solution using that trivial 
switching element fet or bipolar (and can't really do a more exotic 
scheme if I cant electronically control the parameters) also I must use 
a transformer because these short pulse are to be superimposed to 
another voltage and a transformer becomes very handy to do that. I 
interrupt the wire and insert the secondary there to add the pulses.

The challenge I'm facing is on the device either RF FET or Biplolar tr 
etc. and
surrounding circuits, transformer, etc. this to achieve the 4ns (or 5ns).
(the transformer I have in mind is something very similar to those 
transformers
on the final stages of HF/VHF ham radio amps, coax cables and ferrite cores)
any suggestion regarding devices etc ?...

Thanks for all comments.

Luis Cupido.