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A simple model of a transistor/LED/photodiode

  1. May 21, 2009 #1
    any objections to using this simplified model to explain current amplification to beginners?

    "A simple model with many of the properties of a transistor, especially a phototransistor, is a forward biased LED (emitter–base junction) and a reverse biased photodiode (base–collector junction) sharing an anode (base) in a single package so that 99% (1-1/βF) of the photons emitted by the LED are absorbed by the photodiode. Each electron-hole recombination in the LED produces one photon and each photon absorbed by the photodiode produces one electron-hole pair therefore each electron injected into the base, and therefore the LED, would result in 100 (βF) electrons at the collector"

    this explanation was directly below the section starting with:
    "An NPN transistor can be considered as two diodes with a shared anode region"

    for reference:
    Last edited: May 21, 2009
  2. jcsd
  3. Aug 20, 2010 #2
    apparently such a device is called a "photon coupled transistor"
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