Help!!! AC-coupling for Laser Driver

Discussion in 'General Electronics Chat' started by Rattapoom Tidprom, Jul 14, 2015.

  1. Rattapoom Tidprom

    Thread Starter New Member

    Jul 14, 2015
    3
    0
    I'm starting to understand laser driver (especially Maxim laser driver). I'm having a hard time to understand why we have IL = IBIAS + IMOD/2 when optical high output and IL=IBIAS-IMOD/2 when optical low output. (IBIAS and IMOD are constant current sources). I've also attached the article that you can find the basic details about interfacing with Maxim laser driver.

    upload_2015-7-15_9-33-55.png
    upload_2015-7-15_9-34-35.png
    upload_2015-7-15_9-35-10.png
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  2. #12

    Expert

    Nov 30, 2010
    16,261
    6,774
    The bottom, right drawing seems to illustrate why AC coupling causes a +/- effect with the modulating signal. I think you merely overlooked the idea of AC coupling making the modulating signal cause both greater and lesser excursions of the bias current across time.
     
  3. Bordodynov

    Active Member

    May 20, 2015
    637
    188
    hope you will help my calculation. I found that the average current through the inductor is equal to half. See my chart.

    Laser_AC_Mod.png
     
  4. Rattapoom Tidprom

    Thread Starter New Member

    Jul 14, 2015
    3
    0
    @Bordodynov - How can get plight from LTSpice? Can you take the snap shot? I'm trying to learning from simulator also.
     
  5. Rattapoom Tidprom

    Thread Starter New Member

    Jul 14, 2015
    3
    0
    Is it additional library for laser diode?
     
  6. @Bordodynov Could you show me step-by-step for your simulator? i need to learning for usage this simulator. thank you.
     
  7. Bordodynov

    Active Member

    May 20, 2015
    637
    188
    Last edited: Jul 16, 2015
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