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Signal Integrity

Browse our library of resources to learn more about pcb design and signal integrity.

Oscilloscope Basics: A Beginner's Guide As electronics engineers, we’re incredibly lucky compared to other engineering disciplines. Not only are electronics rapidly evolving and expanding in use and functionality, but our test equipment gives us the greatest capabilities to diagnose and investigate the devices we have built. While all disciplines of engineering have fantastic suites of simulation tools, being able to see how something is performing in the real world can provide a lot Read Article

CAN-Bus: Introduction and History Take a look at our controller area network bus introduction. You'll learn about the history of CAN buses, their purpose, and how they were created. Read Article

How Material Characteristics Factor into High Speed PCB Signal Performance Evaluating laminates for a particular PCB implementation can be a complex, multilevel process, especially when it comes to the operation of key components on the board, such as high-speed differential pairs. This article will examine some of the factors that come into play with the evaluation process: materials with a low dielectric content versus materials that are low loss; comparing the advantages and disadvantages of each of them; taking into Read Article

Alternatives to a TEM Mode Transmission Line If you’re about my age or older, you probably remember being impressed with your old 14.4 kbps dialup internet. Those days seem long gone at this point as gigabit speeds are now commonplace. You can thank the advances by the signal integrity community and IC designers for getting us to this point. Still, one has to wonder whether current interconnect technologies are being pushed to their limits. Data rates on PCB interconnects have increased Read Article

EMI Case History — Noise Problems and Their Solutions — Part 2 In Part 1 of this article, I described an EMI noise problem occurring in a LCD touch screen display of an autonomous robot cleaning machine. In order to provide consulting services we needed to solve a problem which originated because of the ground and supply bounce in the leads of the IC devices that were incorporated into that display. In Part 1, I also described the type of equipment in which the operation problem arose, the origin of the Read Article

Modeling Copper Foil Roughness in Altium Designer's Impedance Profiler Advanced transmission line models for long interconnects require that designers include copper foil roughness calculations in order to determine accurate impedance. Without the right models or design software, you’ll be left to estimate the skin effect impedance, dispersion, and parasitics in your PCB. These models can be difficult to work with by hand if you’re not mathematically inclined, but the right design tools can be used to quickly Read Article

GNSS + LTE Asset Tracker Project, Part 1 In this week’s project, I’m building an LTE-based asset tracking system that could be used for a range of objectives, such theft prevention (and recovery), delivery or transit vehicle tracking, as well as predictive maintenance if data that is collected is paired with a suitable machine learning service. All of my previous projects have been two layer boards without any space constraints, but I miss building really compact high density circuit Read Article

Bluetooth 5.1 SoC vs. Module: Which is Best for Your Design? The list of features available in Bluetooth just got a little longer since the release of Bluetooth 5.1. Component manufacturers have taken this mobile technology to the next level for IoT devices by integrating wireless comms with an MCU for embedded processing. This is just another step in the continuous push to pack more functionality into a smaller footprint. If you want to incorporate a Bluetooth 5.1 SoC into your new product, you have two Read Article

How Copper Foil Roughness Affects Your Signals and Impedance The history of engineering, both electrical and mechanical, is littered with approximations that have fallen by the wayside. These approximations worked well for a time and helped advance technology significantly over the decades. However, any model has limits on its applicability, and the typical RLCG transmission line model and frequency-independent impedance equations are no different. So what’s the problem with these equations? Senior PCB Read Article

PCB Mountable Connectors: SMD vs. Through-hole When I designed some of my first boards, I was always working at DC or low speed, and any signal integrity problems from my connectors were an afterthought. These initial boards were for low frequency measurements of an electrochemical sensor. The only circuitry involved was a low-pass filter circuit with through-hole passives, a PCB mountable connector for a lab-grade power supply, and a parallel connection to an SMU. After learning the finer Read Article

How to Design Your PCB Test Coupon and What You Can Test As the operating speed of components has increased, controlled impedance is becoming more common in digital, analog, and mixed-signal systems. If the controlled impedance value for an interconnect is incorrect, it can be very difficult to identify this problem during an in-circuit test. Minor mismatches may not cause a board to fail, but it can be difficult to pinpoint incorrect impedance as the cause of any test failure, especially if correct Read Article

Modeling Copper Foil Roughness in Altium Designer's Impedance Profiler Advanced transmission line models for long interconnects require that designers include copper foil roughness calculations in order to determine accurate impedance. Without the right models or design software, you’ll be left to estimate the skin effect impedance, dispersion, and parasitics in your PCB. These models can be difficult to work with by hand if you’re not mathematically inclined, but the right design tools can be used to quickly Read Article

High-Speed Signal Routing: The 5 Important Constraints Your modern digital board is most likely classified as high speed, regardless of whether you looked at the datasheets for your components. Designing your board successfully will take some important steps when you begin your design. Aside from floorplanning and stackup design, your routing strategy will need to operate within some important constraints. After you capture your schematic as an initial layout and create an initial component Read Article

Transmission Line Impedance Measurement: Even vs. Odd Mode I still work on research in lasers, and pump-probe measurements are one way to examine how the electromagnetic field interacts with charge carriers in optical materials. With electronics, you won’t have to do anything as complex as a pump-probe technique for a transmission line impedance measurement. You’ll still need to examine how signals travel down a transmission line, and how they interact with the dielectric and load component. That’s just Read Article

How to Take a Phase Noise Measurement for High Speed Signals There are plenty of noise sources in your PCB, and phase noise can be one of those sources that is difficult to pin down in a real board. If you’re debugging a high speed board with high BER, then you’ll likely need to gather a phase noise measurement from the failing board section, or from your clock. Without getting too deep into the IC side of a system, phase noise may be an inherent property of the component you are using, such as the PLLs Read Article

Amplifier Stability at High Frequencies and Stray Capacitance Amplifiers are one of those critical components that make modern life possible. From wireless communication to power electronics, amplifiers need to run stably and predictably for these products to work properly. Stability analysis is one of my favorite topics in physics and engineering, and it always tends to crop up in places you would least expect. One of these places is in amplifiers. Any time-dependent physical system with feedback and gain Read Article

Near-field vs. Far-field EMI: What's Causing Noise Problems in My PCB? If you’re an antenna designer, then you’re likely familiar with all aspects of near-field vs. far-field radiation. Given the litany of radiated EMI problems that cause noise within and outside of an electronic device, one might suddenly realize their new product is acting like a strong antenna. To understand how EMI affects your circuits, it helps to understand exactly how near-field vs. far-field radiation from your PCB affects your ability to Read Article