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IR receiver circuitry

Discussion in 'Electronic Components' started by bubbles123, Jun 28, 2007.

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  1. bubbles123

    bubbles123 Guest

    I'm trying to design the receiver circuitry for an IR link that
    detects 1MHz signals at least 70cm away. Currently I'm using an Optek
    photodiode (OP999) with OPA380 as my transimpedance amplifier, an op-
    amp after the transimpedance amp to further amplify the voltage and a
    comparator to reconstruct the transmitted signal.
    At the moment I'm just pulsing a 1MHz square wave through my IR
    emitter but the output from the transimpedance amplifier does not come
    out square! Can anyone suggest an IC transimpedance amp that will work
    for 1MHz signals across an IR link? (the OPA380 has a 1MHz bandwidth -
    hence the distortion at the output).
    Also, using just the OPA380 with a capacitor (to remove the varying
    offset) and a low pass filter I can meet the 70cm requirement. However
    with the op-amp and the comparator, I can only get about 20cm (if even
    that). Am I missing some fundamental component that is ultimately
    causing my receiver to fail?

    Any help would be greatly appreciated!!
  2. Salmon Egg

    Salmon Egg Guest

    Why do you expect the output of the IR source to follow the input waveform
    closely? It might, but that needs to be proven rather than assumed.

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