Virtuoso XL Layout Editor User Guide
Generating Your Layout with Virtuoso XL Layout Editor
Shapes
A shape is a polygon or rectangle on a particular layer.
(shape (layer layer_name) (rectangle options))
(shape (layer layer_name) (polygon sequence_of_points))
A shape that is a floating rectangle or a floating polygon is called a floating shape.
Layers can also be defined externally, within the scope of the option using a shape for its own definition. A layer defined as part of the shape definition overwrites all external layer definitions.
Boundaries Section
The boundaries section defines the shape of the boundary. The syntax is
boundary_section(
[(boundary options)]
)
Boundaries Options |
|
The options are |
|
shape |
The shape outlining the boundary. By default, the shape is a |
|
rectangle with the aspect ratio defined byinitAspectRatio in |
|
the .cdsenv file. By default, or if the shape is floating, the lower |
|
left corner is placed at (0 0). |
layer layer_name |
The boundary layer name. The default is prBoundary. |
utilization N |
The area utilization factor. This factor is used to compute the |
|
boundary size for rectangular boundaries that do not fully define |
|
the size in the shape options. The value is ignored for polygonal |
|
boundaries and for rectangular boundaries whose shape options |
|
fully specify the dimensions. The default is the value of |
|
initUtilization in the .cdsenv file. |
Below is an example boundary definition:
boundary_section(
(boundary
(shape (layer prBoundary) (rectangle aspect_ratio 1.1))
December 2002 |
158 |
Product Version 5.0 |
Virtuoso XL Layout Editor User Guide
Generating Your Layout with Virtuoso XL Layout Editor
(utilization 0.25)
)
)
Below is a second boundary example:
boundary_section(
(boundary
(layer ("prBoundary" "boundary"))
(utilization 0.250000)
(shape (rectangle aspect_ratio 1.000000 lowerLeft (0.0 0.0)))
)
)
I/O Pins Section
The I/O pins section defines the shape and layer of the I/O pins for the new layout. The syntax is
I/O_section(
[global_pin_options]...
[(pin {pin_name | ( pin_name1 pin_name2 ... )} pin_options)]...
[changes to global pin options]
[more pins]...
)
Every pin entry has one or more pin names, corresponding to net names for which pins are defined. Pins have one or more options. Global options appear outside of apin entry and are overridden by corresponding pin-specific options. Changes to global options apply to subsequent pins (unless the pins each set a value for the corresponding option).
The global options in effect at the end of the I/O pins section apply to all pins not defined in the template.
Pin Options
The pin options and global pin options are identical, except that you cannot use expressions that evaluate to pin-specific values (such as pin width values based onminWidth) in the global options. The following options are available:
(multiplicity N) Number of pins for the given net(s). If N is greater than 1, all pins are identical. The default is 1.
December 2002 |
159 |
Product Version 5.0 |
Virtuoso XL Layout Editor User Guide
Generating Your Layout with Virtuoso XL Layout Editor
(layer layer_name) |
Layer for these pins. Every geometric pin must have a layer |
|
specification. This option can be used only with geometric pin |
|
types. |
(symbolic pin_name) |
Symbolic pin name. This option can be used only with |
|
symbolic pin types. |
(shape shape) |
The pin shape, a floating rectangle. The default shape is a |
|
floating rectangle with size equal to the minimum width for the |
|
pin layer. Size can be expressed using device rules, including |
|
the implicit ones, because the layer specification is always |
|
provided with pins. With symbolic pins, it is an error to specify |
|
anything but the width. |
(type pin_type) |
The pin type. Valid values are geometric or symbolic. The |
|
default is geometric. |
(position pos_spec) |
The pin position. By default, the pin is placed in the same |
|
relative position as in the schematic. Valid values for |
|
pos_spec are (left), (right), (top), (bottom), |
|
(edge num), (x x_value), (y y_value), (order |
|
num). |
|
You can specify the position as left, right, top, or bottom |
|
for a rectangular region, or as an edge number for any shape |
|
of region. The edge number num is the lower index of the |
|
edge’s two end points relative to the point ordering when the |
|
polygon was defined (in the case of rectangles, edge 0 is the |
|
left, edge 1 the top, edge 2 the right, and edge 3 the bottom). |
|
Position can, instead of or in addition to an edge position, be |
|
(x x_value) and/or (y y_value). If overspecified (for |
|
example, left as well as y), the absolute coordinate takes |
|
precedence. The order specification indicates the ordering |
|
along the appropriate edge (0 being left or bottom). |
Pin Definition Examples
Below are some pin definition examples:
(pin (net1) (layer metal1)
(shape (rectangle (minWidth)))
)
(pin "Vdd"
(layer metal1)
December 2002 |
160 |
Product Version 5.0 |
Virtuoso XL Layout Editor User Guide
Generating Your Layout with Virtuoso XL Layout Editor
(shape (rectangle width 3 height 3))
)
(pin "Gnd"
(layer metal2)
(shape (rectangle aspect_ratio 1.0 width 25))
)
I/O Section Examples
In this example, MET1 is the default layer for pins A, B, and C. MET2 is the default layer for D and E. All other pins, whether or not they are named in the template, will have MET2 (the most recent choice) as the default layer when you open the Layout Generation Options form.
(I/O_section (layer MET1) (pin A ...) (pin B ...) (pin C ...) (layer MET2) (pin D ...) (pin E ...)
)
In the next example, pins A, B, and C are on layer MET1. Their size is the minimum width of that layer. Pins Vdd and Gnd are on layer MET2. Their size is 10x10.
All the remaining pins in the cell (one for every net with an I/O terminal) are on POLY. Their size is the minimum width of POLY.
(I/O_section
(layer MET1) (minWidth)
(pin (A B C) )
(layer MET2)
(pin “Vdd” width 10 height 10 ) (pin “Gnd” width 10 height 10 ) (layer POLY)
)
Partitioning Section Examples
partitioning_section( sectionContents )
December 2002 |
161 |
Product Version 5.0 |