Stretching short pulse

Thread Starter

Pinkamena

Joined Apr 20, 2012
22
Hello everyone.
What would be the easiest way to stretch a short DC pulse (100ps-3ns) to a relatively longer pulse of 50ns with minimal delay(<1ns)? The device or circuit should be ready within at least 10ns to receive a new pulse to stretch. The signal type is ECL.

Thanks for any suggestions!
 

Papabravo

Joined Feb 24, 2006
12,405
The type of circuit you are looking for is called a one-shot. The real problem with using them is that the location, in time, of the trailing edge is not very precise AND is it not synchronous to anything.
 

crutschow

Joined Mar 14, 2008
23,349
The only thing I could come up with is to use a fast ECL FF such as this, with D set to logic high and the pulse going to the clock input.
Feedback from the Q output through a 50ns time-constant RC delay network to the Reset input would give the stretched pulse at the output.
But the fastest clock input is a little over 3 GHz so it may not respond to an input pulse less than about 160ps.
 

Thread Starter

Pinkamena

Joined Apr 20, 2012
22
The only thing I could come up with is to use a fast ECL FF such as this, with D set to logic high and the pulse going to the clock input.
Feedback from the Q output through a 50ns time-constant RC delay network to the Reset input would give the stretched pulse at the output.
But the fastest clock input is a little over 3 GHz so it may not respond to an input pulse less than about 160ps.
I can live with a minimum pulse width of 160ps. Thanks for the suggestions, I will look into this.
 

crutschow

Joined Mar 14, 2008
23,349
You may need a fast Schottky diode across the Reset resistor (cathode to output) to get the 10ns recovery time you want.
 
Last edited:

DerStrom8

Joined Feb 20, 2011
2,373
Why not use a 555 timer in one-shot mode? The short pulse triggers the 555, the on-time from the output is set by the capacitor and resistor values.
 

crutschow

Joined Mar 14, 2008
23,349
Why not use a 555 timer in one-shot mode? The short pulse triggers the 555, the on-time from the output is set by the capacitor and resistor values.
Did you notice the pulse widths involved?
I seriously doubt that you can get a 555 to trigger from a sub ns pulse or generate a 50ns output. :rolleyes:
 
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