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GAAS chips overvoltage protection

Discussion in 'Electronic Design' started by Slav Mitrofanov, May 21, 2004.

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  1. Good day, dear community. There is a little problem and hope someone may
    guide me to a solution. I have got active antennas switced by a GAAS chips
    (like HMC336MS86 or SW338) I want the chips be protected from ESD and
    probably wrong conection (between devices wich may have different woltage at
    their GND pins. There are two solutions I have got:: back reversed diodes
    and special 0603 SurgeX devices from Cooper Bussman.But the trigger voltage
    for them is 100V and clamping voltage is 35 V. Will it protect my chips? Can
    anyone recommend me a literature to read? Datasheets for thechips limits
    only the max power, not voltage...
    Thanks in advance.
  2. Joerg

    Joerg Guest

    Hi Slav,

    The usual method of one diode to the supply and one to ground might work. You
    can get fast double diodes in SOT23 pack so you'd only need one device. It
    depends on what input levels can be tolerated.

    Back to back diodes can introduce intermodulation if this is a receiver circuit.

    Regards, Joerg
  3. Hello, Joerg!

    Thanks for replying. Sometimes a simple question might be a problem. In this
    case I just have a huge desire to use the new (for me) component - the
    COOPER Bussmann ESD 0603eESDA SurgeX technology) It is just one 0603 chip
    which has 0.2 pF capacity and extra high resistance. at the 100 V it
    triggers and in 5 nS the voltage is around 35V. I just do not know if that
    is ok for the chips I mentioned.

    Thanks for the information about your site. Have a brief look at it . Hope
    one day will apply officially for help.

    Best regards.

    p.s. Sorry e-mail you mentioned is not available for my provider.
  4. Joerg

    Joerg Guest

    Hi Slav,

    Just make sure that these remaining surges are ok with your GAAS chips. I don't
    know the Bussman devices but a remaining 35V after 5nsec (that's a really long
    time for GAAS) could be too much. Best is to check the data sheet for absolute
    maximum ratings. But again, it could be that 5nsec of surge is still too much
    and this could damage the chips. Sometimes that damage is partial which means
    the GAAS chips might still work but not up to specification anymore. That is
    like in a boxing ring where the chips get hit again and again, become worse in
    performance over time and after too many hits they'll give up.

    A nice pair of Schottky diodes is usually best but of course that will add
    capacitive load.

    Email: Just delete the parts "notthis" and "removethis" and it'll work. Or use
    the one on my web site. Sorry for that but it is about the only way to avoid all
    this junk email from people selling medicine and other stuff that I don't need.

    Regards, Joerg
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