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electric - a VLSI design system
Contents
Compaction
The compactor attempts to reduce the size of a facet by removing unnecessary space between elements.
When invoked it will compact in the vertical and horizontal directions until it can find no way to
compact the facet any further. It does not do hierarchical compaction, does not guarantee optimal
compaction, nor can it handle non-manhattan geometry properly. The compactor will also spread out the
facet to guarantee no design-rule violations, if the "spread" option is set.
Description
Electric is a general purpose system for all electrical design. It currently knows about nMOS, CMOS,
Bipolar, artwork, schematics, printed-circuit boards, and many other technologies. It has a large set of
tools including multiple design-rule checkers (both incremental and hierarchical), an electrical rules
checker, over a dozen simulator interfaces, multiple generators (PLA and pad frame), multiple routers
(stitching, maze, river), network comparison, compaction, compensation, a VHDL compiler, and a silicon
compiler that places-and-routes standard cells.
In addition to the text terminal used to invoke the program, Electric uses a color display with a mouse
as a work station. Separate windows are used for text and graphics.
If a library disk file is mentioned on the command line, that file is read as the initial design for
editing. In addition, the following switches are recognized:
Design-Rule Checking
The incremental design-rule checker is normally on and watches all changes made to the circuit. It does
not correct but prints error messages when design rules are violated. Hierarchy is not handled, so the
contents of subfacets are not checked.
The hierarchical checker looks all the way down the circuit for all design-rules. Another option allows
an input deck to prepared for ECAD's Dracula design-rule checker.
Name
electric - a VLSI design system
Network Comparison
The network maintainer tool is able to compare the networks in the two facets being displayed on the
screen. Once compared, nodes in one facet can be equated with nodes in the other. If the two networks
are automorphic or otherwise difficult to distinguish, equivalence information can be specified prior to
comparison by selecting a component in the first facet then selecting a component in the second facet.
Options
-mdi
multiple document interface mode
-sdi
single document interface mode
-NOMINMEM
ignore minimum memory provided for JVM
-s<scriptname>
bean shell script to execute
-version
version information
-v
brief version information
-debug
debug mode. Extra information is available
-threads<numThreads>
recommended size of thread pool for Job execution.
-logging<filePath>
log server events in a binary file
-socket<socket>
socket port for client/server interaction
-batch
batch mode implies 'no GUI', and nothing more
-server
dump trace of snapshots
-client<machinename>
replay trace of snapshots
-help
this message
Pla Generation
There are two PLA generators, one specific to nMOS layout, and another specific to CMOS layout. The nMOS
PLA generator reads a single personality table and generates the array and all driving circuitry
including power and ground connections. The CMOS PLA generator reads two personality tables (AND and OR)
and also reads a library of PLA helper components (called "pla_mocmos") and generates the array.
Representation
Circuits are represented as networks that contain nodes and connecting arcs. The nodes are electrical
components such as transistors, logic gates, and contacts. The arcs are simply wires that connect the
nodes. In addition, each node has a set of ports which are the sites of arc connection. A technology,
then, is simply a set of primitive nodes and arcs that are the building blocks of circuits designed in
that environment.
Collections of nodes and arcs can also be aggregated into facets of cells which can be used higher in the
hierarchy to act as nodes. These user-defined nodes have ports that come from internal nodes whose ports
are exported. Facets are collected in libraries which contain a hierarchically consistent design.
Arcs have properties that help constrain the design. For example, an arc may rotate arbitrarily or be
fixed in their angle. Arcs can also be stretchable or rigid under modification of their connecting
nodes. These constraints propagate hierarchically from the bottom-up.
Routing
The router is able to do river routing, maze routing, and simple facet stitching (the explicit wiring of
implicitly connected nodes that abut). River routing runs a bus of wires between the two opposite sides
of a routing channel. The connections on each side must be in a line so that the bus runs between two
parallel sets of points. You must use the Unrouted arc from the Generic technology to indicate the ports
to be connected. The river router can also connect wires to the perpendicular sides of the routing
channel if one or more Unrouted wires cross these sides.
There are two stitching modes: auto stitching and mimic stitching. In auto stitching, all ports that
physically touch will be stitched. Mimic stitching watches arcs that are created by the user and adds
similar ones at other places in the facet.
