Please see our document on using the CDK Virtuoso customizations.
FAQs:
I'm used to Magic. What are all these layers in the layout window?
We've made a brief description of the mask layers used. Also, using pcells can reduce the need to be intimately familiar with your technology.
What's the difference between nactive, pactive, cactive, tactive and plain old active?
nactive, pactive, cactive, and active are translated to the same CIF/GDSII layer. nactive, pactive and active can be used interchangeably, but it's easier to distinguish NFETs from PFETs on-screen if you draw them using nactive and pactive respectively.
cactive is used only to draw the collector region of NPN transistors in processes that support this option.
Note since all four are exported as active, if you import a CIF/GDSII file all four layers will also be imported as active. If you then want to convert them back, you can use the approriate extraction switch.
tactive denotes thick-oxide (i.e., high-voltage) devices, in processes that support this option, and is a different mask layer than the others.
How do I highlight an entire node?
Just click on it in the extracted view. (Clicking on a shape in the
layout view will select just that shape, since the layout view doesn't
contain connectivity information.) To deselect, click on an empty area.
(If you find that this is interfering with any probing, you can set the
variable NCSU_DontUseProbeHighlighting = t to use the old
highlighting method.)
What's a good way to draw interconnect wires?
Use the path tool (select the ``Create->Path...'' menu entry). There's a facility to allow automatic placement of vias (path stitching), such as for going between metal 1 and metal 2.
Are any other layout macros available?
Each of the technology libraries (e.g. NCSU_TechLib_tsmc03) contains several ``parameterized cells'' (pcells). Pcells include MOS devices, all types of contacts and vias, and a thin-ox capacitor (where applicable). If you're going to do any layout, you should definitely read a little more about them.
Hit l or use the ``Create->Label...'' menu entry. Note that the label associates with the physically highest shape underneath the hotspot. E.g., if you create a label on an overlap of metal 1, metal 2, and poly, the label will associate with the metal 2. The CDK label-creation routine understands bus notation similar to that in Composer; e.g., use bus<7:0> to label an 8-bit bus, or bus<7:0:2> to label every other bit. Generally, these labels should be on the ``text'' drawing layer.
Another method, especially useful if the shape you want to label is underneath other layers and inaccessible, is to select the ``Create->Pin...'' menu entry. Use symbolic pins (which are located in the sym_pins category in either your design library or it's attached technology library) to label shapes that are obscured by shapes on other layers. Symbolic pins are not written out when you make a CIF or GDSII file.
The values you see in the properties dialog come from a simple heuristic: the source/drain rectangles are 2.5 times ``minLength'' on the top and bottom and ``width'' on the left and right. These are mainly useful for doing simulations from schematics. When you netlist your extracted view you should see the correct (i.e., measured) values.
How do I put a picture on my chip?
Use P2M, which you can access through the ``NCSU->Import JPEG picture...'' menu entry in Virtuoso. It reads in a JPEG image and inserts it into your layout. If you need to import a different type of image format, get the standalone version of p2m.
I need to put labels on my chip for microprobing. Is there an easy way to do that?
Use the ``NCSU->Import text...'' menu entry in Virtuoso. It lets you import a text string in any available X Window font.
The CDK includes MOSIS wirebond pads for some technologies. Check the appropriate CDK technology library for a wirebondPads category.
See the document on creating CIF or GDSII mask data with the CDK.
The NCSU CDK is © NC State University, 1998-2000. Users are free to use or modify the NCSU CDK as appropriate as long as this notice appears in it. You are also advised that you use the NCSU CDK at your own risk. By using the NCSU CDK, you assume all liability for any resulting errors and problems.