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For a project, I will be using a Avago 2310Z photodetector.

When I went through the datasheet, I could not find the sensitivity mentioned

I also looked through couple of datasheets from other companies, but could not find sensitivity mentioned.

Sesitivity parameter is needed to perform power budget analysis in an optical link.

How is it calculated?

Here is the link to datasheet.

http://www.avagotech.com/products/industrial-fiber-optics/industrial-control-general-purpose/1300nm/afbr-2310z#documentation

Regards, Abhilash

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    \$\begingroup\$ "200 V/W typical conversion gain" ? \$\endgroup\$
    – Icy
    Commented Aug 12, 2016 at 10:04
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    \$\begingroup\$ ...+-2dB it seems \$\endgroup\$
    – Vladimir Cravero
    Commented Aug 12, 2016 at 10:14

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The sensitivity depends on how you use the device.

Sensitivity is the minimum input power to obtain a specified bit error rate (typically between 10-15 and 10-9) in an optical communication system.

The sensitivity depends on the receiver characteristics, but also on the modulation scheme and any data encoding used in the system.

You can tune the sensitivity by low-pass filtering the output of this device. But the bandwidth of the LPF that you can usefully apply depends on the bit rate of your communication system. Once you determine the filter bandwidth you're going to use, you can estimate the sensitivity from the noise characteristics of the receiver, specified as an input-referred noise in the datasheet:

enter image description here

To roughly estimate the sensitivity, multiply the input-referred noise by the square root of your system noise bandwidth (hopefully mainly determined by the filter bandwidth). If you are using on-off keying (OOK) with no error-correcting codes, you'll need an input optical modulation amplitude of at least about 12x (IIRC) this value to achieve a 10-9 BER in your system.

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  • \$\begingroup\$ Yes, I think this is a better answer than mine but I will say that you can't obtain a sensitivity figure from the data sheet without knowing the final noise bandwidth of the system so maybe the OP needs to figure out what he is expecting the data sheet to say +1 \$\endgroup\$
    – Andy aka
    Commented Aug 12, 2016 at 17:05
  • \$\begingroup\$ @Andyaka, good point, edited to use the term noise bandwidth. \$\endgroup\$
    – The Photon
    Commented Aug 12, 2016 at 17:24
  • \$\begingroup\$ Thanks, points noted. I have some more questions, 1. The 3 dB bandwidth is given in the datasheet. Is it for photodetector or the amplifier ? 2. Is the amplifier a Trans-impedence Amplifier (TIA) ? \$\endgroup\$
    – Abhilash A
    Commented Aug 16, 2016 at 6:12
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The important parameters are: -

  • conversion gain = 200 volts per watt
  • maximum input optical power = - 2 dBm

So, a signal light power of -2 dBm = 0.63 mW and this would yield an output signal of 0.126 V rms (based on 200 volts per watt).

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    \$\begingroup\$ This tells you the responsivity of the receiver, not the sensitivity. Sensitivity depends on the receivers noise characteristics. \$\endgroup\$
    – The Photon
    Commented Aug 12, 2016 at 16:04
  • \$\begingroup\$ @Photon . Conversion gain for photodetector is understood. In the Laser datasheet, the conversion gain is given to be 20 mW/V and there is an amplifier before the Laser. what does this value mean? What type of amplifier is it (voltage amp, TIA, Transconductance)? Here is the link to Laser's datasheet. avagotech.com/docs/AV02-3184EN \$\endgroup\$
    – Abhilash A
    Commented Aug 16, 2016 at 6:38

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