Technical Articles

Modeling PCB Interconnects with Geometry and Material Parameters Variations for 56 Gbps Links

Measured S-parameters and cross-sections of PCB interconnects are used in this paper to identify the parameters of electrical models suitable for statistical analysis of interconnects with manufacturing variations. The constructed models reproduce observed effects of geometry and material properties variations on the loss, delay, and impedance, and they are suitable for yield analysis of interconnects with up to 56 Gbps signals.


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Why 2-Port Low-Impedance Measurements Still Matter

Measuring small resistance values is not trivial, but since 1861, when Lord Kelvin invented the Kelvin bridge,1 we at least have a solution for measuring very low DC resistances: the four-wire Kelvin connection (see Figure 1). We measure the resistance by sending a known current through the resistor and measure the voltage drop using separate wires.


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Battery Characterization for High Speed Signaling

The complex impedance value over frequency for an electric vehicle’s battery cell is a good measure of the internal cell temperature, the state of charge (SoC), and the state of health. Moreover, comparing the battery stack impedance with the single cell impedances can reveal upcoming high contact resistances. Read on for the details of how to do it.


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PCB Trace Current/Temperature Relationships and their Dependencies

The ability to analyze and predict the current/temperature effects of isolated traces is helpful, but the actual temperature of a trace may be different because of uncertainties in the actual trace thickness or board material thermal conductivity coefficient. This article traces the effort to see what PCB board parameters have the most impact in determining trace temperatures, followed by a look at related PCB design considerations. Read on to learn more.


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Why Are There So Many Standards?

There seems to be more standards every day, and some have rumored that there is a movement to merge or consolidate some existing standards. We will examine some of the standards and how they came to be. For starters, we will limit ourselves to three main types of standards in the industry: on-board or internal, input/output (I/O), and networking. I/O and networking are similar, but networking standards typically apply to longer distance links than I/O standards. There is, as often happens, overlap between these types, and some, such as PCI-express, have standards that apply to more than one of them.


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Silicon Photonics: Past, Present and Future

Optoelectronic industry designers have traditionally used discrete optical devices for transceiver designs. The process requires manual integration of discrete free-space optical components such as lasers, modulator, photo detectors, isolators, MUX/DE-MUX, lenses in the form of optical gold box sub-assemblies such as transmit optical sub-assembly (TOSA).


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