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  1. #1
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    In IO pad, why do we need a floating Well?

    A lot of IO design use floating Nwell on the PMOS output transistors. For input IO cell, I guess this is to do with 5V tolerance. But why do we need a floating Nwell in output cells.
    Any one got a clear picture on this issue?

    •   Alt13th August 2004, 11:53

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  2. #2
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    Re: In IO pad, why do we need a floating Well?

    For 3.3Volt logic IO,s that need to be 5Volt tolerant, a way of ensuring that the PMOS gate oxide never sees 5.5Volts across it is to use floating wells.



    •   Alt15th August 2004, 17:47

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  3. #3
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    Re: In IO pad, why do we need a floating Well?




    •   Alt16th August 2004, 05:30

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  4. #4
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    Re: In IO pad, why do we need a floating Well?

    For protecting the bonding wire connected with sub when bonding



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