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power cut cells in ESD protection?

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katrin

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power cut cell

For the ESD protection, the technology provides I/O pad and Vdd, Vss pads
there are some power rings across these pads, vdd1, vdd2, vss1, vss2...
these Vdd1. Vdd2 should be connected together through the Vdd pad, the same for Vss

At the same time, I also noticed there are some cells called power-cut cells in the library. I may need to connect all these ESD pads together through these power-cut-cells(I am not sure)

Is it necessary to connect the ESD pads through the power-cut cells? Or can I use parallel metal to connect these pads together directly? can someone help me with that?
 

srieda

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what is power esd cells

power cut cells are used for power isolation. all power pads have mainly connectivity of various power lines and ESD structures. lets say, for example u need to separate digital and analog power supplies. then you insert a power cut cell so as to provide a 'cut' in the connectivity of the power pads.
hope this helps...
 

    katrin

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survivor

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esd consideration

If you have sensitive I/O pad for internal analog circuit, you may need to cut the I/O ring into 2 sections. One is for digital I/O and PWR/GND pads, the other is for analog I/O and PWR/GND pads. Each section with their own vdd1, vdd2, vss1, vss2,.... The reason for this is to prevent digital noise coupling from the digital I/O rail into sensitive analog circuit thru analog I/O pads.

Usually power-cut cell is used to connect the GND rail of I/O ring from both section for ESD consideration.
 

    katrin

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