| Electronics > Projects, Designs, and Technical Stuff |
| Looking for Cheap, Ultra Fast LEDs (2-3ns) |
| << < (3/12) > >> |
| Marco:
At least the bond wires will be shorter if nothing else. |
| moffy:
--- Quote from: supperman on January 26, 2020, 01:24:55 am --- --- Quote from: moffy on January 25, 2020, 11:03:00 pm ---This is a nice article about driving a blue LED with 1-2ns rise times: https://arxiv.org/ftp/arxiv/papers/1011/1011.1954.pdf Maybe some of the Broadcom HLMP devices would be suitable. --- End quote --- Thanks for that article. I had read it during my research. They don't mention the LED (from what I remember) and it is not real world (i.e. PSpice only). In the end it is about driving the LED with an OpAmp.. and at that speed and current that is super expensive for the OpAmp. My circuit will pre-load (keep the LED off but warm) then spike it positive or negative on a change in on/off state for under 1ns. The circuit is about $0.35 right now + LED. Mainly just looking for actual LEDs that are fast.. in the 650-950nm range.. 800ish preferred. --- End quote --- They do verify their PSICE model with actual measurements, at least voltage rise and fall. The opamp is just providing a very fast, high current pulse (there is no feedback except for voltage gain). You just need a push/pull output stage to source/sink the current. Lots of ways to do that cheaply. The LED is mentioned in the appendix: The datasheet for the HLMP-CB15-P0000. It is referenced along with the datasheet for the opamp. Unfortunately it is obsolete but you should be able to find an equivalent. :) |
| ali_asadzadeh:
Interesting topic, what do you want to do with these leds? If you found good sources in china please share :-+ |
| Marco:
--- Quote from: moffy on January 26, 2020, 06:38:48 am ---They do verify their PSICE model with actual measurements, at least voltage rise and fall. --- End quote --- The problem is that until the entire junction is filled/swept-out the current doesn't equal the optical output, so electrical response isn't all that relevant. |
| OwO:
Ordinary blue LEDs (usually GaN based) will all go to a few hundred MHz easily from my tests. What you want to do is bias the LED to half the operating current and measure the small signal impedance, like so: Then tune out the reactive portion and drive it with a wideband MMIC. |
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