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Signal Integrity

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

Should You Use Your Power Plane as a Return Path? Power planes and ground planes are important for more than just distribution of supply and return power. When defining reference planes, both with impedance controlled routing and in managing return paths, your stackup might force return currents to pass into a power plane before being coupled back to a ground layer. Let’s take a look at some good practices for controlling return paths in your PCB with a power plane as a return path. Signal Read Article

The Case Against Orthogonal Trace Routing in Multilayer PCBs Can you spot the orthogonal trace routing in this complex board? Neither can I... I occasionally see questions on forums, some blog posts, and even application notes that continue to recommend the use of orthogonal routing, usually in 2-6 layer boards. When looking at application notes, I tend to default to Rick Hartley’s advice and try to think about this advice in context. Unfortunately, recommendations in application notes are not always taken Read Article

Reflecting on Your Design— What are Reflections and What Do They Do to a Signal? Part One In describing what happens when an electromagnetic field or wave is traveling on a transmission line, we often talk about the various things that can disrupt that wave. Among the most common of these things are reflections. Part 1 of this article will describe what reflections are and how they are caused. The second part will discuss what they do to a signal. Then, a separate article will address how reflections are controlled by terminations Read Article

The Fundamentals of High Speed SerDes Design High speed SerDes design goes far beyond computer peripherals The challenges in high speed SerDes design filter right down to the PCB level and are all about backplane/daughtercard design, transmission line layout, selecting proper equalization schemes, and much more. This even gets down to the fundamentals, where stackup and power integrity become critical when driving transmitters and receiver ICs. If you’re designing a PCB as part of a SerDes Read Article

Some Pre-layout Power Spectrum Analysis Tips in Altium Designer Take advantage of your simulation tools before test and measurement. Here I want to expand a bit on the power spectrum analysis features in Altium Designer^®. In a previous post, we looked at working with simulations involving a frequency modulated signal fed into a nonlinear component (an NPN transistor). In this simulation, we ended with the Fourier spectrum at the load resistor for various values of base voltage/current. In the time-domain Read Article

DDR5 PCB Design and Signal Integrity: What Designers Need to Know Development of the world’s first DDR5 RAM was announced just 1 year ago, with peak speed of 5200 MT/sec/pin (compare that to 3200 MT/sec/pin with DDR4) at 1.1 V. Full-scale production is set to begin in 2020, and demand for this new generation of memories with 8, 16, and 32 GB capacities will quickly outpace that for earlier generations. JEDEC rates DDR5 speeds up to 6400 MT/sec/pin, with bandwidth increased up to 300 GB/s. The faster speeds Read Article

Substrate Integrated Waveguide Routing for mmWave PCBs A substrate integrated waveguide acts similar to optical fibers The applications of mmWave signals used to be confined to defense, but now mmWave systems are becoming more common. You can thank car radar, UAV radar, upcoming rollouts of 5G, and current research on 6G for bringing mmWave technology into the mainstream. Routing with mmWave signals has forced designers to rethink their routing practices and interconnect designs. This has motivated Read Article

Parasitic Extraction with an Electromagnetic Solver in PCB Routing Keep your signals synchronized with parasitic extraction in your PCBs Parasitic extraction: the integrated circuit design community must grapple with this task on a delay basis, especially once gate features are reduced below ~350 nm and chips run at high switching rates. The PCB community also has to deal with this idea in order to better design power delivery networks, interconnects with extremely precise impedance, and properly quantify Read Article

High Speed Routing Guidelines for Advanced PCBs You can create this advanced board with these high speed routing guidelines for advanced PCBs Newer designs are continuing to get faster, with PCIe 5.0 reaching 32 Gb/s, and PAM4 pushing signal integrity and speeds to the limit. Proper interconnect design must account for the lower noise margins of advanced devices, impeccable power stability requirements, and much more to ensure signals can be received properly. With advanced devices running at Read Article

MIPI Physical Layer Routing and Signal Integrity MIPI physical layer routing (C-PHY) is typically used to connect these smartphone cameras to a processor. When most designers talk about routing standards, particularly for advanced devices, they typically refer to differential routing standards (e.g., LVDS) that enable high data rates. These signaling standards have proliferated computers, networking equipment, smart electronics, and other areas, and they have been critical for operating with Read Article

EMI from Heatsinks and What You Can Do About It Selecting the right heatsink can help you keep your system cool and prevent EMI. While it may not be obvious, or while most designers may not think to check, heatsinks can generate EMI when they are connected to a switching element. This is a common problem in power supply design, and whenever a heatsink is placed in contact with a component that switches with high current draw at high frequency. Reducing EMI from heatsinks requires balancing the Read Article

Some Techniques for Suppressing DC-DC Converter EMI in IoT Products This Li ion battery is most likely connected to a switching regulator to provide stable power. Suppressing EMI susceptibility in IoT devices from various sources is critical to ensuring your new product will work as designed. Similarly, your IoT product should limit spurious emissions if you want it to comply with EMC regulations. Among the various sources of radiated EMI from your next product, EMI within the device itself should also be Read Article

Load Line Analysis for Nonlinear Circuits in Altium Designer If you’re in the business of analog circuit design, then you’ll likely need to run simulations of your system to determine its functionality. Linear systems are rather intuitive, even in the case where strong feedback becomes an important determinant of stability. With nonlinear circuits, this can get more complicated, and it’s not always easy to see how the system operates unless you have some experience with similar systems. Transistors and Read Article

Splitting Planes—The Good, The Bad And The Ugly Splitting planes or making plane cuts is another one of those technical issues wherein there is a lot of conflicting information. Some say it’s a good thing to split planes; others say you can make plane cuts in both ground and power planes, some say you make cuts only in power planes, and others say to avoid plane cuts altogether. This article will debunk the myths surrounding split planes, provide evidence as to when they are useful, and Read Article

Plated Through-Hole Vias in mmWave PCBs Should you plate your through-hole vias in mmWave PCBs? Recently, I received a question from a designer at a startup wondering about proper use of plated through-hole vias in mmWave PCBs. It got me thinking that I neglected to mention this point in a previous blog post, although space in these posts can be limited. This is a fair question, both when dealing with microwave/mmWave frequencies, and when working with high speed digital signals. At Read Article

SMPS Circuit Design: Which Switching Frequency to Use? Power supply on a network switch Power electronics and switched-mode power supply (SMPS) designers should know that working with higher switching frequencies can lead to higher switching losses in your system. However, the push to miniaturize power supplies, and the components that go into them, compels designers to work with higher switching frequencies in their SMPS circuit designs. This then creates problems where switching losses and noise Read Article

Frequency Modulation Simulation in Altium Designer When working with analog signals, you need to ensure your device is operating linearly in order to prevent problems like harmonic distortion during operation. Nonlinear interactions in analog devices lead to distortion that corrupts a clean analog signal. It may not be obvious when an analog circuit clips just from looking at your schematic or datasheets. Instead of tracing through your signal chain manually, you can use simulation tools to get Read Article