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60 DESIGN007 MAGAZINE I JUNE 2020 • If a return path discontinuity exists, then the current tends to divert increasing the loop area, inductance, and delay. • A via that provides the connection between signal layers, referenced to planes of different DC potential, creates return path discontinuities. • If the reference planes are at the same DC potential, then they can be directly connected by stitching vias near the signal via transition. • If the planes are at different DC potential, then a bypass capacitor can be connected across the planes. • Two bypass capacitors are a much better solution, as this eliminates the transfer of power supply noise from one supply to another. • A slot in the plane under two or more nearby signal traces will cause return currents to overlap, resulting in some degree of crosstalk. • The secret for high-speed design is to construct the stackup in such a way as to make use of planar capacitance by making sure each VDD/VCC region is closely coupled to a continuous ground plane. • If thin dielectrics are used between the power and ground planes, split planes can have minimal impact on the quality of signal transmission. DESIGN007 Further Reading • B. Olney, "Beyond Design: Stackup Planning, Part 5," Design007 Magazine, July 2019. • B. Olney, "Beyond Design: The Proximity Effect," De- sign007 Magazine, March 2019. • B. Olney, "Beyond Design: Split Planes in Multilayer PCBs," The PCB Design Magazine, March 2015. • B. Olney, "Beyond Design: The Plain Truth About Plane Jumpers," The PCB Design Magazine, November 2012. • H. W. Johnson & M. Graham, High-Speed Digital De- sign: A Handbook of Black Magic, Prentice Hall, 1993. • Yuriy Shlepnev, et al. "Stripline With One Solid and One Split Reference Plane: SI List." Barry Olney is managing director of In- Circuit Design Pty Ltd (iCD), Australia, a PCB design service bureau that spe- cializes 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 at To read past columns or con- tact Olney, click here. National Instruments Corporation, the provider of a software-defined platform that accelerates the develop- ment and performance of automated test and automated measurement systems, announced it has entered into a definitive agreement to acquire OptimalPlus Ltd., a global leader in data analytics software for the semiconductor, automotive and electronics industries. The acquisition will expand NI's enterprise software capabilities to provide customers with business-critical insights through advanced product analytics across their product development flow and supply chain. NI and OptimalPlus serve highly complementary po- sitions in the semiconductor, automotive and electron- ics industries. NI test systems are used in semiconduc- tor manufacturing with OptimalPlus serving as a leading supplier of semiconductor manufacturing data analytics. Similarly, the NI automotive and electronics production test offerings are complementary to OptimalPlus' grow- ing automotive and electronics analytics business. Com- bining the strength of NI's software-centric approach with OptimalPlus' enterprise-level analytics software is expected to dramatically increase the value of test and manufacturing data, enabling product insights that will improve quality, efficiency and time to market for both NI and OptimalPlus customers. "The addition of OptimalPlus' data analytics capabili- ties will enable us to accelerate our growth strategy by increasing enterprise-level value for shared customers in the semiconductor and automotive industries," said Eric Starkloff, NI President and CEO. (Source: Business Wire) National Instruments to Acquire OptimalPlus

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