There are many kinds of PCB design software, the market is currently used mainly include: Cadence Allegro, Mentor EE, Mentor Pads, Altium Designer, Protel, etc., in which the highest market share of Cadence Allegro.
1, mainstream PCB design software features:
(1) functional integration: a complete design platform, with schematic design, PCB design, circuit simulation analysis and other functions;
(2) functional components: different functions are implemented in different software module components, users can choose to purchase and install;
(3) circuit analysis is powerful: to meet the current trend of rapid development of PCB, to determine the design rules in order to design rules driven PCB design and implementation;
(4) support team work: PCB can be divided into modules, online or offline mode collaborative design
PCB design software using the same method, based on the basic PCB design process, the convergence of the functional modules, but the specific software menu or design sequence of operations are different.
2, the principle of high-speed PCB design
First of all, what is "high speed"?
Generally speaking, the traditional circuit theory is applied to the circuit structure analysis of the signal interconnection whose circuit size is much smaller than that of the highest frequency in the transmission signal. At this time, the signal is equivalent to a first-order circuit interconnection element, known as the "lumped element" (Lumped Elements); on the contrary, when the size of the signal interconnection circuit corresponding to the highest frequency close to the designer more concerned about the transmission signal in wavelength, due to the size and phase of interconnect paths on different positions of the voltage or current of all may be different, the signal interconnection is equivalent to multi order circuit components, so it is called the "distributed element" (Distributed Elements).
The above is the "signal integrity theory for signal transmission behavior of PCB interconnection line understanding, signal edge rate almost completely determines the maximum frequency components in the signal, usually when the interconnect transmission delay signal edge time is less than 4~6 times under the condition that the signal interconnection path would be regarded as a distributed parameter model, need to consider the" signal integrity "behavior.
The so-called "high speed" means "interconnection delay" signal edge time is less than 4~6 times, we can see that the signal circuit board transmission is "high speed", not only the edge rate depends on the signal path length, but also depends on the size of printed circuit board, when there is a certain proportional relationship between them, the signal should be in accordance with the "high speed signal processing.
The principle of high-speed PCB design comes from the theory of signal integrity, students can refer to the study and teaching materials and literature. High speed PCB design has been fully supported by the PCB design software tools, the simulation and design of PCB design rules, implementation, are implemented in the PCB design tools.
3, PCB design need to master knowledge
3.1 knowledge of needs
Circuit principle, signal integrity, power integrity, structure, power supply, thermal design, electromagnetic compatibility, machinability, testability, etc.
3.2 basic knowledge
(1) installation and operation of design software
(2) basic knowledge of printed circuit board manufacturing (machining process, machining materials, etc.)
(3) the basic use of hardware schematic tools (with PCB design related functional modules)