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I am very new to LTspice. I would like to ask "How can I add a photodiode in the Ltspice?" Is ideal photodiode (or any specific) model already included in the LTspice or do I need to create third party model for photodiode? If it is already included, under with categories it is included in library ? Or If it is not included, how can I make one? Do I need to create the spice model of photodiode which will consist (roughly) of a current source, capacitor and resistor then refer back to the photodiode? Or if there is another way around can you please share your knowledge?

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  • \$\begingroup\$ LTSpice doesn't model optical events, perhaps model it as a programmed current source? \$\endgroup\$ – Jasen Jun 20 '16 at 7:37
  • \$\begingroup\$ ahhh.. I see. So I can use a current source (may be in parallel with capacitor) instead of photodiode? \$\endgroup\$ – Sui Jun 20 '16 at 7:49
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The easiest way to get a photodiode, and to control it, is to use one of the built-in optocouplers. The base/collector junction of a phototransistor is a photodiode (just ignore the emitter):

optocoupler as photodiode

Or use the 4N2x.sub/CNY17.sub as a model to build your own subcircuit.

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Another way is to find a photodiode model on the internet as the .SUBCKT model. You can add such a model directly to the diagram and connect it under the diode symbol.

On my blog it is more visually described:

http://sigaris-electronics.eu/2018/11/ltspice-adding-an-element-model-to-the-schema/

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