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The Quick Paths Button: Show Electrical Connectivity

This command is functionally similar to the Show Paths command, but operates outside of the extraction system. For complex designs, the initial extraction setup can be quite time consuming. Using this command will avoid this delay. Of course, if extraction is needed for other purposes, the Show Paths should can be used, as it is a bit quicker (once extraction is set up) and has a more powerful path determination algorithm.

The Quick Paths algorithm, unlike Show Paths, will ignore layers that are set invisible.

Since extraction is not used, there is no concept of devices, so that results may not be as expected, and not be as seen with the Show Paths command. For example, consider MOS devices. Since, the source and drain are connected to a common area of the ``active'' layer, which is a Conductor, the simple algorithm used in this command will interpret the source and drain as being connected (since it does not recognize the MOS device). In order to get meaningful results, it may be necessary in this case to temporarily remove the Conductor keyword from the active layer. This can be accomplished with the Extraction Parameter Editor.

If layer-specific selection is enabled, one must click on an object on the current layer to select the path. Otherwise, clicking on any conducting object will highlight the connected objects. Only one path is shown.

The boolean variable LayerSearchUp, if set, will enable searching for layers from bottom to top if set, rather than the default top to bottom. This affects the conductor chosen if the user clicks over more than one conductor layer, and layer-specific mode is not active.

If a dark-field ground plane has been specified in the technology file, the implied connectivity to ground is similar to that in force for the extraction system, though can be specified with the QpathGroundPlane variable. This can be set with the !set command to an integer in the range 0-2.

0 This is the default. If an inverted ground plane has already been created and is current, it will be used when determining paths. If the ground plane does not have a current inversion, the absence of the layer will imply a ground contact, as in extraction without the MultiNet keyword. This choice avoids the sometimes lengthly inversion computation, but makes use of the inversion if it has already been done.

1 If the extraction system would use an inverted ground plane, it will be created if not already present and current. The path selection will include the inverted layer.

2 The Quick Paths command will never use the inverted ground plane.


next up previous contents index
Next: The Show Paths Button: Up: The Extract Menu: Extraction Previous: The Select Groups Button:   Contents   Index
Stephen R. Whiteley 2006-10-23