what are types of I/O off-chip pins?

[mohazaga]

Hi ,,,

When designing IC , it's suggested to use specific off-chip pin type for each of I/O signal port. Vdda for power, Vssa for ground, Vin for in signal, and Vout for out signal. they also recommend to used Vddo. it's not connected to any port internal the chip. The Vddo pin is connected to all other I/O off-chip pins by ring of metal-3 in the chip layout.
What is the function of Vddo? why it's connected to all I/O off-chip pins? to which its connected externally?

Regards

 

[sowmya005]

Hi Mohazaga,
Pl go through the documents u got along with the IO library.
Load the lef and study the layout the IO cells.

 

[leo_o2]

It should be decided by the specific IC. It is not required by all IC. I guess it might be used for shielding in your IC.