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Message started by taos on Aug 6^th, 2006, 11:43pm

Title: The flow of the PDK design?
Post by taos on Aug 6^th, 2006, 11:43pm

Who can describe the detailed flow of the PDK design? Thanks a lot!

Title: Re: The flow of the PDK design?
Post by jbdavid on Aug 29^th, 2006, 10:26am

Are you looking for a PDK developement Guide?
a PDK Installation Guide?
or PDK Users Guide?
Jbd

Title: Re: The flow of the PDK design?
Post by taos on Aug 30^th, 2006, 2:06am

PCell Design.
The Pcell Layout cannot change when the CDF parameters change.
How to attach them?
Thanks!

Title: Re: The flow of the PDK design?
Post by jbdavid on Aug 30^th, 2006, 11:35pm

There are some special things done in the pcell code to get CDF parameters..
and of course just cause they change in the schematic doesn't automatically mean they change in the layout..
you need to update the device from the schematic (in a VXL flow)

I don't know the right answer, but your title isn't likely to attract the folks who can answer this question..
hint Pcell design procedure is just one step in the PDK design flow..

Jonathan

Title: Re: The flow of the PDK design?
Post by Andrew Beckett on Sep 12^th, 2006, 1:40pm

Provided that you ensure that the default value of a CDF parameter matches the default value of the pcell parameter, you don't have to do anything special in the pcell.

When you change the value on the create instance or edit properties form, of a property governed by CDF, then the property is stored as an instance property on the instance. If this is an instance of a pcell, then those properties which are pcell parameters govern the lookup of a pcell submaster (i.e. variant) with that particular combination of parameter values. If one is not already available in memory, the pcell code will be evaluated with that set of parameter values, and the submaster will be created.

It is possible to write your pcell to explicitly look up the values from the CDF - normally only for finding default values - but it's rarely necessary. Note that pcells can only be communicated with via instance parameters - these are the only things that trigger re-mastering.

Regards,

Andrew.