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How to generate a width of 500 picosecond pulse?

Discussion in 'Electronic Design' started by [email protected], Jan 5, 2006.

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  1. Guest

    How to generate a width of 500 picosecond pulse?
     
  2. Andrew Holme

    Andrew Holme Guest

    Use a step recovery diode.
     
  3. John  Larkin

    John Larkin Guest


    What's the input, and what sort of load do you want to drive?

    John
     
  4. Phil Hobbs

    Phil Hobbs Guest

    Two inches of coax with a short at one end. Drive with a fast edge,
    e.g. from a step recovery diode.

    Cheers,

    Phil Hobbs
     
  5. John Fields

    John Fields Guest

     
  6. John  Larkin

    John Larkin Guest

    3"

    John
     
  7. John Larkin wrote...
    2" :)
     
  8. Al

    Al Guest

    Nah, start with 1 foot of coax per nanosecond. Then keep trimming it
    down until you get what you need with your load.

    Al
     
  9. John_H

    John_H Guest

    (pssst: The speed of light in coax is about 2/3 C or about 7.8 in/ns)
     
  10. Joerg

    Joerg Guest

    Hello Al,
    But be careful and mind what's in the direction where the coax snippet
    flies. I have seen a guy do exactly that job with this stiff mil-spec
    coax. One piece flew right through a vent hole into a scope. Bzzzt ...
    poof. About $2000 worth of damage according to the repair invoice.

    Regards, Joerg
     
  11. Thougth the speed of light was metric these days?


    martin
     
  12. John Larkin

    John Larkin Guest

    Why do you think they call Paris "the city of light"?


    John
     
  13. Mike Young

    Mike Young Guest

    Cheaper than putting out an eye. :0
     
  14. Joerg

    Joerg Guest

    Hello Mike,

    True. That's why I wear goggles/glasses when doing such work. Same when
    I get a clients prototype and there are tantalums on it.

    Regards, Joerg
     
  15. I gave that as an answer in a test once, long ago and failed. The "correct
    answer" was a one shot made with 2N2222's operating at <1.0mA currents.
    Who knew!
    Harry
     
  16. Fred Bartoli

    Fred Bartoli Guest

    Sure, but without a scope you're blind too.
     
  17. Gerhard

    Gerhard Guest

    See Linear Technology www.linear.com Application Note 47
    'High Speed Amplifier Techniques' (page 93), for a discussion and
    circuit using one of the techniques to generate less than 1ns pulses.

    Linear Technology AN47, by Jim Williams, is a very good paper that
    discusses in detail the precautions and pitfalls required when working
    with very fast pulses and pulse edges. It contains lots of information
    that details design, bread boarding and measurement techniques,
    complimented by many circuits and scope trace photos.

    Gerhard van den Berg
     
  18. Gerhard

    Gerhard Guest

    See Linear Technology www.linear.com Application Note 47
    'High Speed Amplifier Techniques'(page 93), for a discussion
    and circuit that employs one of the techniques to generate
    less than 1ns pulses.

    Linear Technology AN47 by Jim Williams is a very good paper
    that discusses in detail all the precautions and pitfalls of
    working with very fast pulses and pulse edges. It contains
    extensive details on design, bread boarding and measurement
    techniques, complimented by many circuits and scope trace photos.

    Gerhard van den Berg
     
  19. Robert Baer

    Robert Baer Guest

    What about reflection doubling the length, and what about the fact
    that waves travel slower in coax than in vacuum/air?
    Methinks Mr. Hobbs was a lot closer to the correct length of coax.
     
  20. Robert Baer

    Robert Baer Guest

    Well, that takes care of the reflection, but...
     
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