QRC parasitic extraction when there is a separate digital/analog grounds

Status
Not open for further replies.
S

sam2011

Newbie level 6
Joined
Nov 9, 2010
Messages
13
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Activity points
1,350
Hi,

I'm designing an ADC with 2 separated grounds: AGND and DGND - one for analog and other for digital domain. I'm using the QRC to perform a parasitic extraction of my final layout. In the QRC's "Extraction" tab, there is a "Ref Node" field. In this case, is necessary to fill "Ref Node" field with AGND, DGND or short both in layout and rename the net?
 

I usually short them. That said - I have a one extra hierarchy level for LVS where I short the Analog and Digital grounds together (as if on PCB) and during QRC my reference s the external ground connection.
That said - I do not think it makes much sense to run QRC on digital. With propper library you should not have to.
 
Completely Agree with Teddy.

After placing them in a new layout and shorting them for extraction AGND and DGND will be GND, but when you will see the report of QRC ( which comes from layout ) if a analog net has 25pF with GND means net is coupled with AGND same with Digital nets .

It only difference of names nothing else.
 
Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…