On 12/26/13 8:07 AM, ct1dmk wrote:
Hello,
I'm willing to generate a pulse (of some few hundred volts)
by discharging a capacitor into a pulse transformer
I'm solely interested is the active edge (call it either rise or fall
depending on the
wiring of the output of the transformer).
ns risetime pulses sounds like fairly straight forward radar stuff.
the inductance of the transformer is going to be your challenge,
depending on the energy level. What about a non-transformer
alternative? Can you just charge your cap up to the few hundred volts
and have a switch that can take the voltage?
How much energy do you need? You said a few hundred volts, but is that
microjoules, joules, or kilojoules?
A small triggered spark gap would be one way. There's also the ever
popular krytron, which has very good timing accuracy.
YOu might look for circuits used for exploding bridge wires (EBW)
The target is 4ns, while ideas seemed to be clear at some point, now I'm
having doubts if better to use a MOSFET or a bipolar transistor
as the switch element. Experiments with MOSFETs presented me some
difficulties charging the gate capacitance having some trouble to
achieve something in the 4ns region. Well 4ns seems hard whatever device
anyway.
You want some sort of RF transistor here. What about one of the new
LDMOS FETs: some have fairly impressive voltage handling, and if they
work at 1 GHz for radar applications, they will work for you.
What about stacking a bunch of MMIC RF amplifiers (e.g. like the ERA or
GAL from minicircuits)
Other traditional approaches to fast pulse generation are avalanche
transistors.
There's also a variety of interesting pulse forming networks that can
generate fast rise time high voltage pulses. Blumlein arrangements are
one. Your 100ns pulse is fairly long for a transmission line scheme,
though (20-30 m of coax)
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
