关于作者

Jason J. Ellison

Jason J Ellison 于 2017 年 12 月获得宾夕法尼亚州立大学电气工程理学硕士学位。
他受聘为信号完整性工程师，负责开发高速互连、实验室自动化技术和校准技术。他的兴趣是信号完整性、电源完整性和嵌入式系统设计。他还为《The Signal Integrity Journal》等期刊撰写技术类发表作品。
Ellison 先生是活跃的 IEEE 成员和 DesignCon 技术程序委员会成员。

最新文章

Interference Amplitude Distortion

Interference Amplitude Distortion I’ve talked about COM and channel analysis in previous blogs, and I’d like to continue the discussion with more visual aids and some example code to enable readers to do some analysis themselves. To start, let’s review what COM is and a high level overview of how COM is calculated. COM is a signal-to-noise ratio of voltage at a point in time. The point in time is the sampling point, and the available signal is the voltage of the pulse response at 阅读文章

Expert Analysis of Measured S-Parameters

Expert Analysis of Measured S-Parameters Read to learn an introduction about S-parameter analysis. This article covers how to identify port maps, what insertion loss and return loss looks like, how the various S-parameters look in the time-domain, and some additional analysis techniques to use when data mining S-parameters. 阅读文章

S-parameter causality

How to Verify Signal Integrity Causality in S-parameters We often hear about how time-domain simulations require causal S-parameters. We’ll explore what S-parameter causality means and what non-causal S-parameters do to channel analysis. 阅读文章

Getting Through PCB DFM

Getting Through a PCB DFM Check If you’re reading an Altium Blog, it’s probably safe to say that you’ve either designed or fabricated printed circuit boards. If you’re like me, sending a design to fab is a bittersweet experience. On the one hand, you’ll soon have your hands on the hardware you’ve been working hard to design. But on the other hand, you know the fabrication site is going to send a list of PCB DFM requests, and that’s never fun. In this article, we’ll discuss the 阅读文章

Evaluating Concord Pro

Evaluating Concord Pro Altium Concord Pro™ as a standalone product and brand name has been discontinued and the capabilities are now available as part of our Altium enterprise solutions. Learn more here . I’m working on several projects that require new PCB assemblies, and this presented a great opportunity to try Altium’s new product: Concord Pro™. Concord Pro is a component management system which makes component creation and organization much easier than using the 阅读文章

Tricks of the Trade: Signal Integrity Devices

Tricks of the Trade: Signal Integrity Devices As with any job, Signal Integrity engineers use niche tools. SI tools are often thought of as S-parameter viewers, 3D EM solvers, or measurement equipment. These tools have one thing in common: analysis. What about the devices that SI engineers deploy to make their lives easier? In this article, I’ll discuss three devices to save time and money: multiport test cables, RF switches, and the old RC filter. Multi-port RF Cable Assemblies Today’s high 阅读文章

Reading Impedance Profiles of High Speed Backplanes

Reading Impedance Profiles of High Speed Backplanes Impedance remains a confusing topic in the signal integrity community. By definition, impedance is the ratio of voltage to current. That doesn’t really paint a clear picture to anyone. Getting more specific, the term impedance can mean several things. Step response of broadband reflection coefficient in ohms Impulse response of broadband reflection coefficient in ohms Time domain Z-parameters Frequency domain Z-parameters Signal Integrity 阅读文章

Validation Structures for Signal Integrity

Validation Structures for Signal Integrity Let’s say you’ve just received a populated switch or GPU PCB from your favorite PCB fabrication and assembly site. You sit down at your computer and start up your GUI or console to begin transmitting data. Trouble begins—the protocol to bring up the link isn’t working. What do you do? Checking the voltages and jumper positions is easy enough, but what about the signal integrity of your channel? Assuming that you did all of the required 阅读文章

Insertion Loss Deviation or Intersymbol Interference Noise?

Insertion Loss Deviation or Intersymbol Interference Noise? In a previous blog , I discussed how channel quality is quantified by eye patterns [1]. There, it is explained how eye patterns are created from the thru S-parameters only. So, if you are using the thru S-parameters alone, do reflections even matter? Intuitively, it would seem like they don’t matter since they are not directly used to calculate the eye pattern. S-Parameters Still Matter But, of course reflections matter! Reflections cause signal 阅读文章

Kramer-Kronig’s Relationship to PCBs

Kramer-Kronig’s Relationship to PCBs The Kramer Kronig relationship is basically a way to go back and forth from the real and imaginary parts of a function. That’s it. So when someone says “blah blah blah must conform to the Kramer-Kronig relationship”, it’s a statement that is stating the obvious. Similar statements are, dogs must be part of the canine family and thus canis genus or petrol must have come from petroleum deposit on earth. Both correct and mildly interesting 阅读文章

DFSI: Stripline Differential Impedance Calculation Made Easy

DFSI: Stripline Differential Impedance Calculation Made Easy As a PCB designer, you may hear your signal integrity overlords dictate controlled impedance with a specific value and tolerance. As someone who has requested these things, I know designers have trouble with implementing this in their trace geometry. This article details what impedance is, how it is calculated, and a practical way for PCB designers to determine the proper geometry for their application. When designing high-speed serial circuits 阅读文章

DFSI: Overcoming Channel Loss

DFSI: Overcoming Channel Loss In a previous article , we established that loss is one of the primary signal integrity challenges to overcome. In this article, we’ll talk about the sources of loss, what you can do about them, and an often neglected aspect of loss. There are various options for reducing loss, in this article I’ll discuss how to: Change your architecture to orthogonal or cables Use better PCB materials with lower DF resin and smoother copper Add active repeaters 阅读文章

Design For Signal Integrity

Design For Signal Integrity When we design PCBs, we start with setting up our Design For Manufacturing (DFM) rules in an EDA tool. However, it is likely that our Signal Integrity rules are the last thing we think about. In this blog, we’ll explore how to incorporate Design For Signal Integrity (DFSI) into our DFM routine. Design For Manufacturing Before discussing DFSI, let’s first review DFM criteria. The most driving criteria for DFM comes from the PCB’s IPC 阅读文章

Channel Operating Margin Isn’t So Bad

Channel Operating Margin Isn’t So Bad What is a COM anyway? Channel Operating Margin, or COM, isn’t well understood. Since it isn’t well understood, many people doubt it really means anything. After all, how can channel quality be represented by just one number in decibels? It turns out, COM is actually the latest evolutionary step in a long progression of channel validation techniques using eye patterns. This blog will trace the evolution of COM back to its roots and put meaning to 阅读文章