【 Weak current College 】 integrated system PCB design of new technology 】

The current electronic design are largely integrated system-level design, the entire project contains both design and hardware of software development. Such technology characteristics to engineer a new challenge. First of all, how early in the design of the system software and hardware much more reasonable function partition to form a valid function structure framework, to avoid redundant cyclic process; second, how in a short time to design a high performance, high-reliability PCB Board. Because software development is largely dependent on the hardware implementation, only make the whole machine design once adopted, will be more effective to shorten the design cycle. This article discusses new technology background, system-level design of the new features and new policies.

As is known, the rapid development of electronic technology, and the root cause of this change, the main factor from chip technology progress. Semiconductor technology is becoming more and more physical limit, has now reached deep sub-micron level, VLSI circuits become mainstream chip development. While this technology and scale changes and poses many new email design bottlenecks throughout the electronics industry. Board-level design has also been a very great impact, the most obvious change is the type of chip packaging of great wealth, such as BGA, TQFP, PLCC, package type emerge; Secondly, high-density pin package and small packaging has become a fashion, with a view to achieving the total product miniaturization, such as: MCM technology is widely used. In addition, chip, the improvement of working frequency, so that the system operating frequency increases.

While these changes inevitably to Board-level design brought many issues and challenges. First of all, due to the high density pin and PIN size increasing physical limit, resulting in a low rate of butung; Secondly, because the system clock frequency increases, causing the timing and signal integrity issues; third, engineers hope to PC platform with better tools to complete complex high-performance design. Thus, we can see clearly that the PCB design is one of three trends:

· High-speed digital circuit (that is, a high clock frequency and fast edge) is designed to become mainstream.

· Product miniaturization and high performance must face in the same block Board due to mixed signal design technology (digital, analog and RF hybrid design) effect of the distribution.

· Improvement of design complexity, resulting in the traditional design process and design methods, as well as PC CAD tools are hard to fit the current technical challenges, therefore, EDA software tools platform from UNIX to NT platforms become industry recognized a trend.

High-speed digital system PCB solutions

Normally, when the signal interconnect delay greater than edge signal flip threshold 20% of the time, the Board of signal wires will show transmission line effects that the connection is no longer of lumping parameters appear mere wire performance, but rather the effect of rendering the distribution parameters, this design for high-speed design.

At the high-speed digital system design, designers must be resolved by parasitic parameter errors caused by the problem of turnover and signal distortion-instant order and signal integrity issues. At present this is high speed circuit designer must resolve bottlenecks.

Traditional physical rules-driven

We can be found in traditional high-speed circuit design, electrical rule set and set the rules of physics are separated. This brings up the following shortcomings:

· Early in the design engineers had to spend a lot of effort and a full front and rear side (that is, logical build-physical realization) analysis to planning needs to meet the electrical wiring strategies of physics.

· High speed effect is a complex issue that cannot be simple through wiring length and parallel line control to achieve the desired results.

· Designers will be faced with this dilemma, the physical with the illusion of constituents in the actual wiring rules do not apply in that he had to modify the repeated rules, so that it has practical value.

· When wiring is complete, you can use after validation tool for analysis. But if you find problems, the engineer must return to the design, structure or rules for adjustment. This is a loop of the redundancy processes. Will definitely affect product time to market.

· When the design has only a few dozens of root or root key line network, physical rules driven can good design tasks done; but when the design of hundreds of thousands of root root, or even network, physical rules-driven methods simply cannot fit design tasks.

Electronic technology development calls for new approaches, new tools, to solve design problems faced by the bottleneck. To resolve the physical rules-driven high-speed design flaws, and industry engages in high-speed digital circuit design and development of insight of EDA tools, three years ago made a live electrical rules-driven physical layout of the wiring of conception, from design concept to high-speed digital design process reforms.

New electrical interconnection integrated rule-driven:

· Internet-integrated real-time electric rules-driven method of a typical terms, i.e. in the physical layout of the wiring, Internet synthesizer real-time constraints under electrical rules, conduct analysis, extract meet designers require routing strategy, the design of a successful adoption. This approach will be integrated through the Internet and electrical requirements for accurate integrated physics, fundamentally eliminate physical rules-driven method of defects.

Internet-integrated processes are as follows:

Enter the tools · noise constraints timely order restriction rules

· Timing control layout, to meet the time-constraint requirements

· Implementation of signal integrity pre-optimization

· Board level comprehensive, ensure that critical network meet the electrical requirements

· Complete normal network cabling

· Optimization of routing.

