On Jan 3, 2011, at 3:33 AM, Stephan Boettcher wrote:
John Griessen j...@ecosensory.com writes:
On 01/02/2011 04:14 PM, Stephan Boettcher wrote:
If you do not use it, why do you care about associating
netnames to traces?
That's not about auto DRC enforce drawing, it's about searching
for parts related to schematic and cross probing
and creating layout dereived models of trace capacitance
for simulations.
All of this should depend on the actual copper connectivity, not on some
(invisible) attributes of drawing elements.
Yes. the netname belongs to a different level of abstraction, where geometry is
assumed not to matter. Only topology matters. And while one can talk about the
capacitance between nets, one generally cannot deal with inductance and
resistance in this manner.
I am increasingly seeing fast digital chips that are designed to be connected
by transmission lines, not nets. Right now, every layout person I know pretends
that transmission lines are composed of nets, and then manually forces their
tool to create a transmission line geometry.
As this gets more common, I expect that it will be important that the tools be
capable of more automation in this area. gschem is in good shape here, as it
does not make any semantic assumptions about its nets, at least if you turn
off net consolidation. nets in gschem therefore can easily represent
transmission lines (or busses, as Paul Tan has shown). gnetlist isn't so
flexible, as it hides the geometry, revealing only topology, and also hides
attributes attached to nets.
---
John Doty Noqsi Aerospace, Ltd.
This message contains technical discussion involving difficult issues. No
personal disrespect or malice is intended. If you perceive such, your
perception is simply wrong. I'm a busy person, and in my business go along to
get along causes mission failures and sometimes kills people, so I tend to be
a bit blunt.
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