Stretching short pulse

Discussion in 'General Electronics Chat' started by Pinkamena, Nov 11, 2015.

  1. Pinkamena

    Thread Starter New Member

    Apr 20, 2012
    22
    4
    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!
     
  2. crutschow

    Expert

    Mar 14, 2008
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    What is the ECL type that is generating the pulse?
     
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  3. Papabravo

    Expert

    Feb 24, 2006
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    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.
     
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  4. crutschow

    Expert

    Mar 14, 2008
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    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.
     
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  5. Pinkamena

    Thread Starter New Member

    Apr 20, 2012
    22
    4
    I can live with a minimum pulse width of 160ps. Thanks for the suggestions, I will look into this.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    You may need a fast Schottky diode across the Reset resistor (cathode to output) to get the 10ns recovery time you want.
     
    Last edited: Nov 12, 2015
  7. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    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.
     
  8. crutschow

    Expert

    Mar 14, 2008
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    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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  9. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Woops, guess I wasn't really thinking :p
     
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