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photodiode amplifier

Yung-Cheng
on Jul 15, 2015

Dear all

I want built a photodiode amplifier.Its bandwidth need over 100MHz to observe a pulse train.

I use photodiode wizard(PHOTODIODE | Analog Devices) and follow their suggestion.

But I test the circuit and there's a strange oscillation(as attachment) and exist when I block my photodiode.

How to solve this problem?

attachments.zip
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    •  Analog Employees 
    on Jul 16, 2015 4:50 AM over 5 years ago

    Hi Yung-Cheng,

    The AD8015 may be a good option, but I am curious why the circuit the photodiode wizard generated for you using the ADA4899-1 and AD8011 is not working for you.

    Some questions that might help to debug the circuit:

    1) Are the power supplies for the ADA4899 and AD8011 bypassed with 0.1 uF capacitors?

    2) What does the signal at the the ADA4899-1's output look like?

    3) If you remove the photodiode completely from the circuit, does the oscillation go away?

    4) Can you double check that Cf, the 3.9pF capacitor, is indeed soldered correctly?

    5) If you change Cf to a larger value, say 10 pF, does the oscillation change?

    Thanks,

    Matt

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  • 0
    •  Analog Employees 
    on Jul 16, 2015 4:50 AM over 5 years ago

    Hi Yung-Cheng,

    The AD8015 may be a good option, but I am curious why the circuit the photodiode wizard generated for you using the ADA4899-1 and AD8011 is not working for you.

    Some questions that might help to debug the circuit:

    1) Are the power supplies for the ADA4899 and AD8011 bypassed with 0.1 uF capacitors?

    2) What does the signal at the the ADA4899-1's output look like?

    3) If you remove the photodiode completely from the circuit, does the oscillation go away?

    4) Can you double check that Cf, the 3.9pF capacitor, is indeed soldered correctly?

    5) If you change Cf to a larger value, say 10 pF, does the oscillation change?

    Thanks,

    Matt

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