Allegro PCB Design Tutorial
This tutorial is intended for beginners in printed circuit board design who wish to complete a board using Cadence Allegro Tool. This tutorial is for Windows XP but most of the things should be easy to be extended for Linux or Unix.
Those who had experience with one or more PCB design tool may skip this page. Others may like to get a general view of the design process which is follows:
1. Select the components (capacitors, sockets, etc.) you will be using on your board. Once you have a list, collect the datasheets and look at the suggested footprints (that is, the hole sizes or pads) in those documents.
In actual practice following are the main categories of the components used
Resistors, Capacitors,Inductors, Ferrite Beads
Diodes, Transistors, FETS, LEDs
ICs, BGA ICs
Interestingly, you will be devoting most careful about the electrically simplest component - connectors. You must get the physical part in hand to verify pin number 1 orientation and dimensions.
2. For each component, you have to create a footprint. Footprint is a physical view of the component that includes the holes through your board or pads for surface mount components. Footprints can be reused in the same board several times.
In practise, you will already have most of the footprint available and you should need to create only few additional footprints for a new design. You will need to be careful to verify that the existing footprint in your design library matches the mechanical dimension of the component according to its datasheet.
There are reference designs available from companies like freescale. You may get their allegro design and export the footprints that you can use after minimal or no change.
3. You have to create a schematic view of your board. This means adding different components on your board and connecting them with wires. We will be creating Schematics using Orcad. If you are not familiar with Orcad you may want to take an Orcad tutorial.
4. Once you have the schematic, you have to generate the netlist and import it to Allegro PCB Editor to complete the board layout. You place the components, define power and ground planes, route physical wires using this tool. Finally you must verify the board for errors.
5. After you have the board layout, you generate a few files called artwork or gerber. The gerber files are used by PCB Manufacturer to manufacture the board.
Note: Most designs today are use high speed signals. You may like to get the book - Signal Integrity for PCB Designers from Amazon for $55 or for $40 here .