Ensuring Signal Integrity Throughout a Channel

Electronic devices — with well-designed signal integrity (SI) — have transformed the way we communicate, work, learn and entertain. Around the globe, we find smart phones, fiber-optic and wireless networks, pocket-size computers, LED screen displays that mimic paper and unmanned aerial vehicles (UAVs) that deliver packages. Automobiles are filled with electronics that control engine functions, keep wheels from skidding, avoid accidents, direct our travel routes and, now, drive themselves. Aircraft are equipped with radar, fly-by-wire systems and airborne communications. And the innovations keep coming…

deep channel analysis for signal integrity

The opportunity to differentiate a product with electronics has never been so pronounced. At the same time, the consequences of product failure can be catastrophic — for both end-users and manufacturers. The cost of a single product recall is estimated at $8 million-plus, and can be exponentially greater if the brand is devalued as a result.

With the stakes so high and the devices more powerful and portable, electronics designers are wrestling with new signal integrity challenges. Twenty years ago, SI issues were more easily identified and solved. At slower speeds and edge rates, electrical signals would travel down wires to their destinations and perform specific tasks — without significantly affecting other circuit components. Now these signals travel at greater speeds, with edge rates of just a few picoseconds, and with increased bandwidth.

When a higher-frequency signal is sent through the more densely packed space of increasingly smaller devices, it not only reaches its destination, but also resonates and emits electromagnetic (EM) fields that interfere with other components in the product and other, nearby devices. In complex systems such as cars and airplanes, electronic and electromechanical components are developed by multiple vendors, increasing the opportunity not only for noise, but also for failure.

Within a channel, any loss of signal-to-noise ratio will impact performance. Data rates are operating in excess of 28 Gbps, and accelerating to 56 Gbps and beyond. Industrywide, we’re also seeing the adoption of differing modulation schemes such as PAM4 to increase bandwidth, which places additional strain on signal-to-noise ratios. Routing high-frequency signals through high-speed, more compact systems creates a variety of signal integrity issues, including reflection concerns, crosstalk degradation, ISI and power/ground noise impact. All resulting in diminished margins.

We need simulation models and workflows that account for increased signaling speeds and frequencies flowing through ICs, packages and printed circuit boards (PCBs) with thousands of nets and hundreds of components. Circuit simulation, once the go-to for electrical engineers no longer cuts it. Optimizing high-performance systems requires examination of component interactions at the chip, package and board levels — simultaneously. An integrated circuit, for instance, may perform flawlessly at the package part level. When placed on a highly dense PCB, that same circuit may produce unexpected behavior due to complex parasitic interactions.

ANSYS SIwave signal integrity simulation

ANSYS SIwave near-end crosstalk result for this design
showed anomalous behavior.

The ANSYS Electronics platform is helping our customers address thermal-, signal- and power-integrity issues throughout the design process. It enables electromagnetic analysis at all levels and can pinpoint hard-to-detect interference. Learn how engineers at Samtec, Inc. leveraged simulation to design and optimize a next-generation, high-performance interconnect solution across the channel, and how Interconnect Engineering, Inc. used the platform to isolate a hidden source of crosstalk on a DDR3-800 PCB in the article A Via Runs through It.

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