Pulse Stretcher - V2

Update: kicad files: 2014-07-23-pulse_stretcher_kicad

A development on pulse stretcher V1.

This circuit is used to stretch a short 10 ns pulse from a photon-counting module to a 100ns long pulse that can be more easily recorded or time-stamped e.g. with the white rabbit fine-delay FMC.


The new circuit is the same LT1711-based design as the old one, with an added buffer (BUF602) on the output. This improves output-load handling because the BUF602 can drive both 50 Ohm and 1 MOhm loads.

The PCB is made to fit a BNC-BNC enclosure by Pomona.



Some testing with an artificial input-pulse from a Keithley 3390 signal-generator..


.. and with the actual PMT-pulse. Note how the 100MHz scope produces nice round smooth signals while the 500 MHz Tektronix reveals more of the ugly truth.


4 thoughts on “Pulse Stretcher - V2”

  1. Thanks, good job with kicad,
    Cans I ask you to send me this kicad project , I try to do the same thing with LTC6752
    Thanks you very much.

  2. I have update the post with a link to a zip file with the kicad project, schematic, and PCB. hope this helps.

  3. Hi! Thank you for posting this, I am also detecting optical signals and need to stretch the pulse for further sampling. I have a question: What happens if the amplitude of the incoming pulse changes? How does that reflect on the stretched pulse?

    Thank you.

    1. Hi Oscar, the comparator triggers and produces an output-pulse when the +input goes higher than the trigger-level set with the potentiometer on the -input.
      The output-amplitude will be constant for any input-pulse that causes the circuit to trigger. With a low amplitude pulse that stays below the trigger-level you get no output at all.
      In this sense all information about the input-pulse amplitude is lost, only timing information from the leading edge of the input-pulse is preserved (although there is some added delay through the stretcher ofcourse). Currently we use an ARTIQ DIO-card for time-stamping PMT pulses that go through this pulse-stretcher.

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