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Amplifier required for HARLID and LLAM-1060-R8BH (APD)

Bivin George
Expert 1047 points
Other Parts Discussed in Thread: LOG112, LOG101, OPA820, VCA821, OPA842

I'm looking for an amplifier which satisfy the following specs :

1) Output current of detector will vary between 10nA to 150mA

2) Minimum Pulse width (ON Time) will be 5ns.

3)Pulse repetition frequency will be between 1Hz to 10KHz

Please go through the data sheet for both detectors for further information.

Please suggest some techniques to measure such wide varying current pulses.

  • 0
    TI__Genius 12631 points

    Hello Bivin,

     For a range that large a log-amp (LOG112, LOG101) is the best solution. Unfortunately we do not have any high-speed log amps in our portfolio; they are mainly precision type amplifiers.

    There are two choices -

    1. Build a discrete amplifier using some of the suggested circuits show in this app. note and the log112 datasheet

    2. Use a high speed amplifier like the OPA842 or OPA820 and follow this up with a variable gain amplifier such as the VCA821. This is not the optimal solution for SNR. Ideally most of the gain should be at the front-end of the signal chain for improved SNR.

    3. Use relays/switches and multiple amplifiers in parallel and depending on the expected signal range select the appropriate amplifier chain. Alternatively you could also use the relays/switches directly in the feedback path of the transimpedance amplifier.

    -Samir

    -Samir