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Reversed Biased Diode

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hrkhari

hrkhari

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Hi Guys:

When I submitted the GDSII file to the foundry, they feddback me in adding a reversed pn junction diode to GND at each gate transistor used. I thought adding a reversed biased diode to VDD and GND is only needed at the Input -Output of RF circuitry, please feedback whether it is advisable to add the pn junction at the gate and Why?..Thanks in advance

Rgds
 

I think foundry guys want to prevent gates of your transistors from the voltage failure, due to accumulation of charge during the fabrication process. Am I right?
 

Is it a normal practice?, if I have an output terminal from the gate to control the voltage of the circuitry, is it advisable to insert this reversed biased pn junction?. Thanks in advance.

Rgds
 

I think that any circuit part connected to a pin needs to be ESD-protected

Gates-specifically- are more susceptible to failure on ESD events. Your foundry should supply you with documents on ESD-protection
 

Thanks for your replies,so reversed biased diode ESD protection is only used in the input-output pins, and hence it is not essential to place it on each of the gate of the transistors in the circuit, Is it true?. Pls shed some light on this issue.

Thanks in advance

Rgds
 

hrkhari said:
Thanks for your replies,so reversed biased diode ESD protection is only used in the input-output pins, and hence it is not essential to place it on each of the gate of the transistors in the circuit, Is it true?. Pls shed some light on this issue.

Thanks in advance

Rgds
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I think vladimir1984 is right. It is to prevent the antenna effect at the gate of the MOS device during the fabrication.So it is also called the antenna diode.
 

Have you added attena diodes before GDS out ?
 

I don't think it necessary to add a reverse-biased diode at EACH gate. But it is necessary to add diodes to SOME of gates which otherwise will voilate the antenna rule.
 

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