1
1
<!-- HEADER 9-7-1: Introduction -->
4
Electric can compare two different cells and determine whether their
5
networks have the same topology. This operation is sometimes called
6
Layout vs. Schematic (LVS), but because Electric can compare any two
7
circuits (including two layouts or two schematics) we use the term Network
8
Consistency Checking (NCC).
3
Electric can compare two different cells and determine whether their networks have the same topology.
4
This operation is sometimes called Layout vs. Schematic (LVS),
5
but because Electric can compare any two circuits (including two layouts or two schematics)
6
we use the term Network Consistency Checking (NCC).
10
The Java Electric NCC differs from the C Electric NCC in two
8
The Electric Network Consistency Checker has two algorithms for matching networks:
14
The Java Electric NCC firsts attempts to discover circuit mismatches
15
using a new algorithm called "Local Partitioning". We do this
16
because Local Partitioning provides much more precise and
17
intelligible mismatch diagnostics. We fall back upon the <A
18
HREF="http://www.cs.washington.edu/research/projects/lis/www/gemini/gemini.html">
19
Gemini algorithm</A> (Ebeling, Carl, "GeminiII: A Second Generation
20
Layout Validation Program", <I>Proceedings of ICCAD</I> 1988,
21
p322-325.) only as a last resort. In practice upwards of 95% of all
22
errors are found by Local Partitioning.
25
The Java Electric NCC has a "hierarchical" mode. When comparing a
26
cell hierarchically, NCC first tries to compare the cell's
27
descendants. We <i>strongly</i> recommend this mode to the user
28
because it allows the Local Partitioning algorithm to provide even
29
more precise and intelligible mismatch diagnostics.
10
<LI>NCC firsts attempts to discover circuit mismatches using an algorithm called "Local Partitioning".
11
Local Partitioning provides precise and intelligible mismatch diagnostics.</li>
12
<li>After Local Partitioning, NCC uses the
13
<A HREF="http://www.cs.washington.edu/research/projects/lis/www/gemini/gemini.html">Gemini algorithm</A>
14
(Ebeling, Carl, "GeminiII: A Second Generation Layout Validation Program", <I>Proceedings of ICCAD</I> 1988,
16
In practice upwards of 95% of all errors are found by Local Partitioning.</li>
32
The Java Electric NCC is also significantly faster than the C Electric
33
NCC. For example, for one of our chips, C-NCC flat took 48 minutes,
34
Java-NCC flat took 3.5 minutes, and Java-NCC hierarchical took 9
38
<H4>New body connection checking (Version 8.09b onwards)</H4>
39
This version of NCC can now optionally check that transistor bodies
40
are properly connected. See the description of the NCC preferences
19
NCC has a "hierarchical" mode which starts at the bottom of the hierarchy in the leaf cells
21
This mode is recommended because it allows the Local Partitioning algorithm to provide even
22
more precise and intelligible mismatch diagnostics.