1) Corrected spurious error messages about cells already existing
in GDS when using "flatten" or "flatglob".
2) Fixed handling of resistance as a subcircuit parameter
3) Added area and perimeter resistance for a device; this is done
through the "devresist" statement in the tech file, which is an
extension of the original "fetresist" statement. Where "fetresist"
only supported type "linear", "devresist" supports types "area"
and "perimeter".
4) Support for CDL syntax, including generating subcircuit-like
parameters for components starting with SPICE-standard prefixes
like M, R, C, etc., adding "/" between pins and subcircuit name,
and saving the file as ".cdl" instead of ".spice".
5) Estimated L and W for devices whose geometry is complex and do not
reduce to a simple rectangle. L and W are estimated as the square
root of the area.
6) Changed the method of extracting L and W for diodes to use the same
method as capacitors. Note that diodes are not usually specified
by L and W, but if they are, this will produce the right result.
7) Corrected the reported filename and line number when printing error
messages related to errors inside a technology file, when the
technology file uses "include" to combine multiple files.
can provide a delta offset such as "l+0.06", indicating that
the extraction model has a length larger than the drawn device.
Previously the value was assumed to be in microns but did not
scale between the .ext file and the SPICE netlist. Corrected
so that it scales like the other parameter values, being
converted to internal units and tracking the internal grid
scale.
to be declared for each device model, so that different models can
be specified for different parameter ranges. For example, this
will simplify the definition of the high-sheet-rho poly resistors
and the bipolar transistors in sky130 by removing the need for ID
marker layers; it also allows the correct device model to be
extracted when reading data from GDS that does not contain the
extra (and not foundry-approved) ID markers.
'+' and '-' in the same way that '*' is currently used for specifying
a parameter scaling. The combination of a scale and offset for the
same parameter has not (yet) been implemented.
222 from Sean Cross. Corrected a few places where the blanket
conversion "Region"->"ExtRegion" picked up some comment lines
that were unrelated to the structure name.
This is diagnostic only and does not change the read-in
behavior.
(2) ext2spice: Corrected an error that had been introduced
into version 8.3.171 that accidentally marks all devices
as visited which causes all source/drain areas and
perimeters to be output as zero.
(3) extract: Sweeping changes to handling of fringe
capacitance. Removed the (recently added) "fringeshieldhalo"
parameter from the tech file. Reworked the fringe
capacitance models based on results from the "capiche"
project (github/RTimothyEdwards/capiche). Fringe shielding
is now done by clipping fringe at the boundary of a
shielding shape, rather than trying to calculate the
amount of shielding (as the "capiche" project proved this
to be equivalent). Values for partial fringing are modeled
by atan(x), which like the sidewall (1/x) curve, extends to
infinity and values are limited by the halo but do not
otherwise depend on the halo. Because of this, the halo can
be made variable and controlled by the user for deciding on
the tradeoff between accuracy and run time. A new command
option "extract halo" was added to allow this control over
the halo distance.
This commit makes the code (mostly) C99-compatible, enabling to compile
it without the -Wno-error=implicit-function-declaration flag. This
way, Magic becomes usable on arm64 architectures, specifically on Apple
computers with M1/M2 SoC.
reading GDS files, caused by an unneeded change to pass both
the "original" filename and the actual filename when handling
compressed files---The original filename is unneeded.
(2) Implemented several new methods for parasitic extraction. The
first is an option offset value to apply to sidewall calculations.
This handles issues where actual wire separation is different
from drawn wire separation, which can be significant for the
1/d calculation of sidewall coupling. The second method is to
use the recently-added fringe halo to compute the coupling of the
fringe capacitance to nearby wires. Prior to this change, all
fringe capacitance was applied to surfaces directly under a wire
edge as if the fringe capacitance did not extend outward from the
edge. Now the capacitance is properly pro-rated for the position
of any overlapped shape inside the fringing field. Finally, the
third method added is a new search algorithm for finding the
nearest shapes along the length of a boundary. This is used for
sidewall coupling and fringe shielding, where the nearest shape
dominates the coupling, and any shapes behind are shielded and
may (to first order) be ignored. Previously, the entire halo
was searched without regard to shapes shielding other shapes
behind, and a recent correction added an ad-hoc search for
blocking shapes that was inefficient and not always correct.
