Cadence Design Getting Started FAQ Analysis

writer: G March 23, 2018

1. How does Cadence optimize cabling without changing the overall shape of the cabling?

After the wiring is completed, it needs to be optimized. Generally, the system automatically optimizes, mainly changing the right angle to 45 degrees, and the smoothness of the lines. Route->gloss->parameters. In the list that appears, select Line smoothing. Gloss can be done. However, in order to ensure that the trace distances are equal in the route, some routes are deliberately bent into some curved lines. When optimizing, click Line Smoothing on the left. For the box, just select convert 90's to 45's and remove all the other hooks. This will not straighten or warp the designer's deliberately bent traces.

2. Cadence do package library to pay attention to?

You can do encapsulation either in File->New->package symbol in Allegro or using the Wizard function. In this process, the most critical point is to determine the distance between the pad and the pad (including the adjacent and corresponding pads), so as to ensure that the pin of the component can be completely affixed to the pad without any deviation in the later packaging process. If you only know the size of the Pin, you should design the size of the pad slightly larger than Pin, the general width is 1.2 ~ 1.5 times, length is about 0.45mm. In addition to the size of the pad needs special attention, but also add some layers, such as SilkScreen_top and Bottom, because in the future when you need to do the painting file (gold finger can not), Ref Des is also best labeled on the Silkscreen layer, and pay attention to silk screen Layers do not draw on the Pad. It should also mark the location of pin 1 and there are some special packages, such as gold finger, plus a layer of Via keep out, or route keep out, etc. These can be added according to your requirements. The operation must pay attention to is to build the package, must not forget to click on the Create symbol, otherwise there is no *.psm file generated, it can not be called in Allegro.

3. How to define your own shortcut keys in Cadence Allegro?

In the blank box below allegro, immediately followed by the command> prompt, enter the alias F4 (shortcut) room out (command). Or there is an env file in the Cadence installation directory /share/pcb/text. Open it with WordPad, find the Alias-defined part, and manually modify it.

4. After the completion of Cadence routing, if you need to change the package library how to deal with?

After the device is placed, if there is a change in the package library, you can use Place->update symbols. If there is a change in the pad, be sure to tick the update symbol padstacks. After the wiring is completed, try to avoid changes to the package library, because if the update, the connection to the pin will move with the Symbol, resulting in the loss of many connections, the specific solution remains to be studied.

5. How does Cadence create its own component library?

After creating a new project, the first step in drawing the schematic is to first create the library you need. The tool used is the part developer. First, create a directory that stores the component libraries (such as mylib), and then use the WordPad. Open cds.lib and define: definition mylib d:\board\mylib (the path where the directory is located). This creates your own library. In the Concept_HDL component->add, click search stack, you can join the library.

6. How does Cadence get a library of all the components after the layout?

If all kinds of files in the physical directory are too cumbersome and want to delete some useless files, or if there is only one *.brd file and want to get all the information of the components and the pad package library, you can use this method: save the *.brd In a new directory, select all options in File->Select export->libraries, and then export to generate all *.pad,*.psm,*.dra files in your new directory.