( ESNUG 429 Item 5 ) --------------------------------------------- [06/03/04]
From: Gal Gottlieb <galg=user domain=dsp.co.il>
Subject: It Seems Odd That AstroRail Uses Power Sources At Multiple Levels
Hi John
I am checking the AstroRail of Synopsys. I am building a flow. I have some
lack of knowledge regarding the CSF file (Current Source File). My design's
power consumption is calculated as the power consumed at the transistors
level. We neglect power consumption on the routing network. As I
understand it, when AstroRail generates the CSF file (not a Transistor Level
extraction), AstroRail specifies current sources -- meaning locations of
power consumption. By locating intersections of different metal layers it
locates points where current is drawn. In the file AstroRail generates one
can modify the values of the drawn current entry field and actually set
different power consumption distribution (set weights).
The AstroRail form that generates the CSF file has several check boxes in
the "Intersections Types" area : polycont, M1-2, M2-3, M3-4, M4-5... This
tells it where to create current sources. AstroRail allows me to select
several Intersection Types at one time. I don't understand this. It should
allow only one check box because if there are several Intersection Types
there are current sources at different layers? The assumption that the
transistor-level power having current sources at more than one layer seems
excessive (too much). One layer current source should be sufficient.
What do you know about this? Where can I get detailed info of the way the
algorithm of the "rail analysis" of hard macros work? How does AstroRail
use the supplied current source file?
- Gal Gottlieb
DSP Group, Inc. Hertzelia, Israel
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