The new method is both efficient and accurate.
is specified in the extraction section of the techfile, then magic
will compute the effect of a nearby shape partially shielding the
sidewall overlap capacitance, which approaches 100% shielding as
the shapes converge to zero separation. This method prevents
magic from vastly overestimating the fringe capacitance of closely
spaced wires, which was magic's worst problem with parasitic
accuracy. The "fringeshieldhalo" value is the distance at which
the fringe shielding becomes negligible. Typically, it will be
about three times the distance at which half the fringe value is
shielded. It may be necessary at some point to make both the
fringe shielding halo and the sidewall halo values per-type values
(or per-plane, at least). For now, it should suffice to bring
Magic's parasitic extraction back in line with other tools.
not be seen during hierarchical processing, causing the substrate
to get split into several names that may conflict in the netlist.
At issue is the fact that ExtLabelRegions() will not attach a
default substrate label to a default substrate region. This may
need further untangling, as extFindNodes() will set the default
substrate node and is sometimes followed by ExtLabelRegions(),
which will label it. Any place ExtFindRegions() is called, this
could be an issue.
a routine that should have been called with a NULL argument, but
instead was called with no argument, making the behavior system-
dependent. Revised the parsing of the "defaultareacap" and
"defaultperimeter" statements in the tech file, such that the short
version of both statements gets automatic handling of the substrate
and isolated substrate areas; this goes back to the recent change
in extraction behavior to redefine the "substrate type" (e.g., pwell)
during extraction as defining isolated substrate areas, and not the
default substrate. The earlier code change dealt with problems
related to extracting nodes and regions, but did not consider how
parasitic capacitance was affected. This commit resolves that issue.
time ago by cleaning up excess usage of "equiv" lines in the .ext
file output. The hierarchical extraction code did not distinguish
between node names which were output and those that were not,
requiring a setting "extract do aliases" to force all node aliases
to be output with "equiv" statements. So hierarchical names
might be any alias, whether output or not, and "merge" and "cap"
lines might contain references to nodes that were not output,
causing them to be disconnected nodes. This fix handles the
"extract no aliases" (default) case by flagging node names that
are redundant and not output, and not creating hierarchical names
with them.
optimization done in ExtFlat, which is to keep a count of the
number of different node names assigned to the node so that when
merging, the one with fewer nodes can be updated to match the one
with more nodes. Note: This change is made on the assumption
that the names for node1 and node2 are equally preferred.
Supposedly the first name in the node list is canonical, so if
node1 is preferred in any case, it may be necessary to move
the first item of the second list to the beginning (a minor code
change).
restricted to its original intent, which is to replace the long name
formed from the plane short name and the "minfinity" coordinate.
This avoids issues with conflicting substrate names derived from a
real layer such as pwell. Also, the global substrate node name now
returns the variable name without the "$" in front if the variable
has not been set to anything. This avoids potential syntax errors
in the netlist.
include (1) specification of sidewall or surface to use for
each type individually, rather than a single method for all
types, and (2) specification of a linear model R = Ax + B for
the ratio limit when diodes are attached to the wire, where x
is the diode surface area (unitless, as this is a ratio).
checks. Added new command "antennacheck" and a routine that
adds feedback entries where violations are found. Extended the
syntax of the extraction section of the techfile to support the
antenna ratios and antenna calculation methods.
principle layer name, which should not happen (especially in the
case of space, where layers may be aliased to "space" to make them
ignored on input). Also: Implemented a "-<types>" option to the
"substrate" record in the techfile to declare types which shield
layers from the substrate. This allows types like pwell to be used
in different contexts, e.g., as part of the substrate, or as a P-well
in deep N-well, without requiring a different type. This works in
conjunction with the recently-implemented "+<types>" ID types for
devices. All of this may seem unnecessary but helps to reduce the
number of layers needing to be defined, and the subsequent complexity
of the DRC rulesets.
to be more robust and not depend on the ordering of the devices in
the techfile. The extraction method now keeps a mask of which
properties of the device (source/drain types, substrate type,
identifier type) have been found, and will look only for device
records that match what is known about the device. Added a device
identifier record which is the last record before parameters if the
record begins with "+". This allows marker layers to be placed
over a device such that it will extract with a different type.
This helps reduce the complexity of the techfile and allows
certain specialized devices like RF or ESD to be identified without
a separate layer type for the device.
R. Timothy Edwards
Darryl L. Miles
Sean Cross
Alessandro De Laurenzis