I am trying to produce voltage pulses with very short rise time (<15 ps), medium width (20 ns) and amplitudes up to 15 V. As a promising candidate I selected photoconductive switches and ultrafast photodiodes. However, I have limited knowledge about electronics at all and thus, even less knowledge about these devices. Do you think it is possible to produce pulses like that by applying a constant bias DC voltage (for example 15 V) to the switch/diode and send a laser pulse with approx. 20 ns width to the photosensitive area?

I already found photoconductive switches at Hamamatsu and Laser Quantum that might work. In particular, I am talking about the G4176-01 and the Tera-SED3, respectively. However, I cannot imagine how to connect these switches. For the Tera-SED3, one would have to use the ground as the output but how to deal with the grounds than without violating the impedance?

I appreciate any help, advise, new insights and ideas. Also, if you know another supplier of photoconductive switches or photodiodes that might work for my purposes, I would be very grateful if you share these with me.

  • \$\begingroup\$ This diode is rated at 30ps which is beyond your spec. Do you need a latency lower than 15ps or the edge itself ? \$\endgroup\$ – Damien Oct 17 '18 at 13:23
  • \$\begingroup\$ You also need to consider into what kind of load you want to pulse \$\endgroup\$ – PlasmaHH Oct 17 '18 at 13:30
  • \$\begingroup\$ @Damien, yes that is right, but this photoconductive switch would be quite cheap and thus worth a test. With the Tera-SED3 I can go to 1 ps or below. And I am talking about the time from 10% voltage to 90% voltage. \$\endgroup\$ – Marv_92 Oct 17 '18 at 13:49
  • \$\begingroup\$ @PlasmaHH I will use a 50 Ohm coax as transmission line. However, I want to apply the pulses to a capacitor with approx 500 fF to 1 pF. But that is a different problem I think?! \$\endgroup\$ – Marv_92 Oct 17 '18 at 13:50
  • \$\begingroup\$ It seems to be quite hard to achieve, even the best buffer / driver are around the ns level. There are ultra fast op-amp able to drive at that speed but only up to 5V. \$\endgroup\$ – Damien Oct 17 '18 at 14:00

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