White Papers

Method of Modeling Differential Vias

Accurate, models for vias in a multilayer circuit board are necessary to predict link performance in the GHz regime. This white paper describes a methodology to build a high bandwidth, scalable first approximation circuit model using simple transmission lines of long vias typically used in thick backplane designs.

Authors: L. Simonovich, E. Bogatin and Y. Cao, April 2009

EMC Shielding Simplified

Provides basic physics and concepts about how EMC shielding works, what materials are used, how they are used, and what processes go into protecting devices. The paper details how to make shielding work properly, some typical shielding failures, and how to solve those failures.

Author: VTI Vacuum Technologies and William D. Kimmel, emiguru.com


Ceramic Chip Antennas vs. PCB Trace Antennas: A Comparison

The purpose of a trace antenna on a printed circuit board (PCB) is to provide a method of wireless communication. The trace is laminated on the PCB's surface or, in some cases, the traces can occupy several layers of a multilayer board and vias are used to interconnect the traces on each layer. A ceramic antenna is a separate component that is attached during the final stage in the surface mount process. The article discusses the advantages and disadvantages of each type of antenna and which antenna best fits specific situations.

"Multi-purpose machine-to-machine devices require a high-quality radio interface that will operate in the Zigbee, ISM, and cellular bands including LTE, bands which lie between 700 and 2500 MHz. A trace antenna on a PCB is often the first type of interface considered for one of these applications. However, using a ceramic antenna can be a good or even better alternative," says Lifländer. "In these products, size constraints are more stringent and multiple antennas often need to be placed inside the same device, resulting in the need for high immunity between the antennas. Ceramic antennas enable flexibility in design, overall cost savings in the final product, have fewer problems with interference, and provide improved performance over trace antennas. This paper delves more deeply into these issues.

Author: Jouni Lifländer, RF designer, Pulse Electronics

There are three driving forces that are radically changing CAD library construction. The first is lead free solder. The next is metric units. And lastly is Component Manufacturer Chaos. This term describes component manufacturers who no longer follow JEDEC packaging standards and are leading the way for new component package development. It seems as though the constraints of standard package data have been thrown out the window and new unique electronic device packages are emerging on the market at light speed. These challenges will continue to impact CAD library development and maintenance as we move forward.

Author: Mentor Graphics

Selecting the Right Cable System for Your Environment

A systematic approach design engineers can follow to ensure a cable system will provide reliable performance in demanding environments and mission-critical applications. The paper discusses electrical, mechanical, environmental, and application-specific constraints that affect cable performance. Advantages and disadvantages of typical materials used in cable construction are explained, including an explanation of the testing and data analysis a manufacturer should perform to verify its cable will perform in a specific application. Cost considerations and ramifications of cable failure are also included.

Author: Gore & Associates

Leveraging FPGA in PCB System Designs

FPGA devices create compelling business drivers generating a tidal wave of FPGA adoption for the implementation of system PCB designs. Obviously, the time to market advantages and capacity/performance characteristics of FPGA devices have delivered on the promise for a viable alternative to more capital resource intensive custom IC/ASIC solutions as well as a successful consolidation vehicle for standard “off the shelf” components in system design creation.

Author: Mentor Graphics

Power Integrity in Systems Design: Part 1

This paper discusses the fundamental requirements of power integrity (PI), and the most important concept used in PI, the network impedance. It answers the questions commonly asked by digital designers on how a power delivery network (PDN) is represented, how PDN impedance is generally defined, what the target impedance is and its effective range, and the factors affecting impedance analysis. The paper also addresses the contributions of IC current, package inductance, and on-die capacitance to PDN impedance analysis.

Author: Mentor Graphics


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