See Also
Rubin, Steven M., "A General-Purpose Framework for CAD Algorithms", IEEECommunications, Special Issue on
Communications and VLSI, May 1991.
Rubin, Steven M., ComputerAidsforVLSIDesign, Addison-Wesley, Reading, Massachusetts, 1987.
Rubin, Steven M., "An Integrated Aid for Top-Down Electrical Design", Proceedings,VLSI'83 (Anceau and
Aas, eds.), North Holland, Amsterdam, 1983.
Mead, C. and Conway, L., IntroductiontoVLSISystems, Addison-Wesley, 1980.
Electrical User's Guide.
Electric Internals manual.
11/12/00 electric(1)
Simulation
There are many simulator interfaces: ESIM (the default simulator: switch-level for nMOS without timing),
RSIM (switch-level for MOS with timing), RNL (switch-level for MOS with timing and LISP front-end),
MOSSIM (switch-level for MOS with timing), COSMOS (switch-level for MOS with timing), VERILOG (Cadence
simulator), TEXSIM (a commercial simulator), SILOS (a commercial simulator), ABEL (PAL
generator/simulator for schematic), and SPICE (circuit level). MOSSIM, COSMOS, VERILOG, TEXSIM, SILOS,
and ABEL do not actually simulate: they only write an input deck of your circuit.
In preparation for most simulators, it is necessary to export those ports that you wish to manipulate or
examine. You must also export power and ground ports.
In preparation for SPICE simulation, you must export power and ground signals and. explicitly connect
them to source nodes. The source should then be parameterized to indicate the amount and whether it is
voltage or current. For example, to make a 5 volt supply, create a source node and set the SPICE card
to: "DC 5". Next, all input ports must be exported and connected to the positive side of sources. Next,
all values that are being plotted must be exported and have meter nodes placed on them. The node should
have the top and bottom ports connected appropriately.
Synopsis
electric [OPTIONS]
Technologies
A large set of technologies is provided in Electric. These can be modified with the technology editor,
or completely new technologies can be created. The following paragraphs describe some of the basic
technologies.
The nMOS technologies have arcs available in Metal, Polysilicon, and Diffusion. The primitive nodes
include normal contacts, buried contacts, transistors, and "pins" for making arc corners. Transistors
may be serpentine and the pure layer nodes may be polygonally described with the nodetrace command. The
"nmos" technology has the standard Mead&Conway design rules.
The CMOS technologies have arcs available in Metal, Polysilicon, and Diffusion. The Diffusion arcs may
be found in a P-well implant or in a P+ implant. Thus, there are two types of metal-to-diffusion
contacts, two types of diffusion pins, and two types of transistors: in P-well and in P+ implant. As
with nMOS, the transistors may be serpentine and the pure layer primitives may be polygonally defined.
The "cmos" technology has the standard design rules according to Griswold; the "mocmos" technology has
design rules for the MOSIS CMOS process (double metal); the "mocmossub" technology has design rules for
the MOSIS CMOS Submicron process (double poly and up to 6 metal); the "rcmos" technology has round
geometry for the MOSIS CMOS process.
The "schematic" technology provides basic symbols for doing schematic capture. It contains the logic
symbols: BUFFER, AND, OR, and XOR. Negating bubbles can be placed by negating a connecting arc. There
are also more complex components such as flip-flop, off-page-connector, black-box, meter, and power
source. Finally, there are the electrical components: transistor, resistor, diode, capacitor, and
inductor. Two arc types exist for normal wires and variable-width busses.
The "artwork" technology is a sketchpad environment for doing general-purpose graphics. Components can
be placed with arbitrary color and shape.
The "generic" technology exists for those miscellaneous purposes that do not fall into the domain of
other technologies. It has the universal arc and pin which can connect to ANY other object and are
therefore useful in mixed-technology designs. The invisible arc can be used for constraining two nodes
without making a connection. The unrouted arc can be used for electrical connections that are to be
routed later with real wires. The facet-center primitive, when placed in a facet, defines the cursor
origin on instances of that facet.
PNG Icons
SVG Icons
Emojis