The GGPMOS diode vs. the GGNMOS diode in ESD protection

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chang830

Joined: 11 Feb 2006
Posts: 263
Helped: 11

21 Mar 2007 9:55 ggnmos

Hi,
In my ESD protection strategy, I used the GGNMOS diode and GGPMOS diode as my ESD protect circuit. The GGNMOS is from the pad to GND and the GGPMOS is from the PAD to VDD.

But some one recommend me to replace the GGPMOS diode with the GGNMOS diode and said it will play little function in ESD protection.

I want to know any guide line to use GGPMOS and GGNMOS in ESD protectiion from PAD to VDD?

PLs. comments.

hung_wai_ming@hotmail.com

Joined: 05 Jan 2004
Posts: 376
Helped: 39

21 Mar 2007 16:40 The GGPMOS diode vs. the GGNMOS diode in ESD protection

GGNMOS ideally works when IO zaps to VSS or VSS zaps to IO. GGPMOS ideally works when IO zaps to VDD or VDD zaps to IO. So, both should be placed on chip. GGNMOS should be more effective as it's mobility is higher for electrons than holes. However, as for this, gate length got to be thicker than PMOS gate length. GGPMOS can be of more current uniform.

I would say, GGPMOS or GGNMOS are both NOT effective. You should use resistive GGNMOS or resistive PMOS or pseudo grounded PMOS/NMOS as your ESD diode. I once implementted GGNMOS/GGPMOS and they CANNOT withstand over 2000V HBM, afterwards, I changed to resistive NMOS/PMOS and can withstand over 2000V, but still not much, at least may meet your requirement

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gafsos

Joined: 01 Feb 2006
Posts: 161
Helped: 11
Location: North Africa

21 Mar 2007 19:18 Re: The GGPMOS diode vs. the GGNMOS diode in ESD protection

hello,

Under normal operational conditions GGNMOS offers very high impedance and thus acts as an open. Under high current conditions, it is not the GGNMOS which turns on but the parasitic device present in the GGNMOS that turns on providing a very low impedance path. This property of the device is utilized for ESD protection.
GGNMOS function remains the same for grounded gate p-channelMOS transistor
ggPMOS. I joins hung_wai_ming(at)hotmail.com in his good explanation "both should be placed on chip"

SALAM
gafsos