Signal Integrity, In Practice

DDRx Memory Interfacing

Memory. Every system has it. Short-term, long-term, 2 nd level, static, dynamic, EPROM, graphic, internal, cache – but, by far, from an SI perspective the most common memory interface is DDRx. Double-Data Rate DDR memory arrived in the late 1990s, and has remained the dominant interface for decades. It has proven to be extensible and, now in its 5 th generation, DDRx has achieved a 20x increase in bandwidth. DDR memory occupies an important place in SI history. It was the force that drove ...

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Donald Telian, SiGuys - Guest Blogger 6/4/2019 Comments(0)

Measurement Correlation

I believe what simulators tell me. It’s funny because, throughout my career, I’ve met many who don’t. How is it that I somehow learned to trust them? Measurement Correlation. Over the years, taking the time to build, measure, and compare what I simulated taught me what’s good – and what’s not so good – about simulation. I developed confidence in my results and intuition that tells me when they’re suspect. Said another way, I learned to get value ou...

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Donald Telian, SiGuys - Guest Blogger 5/8/2019 Comments(0)

Simulating a Serial Link

And now one of my favorite topics: simulating a serial link. Good technology, good models, good margins, endless options. Yet how do I construct an accurate simulation? And what do I measure? Part of what makes this topic interesting is the variety of answers out there. And the almost infinite number of dials makes the task an engineer’s dream. In a world like that, how do I get started? …and how do I know when I’m done? How good is good enough? The Big Picture There are ...

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Donald Telian, SiGuys - Guest Blogger 4/15/2019 Comments(0)

Thinking About Power Integrity

Early February, over a foot of snow outside my office and the power is out. Good day to think about Power Integrity. Power matters. But why here in a series on Signal Integrity ? Good question. Power Integrity PI and Signal Integrity SI are intimately intertwined. Here are a few reasons why: PI and SI problems cause similar intermittent issues in systems PI problems can cause SI problems, and vice versa Because of 1 and 2 above, the problems are often solved by the same engineer Because of 1, 2,...

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Donald Telian, SiGuys - Guest Blogger 3/22/2019 Comments(0)

Understanding Trace Impedance

Author: Donald Telian , SI Guys - Guest Blogger The way high-speed signals interact with trace impedance has changed a bit over time, making the subject worthy of our attention. Thankfully, the importance - and even mechanics - of proper trace impedance is widely understood and agreed upon. So much so, the concept almost seems mundane – particularly against the rising importance of proper via impedance . However, I have found that engineers can benefit by improving their trace impedance in...

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Donald Telian, SiGuys - Guest Blogger 2/7/2019 Comments(0)

Managing PCB Crosstalk

Author: Donald Telian , SI Guys - Guest Blogger Crosstalk occurs when energy in one signal often called an aggressor couples onto another signal the victim adversely affecting the victim signal’s performance. The aggressor/victim language associated with crosstalk indicates danger is lurking, provoking a hardware engineer to consistent vigilance. How can we tame this foe? Or, more specifically, what causes crosstalk? …when does it become problematic? …and what can you do to ens...

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Donald Telian, SiGuys - Guest Blogger 1/16/2019 Comments(0)

7 Steps to Successful Serial Link Layout - Part 3

Author: Donald Telian , SI Guys - Guest Blogger This is the final installment in our 7 Steps series. If you’re just now tuning in, Part 1 detailed the primary problems we need to solve when implementing serial links: loss and discontinuities. In Part 2 we examined the pragmatic side of how those problems are handled during the layout process. Now in Part 3 we focus on issues that arise in manufacturing as well as opportunities related to software configuration – both important topics...

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Donald Telian, SiGuys - Guest Blogger 11/30/2018 Comments(0)

7 Steps to Successful Serial Link Layout, Part 2

Author: Donald Telian , SI Guys - Guest Blogger This is a continuation of my previous post detailing the 7 Steps required to successfully implement a serial link. While all 7 steps aim at controlling discontinuities and loss concepts introduced in Steps 1 and 2 , this post ventures into the pragmatic aspects of managing loss and discontinuities during the routing process. Ever wonder how a tiny via stub can destroy your signal? Read on. Step 3: Route Using Best Practices While it would seem self...

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Donald Telian - Guest Blogger, SiGuys 11/5/2018 Comments(0)

7 Steps to Successful Serial Link Layout, Part 1

Author: Donald Telian , SI Guys - Guest Blogger Over the past 15+ years I’ve been accumulating a checklist of items required for successful serial link layout. I refer to the list when a customer requests a design review of their implementation, without simulation. The swelling list also regularly appears as an Appendix in reports I write for other customers. So when we began developing our Pragmatic Signal Integrity course often co-taught by SiSoft and SiGuys at DesignCon , I thought Woul...

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Donald Telian - Guest Blogger, SiGuys 10/4/2018 Comments(0)

When Should I Simulate?

Author: Donald Telian , SI Guys - Guest Blogger This question is not asked as much as it should be. Companies that simulate routinely or never at all can both benefit by asking it. As a Consultant, asking and answering this question for my customer is part of my value add; defining effort and expense commensurate with the task at hand – no more, no less. Learning how to answer this question is one of engineering’s soft skills and the subject of this post. To be sure, inventors and pu...

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Donald Telian - Guest Blogger, SiGuys 9/5/2018 Comments(0)

Fixing Signal Integrity Issues in Software?

Author: Donald Telian , SI Guys - Guest Blogger Yes, you read that right. Unheard of? Read on. The history of electronics is checkered with many things that should have caught on, and others – like the internet – that surprised us with their ubiquity. This post is about something I expected to become one of the greatest boons for Signal Integrity SI : SerDes Equalization Settings SES, only accessible through software . I was wrong. You’d be surprised to learn how many of my cus...

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Donald Telian, SiGuys - Guest Blogger 8/9/2018 Comments(0)

Which Discontinuities are Small Enough to Ignore?

Author: Donald Telian , SI Guys - Guest Blogger A 60 mil via is too small to worry about, right? And that 20 mil solder pad - the signal certainly won’t see that, correct? If you work with high-speed signals, no doubt you’ve asked these questions and someone told you it depends. You might have your own rule-of-thumb RoT that helps you decide which discontinuities – or features – might impact signal quality. In this post I’m going to share my favorite rule-of-thumb r...

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Donald Telian, SiGuys - Guest Blogger 7/9/2018 Comments(1)

Understanding Via Impedance

Author: Donald Telian , SI Guys - Guest Blogger If you routinely give attention to trace impedance but are not accustomed to thinking about via impedance, this post is for you. Or, if you are paying attention to via impedance yet are unsure what dimensions will yield the right impedance, this help with that too. So, when should I use an 8 mil drill? Why should I care? Serial links can fail because of impedance miss-matches discontinuities . In practice, discontinuities are likely causing more pr...

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Donald Telian, SiGuys - Guest Blogger 5/23/2018 Comments(0)