Electrically driven methods can be effective in design and route quality assessment before, detection signal distortion, and determine the matching line network topology and appropriate terminal match structure and resistance. After completing the wiring layout, can be carried out after the validation, softPieces of oscilloscope intuitive detection waveform. For now the timing and distortion, comprehensive optimizer feature available wiring.

Gold tools portfolio and design processes

Now there are many EDA vendors can provide high-speed PCB design system EDA tools that help the user in this area effectively improve design quality, shorten the design cycle. In the application of electrical rules-driven method of EDA system board-level tools in the most representative of the United States when few MentorGraphics company ICX packages. It is the earliest comprehensive concept was presented, the Internet is currently the industry's most mature tool portfolio. This package is currently the industry's popular plug-and-play feature, it can be integrated in many manufacturers of PCB classic EDA design processes.

Mixed signal design solutions

Due to the design of miniature become fashionable, consumers demand high-performance, low-price goods, manufacturers to adapt to market competition, research and development personnel in the shortest possible period of time, developed a variety of different functional configuration of high-performance low-cost products that dominate the market. This gives designers a lot of new design challenges. For example: in the same block substrate using mixed techniques, and even radio frequency technology, to achieve the design of miniature and enhance product features. Swept the world of mobile phones is one of the most typical example.

The industry also has appropriate solutions-design group, parallel design, design reuse is derived and is the most typical strategy.

· Traditional serial design

The electronics engineer in complete front-end circuit design, to physical Board level designers complete back-end implementation. The design cycle is circuit design and Board-level design time.

Novel parallel design

In the design of miniature become mainstream thought and mixed technology is widely adopted, some serial design way behind the times. We must design methods for innovation, while taking advantage of the powerful EDA tools to aid the designer for design, in order to adapt the requirements of the market in a timely manner. As is known, we could not have become experts in all areas, it is not possible in a short period of time to complete all work best, fastest. The concept of the design team, in this context, and to a wide range of applications. Currently, many companies take a team approach to product development, and cooperation.

That is, according to the design complexity and function modules, the entire design is divided into different functional BLOCK block design by different developers in parallel for logic circuits and PCB design; and then in design top, each BLOCK block final design results in the "device" means import, synthesis of a complete board design. This method is called PCB design for reuse.

In this way we can see clearly that it can greatly shorten the design cycle, design time only available most BLOCK block design time and back-end interface connection handling time.

Tools, standardization and integration of third-party tools

There are many manufacturers engaged in electronic design automation (EDA) tools for development work, such as the Cadence, Synopsis, MentorGraphics the EDA tools for major suppliers; in addition, there are many other EDA vendors. EDA area involved is extensive, including networking, communications, computer science, aerospace, etc. Products involves system plate design, system simulation/MF Digital/Analog/RF simulation design, System IC/ASIC/FPGA design/simulation/verification, software/hardware co-design, etc. Any EDA suppliers are very difficult to provide various types of users of different design requirements of the most intense design process. From the market come to see the strengths of the Cadence IC board figure for product design and service, Synopsis of strengths products for logic synthesis, MentorGraphics the strengths of the products to PCB design and deep sub-micron IC design validation and testing, etc.

There is no doubt that the modern electronic design increasingly rely on EDA tools and techniques, EDA vendors adopt product standardization means to adapt to the user of this demand, many designers in his design process takes the strengths of companies that make up the best product design process.

The EDA manufacturers have increased their strengths product compatibility and integration of third-party products, to meet the needs of potential users.

Derived technology

To civilian products manufacturers, in order to meet the needs of different levels of users, often need to develop a different function, different grades of the product to own the market. In the past for the different functions of product development, we often use different design process to achieve, that is, with different design features of the different data production to realization of products on the Board. The disadvantage is cost increase and extension of the design cycle, while at the same time adding product people-the factors of unreliable.

Now many manufacturers use derived technology to solve the above problem, that is, with the same design process data derived from different series of products, so as to achieve lower costs and improve quality.

In order to adapt to the users of this demand, many ofthe EDA manufacturers have their own products increased derived rule checking (DRC) function, such as: of BoardStation Zuken-Redac MentorGraphics, etc, in case of BoardStation, it provides a complete, from the front-end circuit derived function module distribution, to the back-end of the physical layout rules check, produce different derived product list table of components, production and processing of data, data processing-painted and assembly drawings, etc., thus putting an end to this kind of design problems.