The PCB Design Magazine

PCBD-Aug2017

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48 The PCB Design Magazine • August 2017 • High-frequency harmonics can beat with the resonant frequency of the plane pairs creat- ing a rough wave effect which can cause total system failure • Solving signal integrity issues is always the best starting place to minimizing EMI. • To improve signal integrity, hence EMI, one needs to slow down the rise time of the sig- nal to reduce the high-frequency components. This is easily achieved by placing a termination resistor in series with the transmission line at the source. • It is always good design practice to allow space for a series terminator by adding a zero- ohm resistor to the critical interconnects to fu- ture-proof the design. PCBDESIGN References 1. Barry Olney's Beyond Design columns: Material Selection for SERDES Design, Mas- tering 'Black Magic' with Howard Johnson's Seminars, Signal Integrity Part 1, New Function- ality Improves Designer's Productivity, Plane Crazy Part 2. 2. Eric Bogatin, Signal and Power Integrity Simplified, Rule of Thumb #1: Bandwidth of a signal from its rise time. 3. Howard Johnson, Martin Graham. High- speed Digital Design. Barry Olney is managing director of In-Circuit Design Pty Ltd (iCD), Australia, a PCB design service bureau that specializes in board- level simulation. The company developed the iCD Design Integrity software incorporating the iCD Stackup, PDN and CPW Planner. The software can be downloaded from www.icd.com.au. To read past columns, click here. Design and nanomanufacturing have collided in- side a Northwestern University laboratory. An interdisciplinary team of researchers has used mathematics and machine learning to design an optimal material for light management in solar cells, then fabricated the nanostructured surfaces simulta - neously with a new nanomanufacturing technique. "We have bridged the gap between design and nanomanufacturing," said Wei Chen, the Wilson- Cook Professor in Engineering Design and professor of mechanical engineering in Northwestern's Mc - Cormick School of Engineering. "The concurrent design and processing of nano- structures paves the way to avoid trial-and-error manufacturing, increasing the cost effectiveness to prototype nanophotonic devices," said Teri Odom, Charles E. and Emma H. Morrison Professor of Chemistry in Northwestern's Weinberg College of Arts and Sciences. Researchers are currently in - terested in nanophotonic mate- rials for light absorption in ultra- thin, flexible solar cells. The same principle could also be applied to implement color into clothing without dyes and to create anti-wet surfaces. For solar cells, the ideal nanostructure sur- face features quasi-random structures, meaning the structures appear random but do have a pattern. To bypass the issues of nano-lithography, Odom and Chen manufactured the quasi-random struc- tures with wrinkle lithography, a new nanomanu- facturing technique that can rapidly transfer wrinkle patterns into different materials to realize a nearly unlimited number of quasi-random nanostructures. "Importantly , the complex geometries can be described computationally with only three param - eters — instead of thousands typically required by other approaches," Odom said. "We then used the digital designs in an iterative search loop to deter - mine the optimal nanowrinkles for a desired out- come." Next, the team plans to ap- ply its method to other materi- als, such as polymers, metals, and oxides, for other photonics applications. Simultaneous Design and Nanomanufacturing Speeds Up Fabrication WHEN LEGACY PRODUCTS NO LONGER PERFORM

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