I/O pad simulation : calculation of drive current ,pull-up and pull-down resistances

[dileep4111]

What is drive current for a PAD and how to decide drive current for I/O PAD while doing characterization.Also how to calculate the pull-up and pull-down resistance for I/O pad cells.

Thanks

 

[erikl]

What is drive current for a PAD

The current which can be driven by the output buffer of the pad.

how to decide drive current for I/O PAD while doing characterization.

While doing characterization you measure - you can't decide on your results (just if they are reasonable).

how to calculate the pull-up and pull-down resistance for I/O pad cells.

Depends on requirements (customer's or yours).

 

[dileep4111]

How should i characterize the drive current of pad. Currently i am using Spectre tool from cadance.
thank you

 

[erikl]

Which type of pad? Analog or digital? Output only or I/O pad?

 

[dileep4111]

It is I/O PAD

 

[erikl]

It is I/O PAD

Again: Analog or digital? Provide its schematic!

BTW: Slowly I'm running out of endurance, if you're not even willing to provide the info necessary to be able to respond to your questions!

 

[dileep4111]

It is a bidirectional Digital PAD from TSMC

 

[erikl]

So why don't you simply have a look into the respective TSMC Standard I/O Lib Data Book? E.g. this one:
If you rightfully got the schematic and/or layout of the cell, you'd have access to it, too. There you can find the drive capabilities:
Pls. notice the correlation between a part of the cell name and its drive capability!


If you want to simulate: Enable the output, set a logic input voltage, measure the output current, either in short circuit mode, or into a known output load up to your requirement. Repeat this for the other logic input voltage.

Hope this helps!