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HOW to generate controllable short pulse?

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ljkong

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zetex avalanche pulse generator

for examle: 0.2 ns pulse.
i know some circuit can generate 0.2ns impulse.
but how to generate a controllable impulse?
in impulse radio communication, how do they generate?
thanks.
 

transmission lines

This is usually done with transmission line networks. The problem is triggering the circuit. You need a semiconductor that can switch state in less than this time.
 

Such generators uses tunnel diode and transmmision line network. Tunnel diodes can have rise time less than 20ps.
 

thanks.
but. how can i control the pulse? for example, when PPM, how to
use the data to control the pulse?
is it easy or difficult?
 

Some generators use AVALANCHE transistors to generate very short pulses
like GPR! Look in patent database for Mr. Morey's patent about transmitter
for GPR with 2n2222!
Try this also: **broken link removed**
Best, :)
 

ljkong said:
for examle: 0.2 ns pulse.
i know some circuit can generate 0.2ns impulse.
but how to generate a controllable impulse?
in impulse radio communication, how do they generate?
thanks.
Click to expand...
step recover didoe

lokk for comb generator at this site
 

can someone upload that patent paper??

I haven't found in the web.

Best regards,

mimoto
 

Hi,
Tthere is patent:Geophysical Surveying System.....
A geophysical survey system repetitively transmit 1nS short impulse in the ground.
Inventor: Mr. Rexford Morey from Geophysical Survey System Inc- manufacturer of SIR ground penetrating radar.
 

One student in our lab just submitted a couple of papers on tunable pulse generator design (sub-nanosecond).

The power efficiency is not good.
 

Hi ljkong,

Can you post some short pulse generator circuits in here? Because i need to generate pulses with duration about 500ps. Thank a lot.


Best regards.
 

You can generate easily les than 100ps rise time pulses with SRD (Step Recovery Diode).
If you apply this pulse to a transmission line ended with short circuit, when the reflected pulse comes back it zeros (almost) out the pulse.
Such way you can get about 100ps or longer pulses.
When moving the short circuit farther from the source the pulse is widening.
You can make shorts by PIN diodes on different length and so pulse width can be changed.
Look about SRDs in @gilent homepages and literatures.
 

Hi g579, Thanks for your suggestion. But, is it possible to use transistor (with high transition frequency) to generate less than 500ps pulses? Can anyone post any related informations here? Thanks you.

Best regards.
 

hi mac7879,
sorry, i do not have those reference circuit until now.
good luck
 

I want to generate controllable short pulse, too, from 1ns to 20ns
 

it can be done with step recovery diode. Try google: SRD PPM and you will find some pdf's.
 

maybe this file can help you
 

http://www.springerlink.com/(ncjzb5j15z0ybeujuufm1s55)/app/home/contribution.asp?referrer=parent&backto=issue,25,35;journal,205,507;linkingpublicationresults,1:106484,1
 
One could control short pulse duration from 0-10ns (or more) in 10ps resolution using the programmable delay chip and a high-speed XOR gate...
 
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