HINTS & TIPS


Q: I run DRC, find one-two violations, correct them, then I re-run DRC to check whether my corrections worked. However re-running on the whole design is time-consuming. How can I run DRC over a piece of the layout, in the vicinity of the introduced changes?

A: Recent release of Expert contain two important features that avoid multiple batch DRC reruns for the whole design.

  • "DRC in Area" command allows you to run DRC script to be run it the selected rectangular area of the layout.
  • "DRC Guard" allows monitoring of design rule violations on the fly while editing the design.

Please read the release notes for Expert v. 156 for details. (All release notes are accumulated in the file relnotes.txt).

Q1: When I plot my design on a laser printer some
regions are not plotted at all.

Q2. Stipple patterns on screen and on plot
look differently.

A: In both cases the reasons are the same. Unfortunately, color capabilities of screen and plotting devices often do not match. In particular, some nonsaturated colors clearly visible on the screen are mapped into white color on the plot.

One more problem arises if you try to plot a layout drawn in stipple mode of filling. When preparing data for plotting the software tries to match RGB values of colors from layout to the available set of plotter colors. To do so, plotters use dot patterns of primary colors. These dot patterns may be either regular or diffuse ones. Stipple mode of filling also uses bit patterns for filling. When plotter's color dot patterns and stipple patterns interact, the results can be totally unpredictable. Therefore color matching has chance to work correctly for solid-filled and wireframe shapes only.

Expert provides two means to alleviate these problems:

- plotting style setup, see Figure 1;

- color libraries.

Plotting style setup, among other possibilities, allows you to assign filling modes and colors for layers different from the ones used on screen. In particular, in troublesome situations is is possible to replace stipple filling by hatching. Hatching is filling by "wireframe" lines rather than by dot patterns, therefore it does not interfere with color matching tricks. However this advantage is linked with a drawback: there are six possible types of hatching, see Figure 1.

 

Figure 1. Style Setup.

 

 

Color libraries allow you to define "named" colors. This allows you to predefine a set of "good" colors for further use in setups, see Figure 2.

Moreover, color libraries for plotter and for screen may contain colors with the same name, but with different numeric RGB values, so that the named color on screen will look exactly the same as the color with the same name for printer/plotter. Such separate color definitions may be prepared for all types of plotters you have.

Of course, such kind of color/style setup requires some tedious tuning, including trial printouts. But please remember, color library tuning must be performed only once.

Figure 2. Color Setup.

 

Q: Expert's tool bars occupy too much screen space.
I would like to have more space for layout.

A. In Expert the whole screen may be used for editing in the following way:

using menu Setup>>Customize assign shortcuts to most frequently used commands and/or add them into the custom menu (the one appearing if you depress right mouse button inside design area).

  • remove all unnecessary toolbars;
  • assign shortcuts to show/hide necessary toolbars; (suppose you assign key "L" to the Layer bar)
  • holding the CTRL key, drag the necessary toolbars so that will not dock to the boundary of Expert's window.
  • then if you press "L" several times, you will see that the layer bar shows and hides, while the layout occupies the whole screen.

Q: How can I report long parallel interconnect
segments that run too close to each other?

A: An example check is as follows:

OutDistance:

layer1=m1, layer2=m2, type=LT, value=0.25um, options=(S1,P,O,L=GE 6um,L1=GE 5um,L2=GE 4um);

Actually, it was generated through the user interface of the DRC script panel. Click "Check" at DRC panel, then select a basic operation, then click "Options" button.

 

The following options were selected at the "Options" panel:

  • parallel
  • with projections
  • length of segments
  • length of errors 1
  • length of errors 2
  • report error subsegments.

 

Users should try different combinations of these options (and their opposites) and choose what kind of check is required.

A more advanced check, similar to the PLENGTH command, is under development.