Wireless Systems Design

Wireless-Systems Engineers Get Wired Into PCB Trends

Wireless-systems designers are being pushed to find low-cost ways to pack higher performance and greater functionality into smaller packages. For many, the solution is to combine digital, analog, and RF technologies. To reduce time to market, designers in different disciplines must therefore develop their designs concurrently. Such a technology combination also requires the use of a standard process that involves design capture, layout, verification, and release to manufacturing.

Until recently, electronic products like PDAs and cellular telephones had all been created by a small group of designers. To get the job done, these designers used a variety of design tools. Sophisticated design processes didn't exist. Plus, the need to maintain consistency throughout the processes wasn't a major concern.

With today's electronic-product design, successful products are faster, cheaper, and more reliable. They consume less power while flaunting more features. These products also occupy a smaller footprint. Lastly, they arrive to market in time to meet consumer demand.

Obviously, companies must make complex decisions in order to ensure a product's success. They must select cost-effective parts and conduct design collaboration across multiple sites. They also have to integrate business systems and handle aspects like high-speed design and advanced packaging and manufacturing. Companies are being forced to ask themselves how they can enhance their engineering skills while utilizing the latest electronic information. Typically, the answer is to redefine the design process to facilitate the creation of a larger system. This approach maximizes performance, quality, scalability, and affordability.

To further complicate matters, design-process changes are being influenced by new applications for the wireless Internet. These applications are being integrated into multiband handsets with stringent universal telecommunications standards like UMTS, Bluetooth, and GPS. For help with this integration, many companies are turning to the OEMs that specialize in wireless product design using powerful electronic-design-automation (EDA) tools. These tools boast sophisticated infrastructures that allow for concurrent design and library-management systems.

Meanwhile, OEMs have begun seeking their own cost efficiencies. One approach is to outsource significant parts of the product design to electronic-manufacturing-services (EMS) companies. Such companies handle design for manufacture, test, and component procurement. By outsourcing, the OEMs can focus on their products' intellectual property. This trend also supports component library sharing; collaboration through active real-time team design; library and design data management and manufacturing; and design-rule collaboration.

While OEMs refine processes, designers face their own obstacles. As printed-circuit-board (PCB) designers attempt to integrate mixed technologies, they must confront the following: higher frequencies, embedded passives, coupling parasitics, modeling interconnects, wider bandwidths, and high-speed digital signal processing. They must meet the requirements for seamless access to functional and signal-integrity verification for virtual prototyping. Faster design iterations and higher overall system performance also come into play.

RF designers must battle their own particular demons. To solve design tradeoffs in high-density, multi-layer packages, they need special transmission-line components and a flexible design environment. Such packages are generally not supported in standard PCB tools. In addition, wireless products with small form factors and low weight requirements necessitate that components be tightly integrated on the board. But microwave components tend to interfere with each other when placed in close proximity. Among the solutions for these types of problems are the use of buried radio-frequency components; distributed rather than discrete components; electromagnetic (EM) coupling analysis; and three-dimensional multi-layer design.

To continue on the design-for-performance trend, PCB designers are beginning to implement a design architecture that's already being used in the IC world. The multi-gigabit third-generation input/output (3GIO) architecture facilitates data transfer between ICs. Now, high-speed analysis is being performed on 3GIO boards with an advanced modeling language known as VHDL-AMS. This language combines both the digital and mixed-signal features of the 3GIO architecture with the traditional analog aspects of signal-integrity (SI) analysis.

Companies also are achieving first-to-market bragging rights with a rapidly changing design methodology called team design. Team design transforms serial PCB design processes with parallel ones. Project schedules then shrink while overall throughput and effective workload distribution increases. Practices such as 24-hr. design schedules, hierarchical partitioning, design reuse, and borderless design teams are key to the team-design methodology.

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