Signal Integrity

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

xSignals in Altium Designer Signal Integrity Stimulus Design Rules Basics of Signal Integrity Analysis

Modeling Copper Foil Roughness in Altium Designer's Impedance Profiler

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 Routing Constraints

High-Speed Signal Routing: The 5 Important PCB Design 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 PCB design constraints. After you capture your schematic as an initial layout and create an initial Read Article

Transmission Line Impedance Measurement: Even vs. Odd Mode

Transmission Line Impedance Measurement: Even vs. Odd Mode If you need an accurate transmission line impedance measurement, here are the important values you need to use in your next board. Read Article

Phase noise measurement with spectrum analyzers

How to Take a Phase Noise Measurement in a PCB There are plenty of noise sources in your PCB, ranging from thermal noise to EMI received from external sources. Phase noise is one noise source that occurs in analog signal sources like reference oscillators and frequency synthesizers. This type of noise affects the timing of analog signals and it arises due to contributions from other noise sources. If you’re debugging a high frequency board with a reference oscillator, then you might need to Read Article

Will these amplifiers be stable during operation? Here’s what you should know about amplifier stability in your PCB.

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 radiation from a smartphone

Near-field and 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

ADC Sampling Rate and Layout for Mixed Signal Boards

Sampling Rate of ADC and Layout for Mixed Signal Boards Whenever you’re selecting an ADC, whether it is built into an MCU or as an external component, the sampling rate is a prime consideration, as it will determine how well you can reproduce a measured signal. RF applications, analog sensor boards, and other mixed-signal devices will need at least one ADC with an appropriately chosen ADC sampling rate. If you’re designing with a mixed-signal board, you’ll need to balance the required signal bandwidth Read Article

Everything You Need to Know About Ferrite Beads

Everything You Need to Know About Ferrite Beads As noted in my previous blog regarding PDS design, the whole power supply conundrum is one that has been plagued over the years with a number of erroneous rules-of-thumb; “black magic” design rules and confusion as to what does or doesn’t work. One of the most controversial topic areas focuses on the use of ferrite beads as a means of controlling and containing EMI. There is conflicting information concerning the use of ferrite beads and it is Read Article

DIFFERENTIAL SIGNALING IN PCB DESIGN

DIFFERENTIAL SIGNALING IN PCB DESIGN The primary reason that differential signaling is dominating the digital world is that far higher data bandwidths can be achieved over a pair of wires than with parallel, single-ended signaling protocols. The Internet as we know it would not be possible without it. This information is intended to clear up any confusion about differential signaling. INTRODUCTION Differential signaling has evolved into the primary method for connecting logic Read Article

Length matching with differential pairs is like walking a tightrope

Differential Pair Length Matching: Best Practices for Signal Integrity Take two signals and send them down a parallel bus or differential pair. How can you be sure the downstream receiver will latch to your signals? If your signals don’t arrive at the same place and at the same time, then gates in your receiver won’t latch at just the right moment. This delicate balance can be like walking a tightrope across a cliff, and it can be difficult to maintain differential pair length matching by eyeing your trace lengths Read Article

What Types of EMI Filters are Best for Passing EMC Testing?

What Types of EMI Filters are Best for Passing EMC Testing? When you need to pass EMC testing and your new product is being crippled by a mysterious source of EMI, you’ll probably start considering a complete product redesign. Your stackup, layout/routing, and component placement are good places to start, but there might be more you can do to suppress specific sources of EMI. There are many different types of EMI filters that you can place in your design, and the right filter can help suppress EMI in a Read Article

Thermal Relief Via Design for Proper Impedance

Thermal Relief Via Design for Proper Impedance Following DFM guidelines is a critical requirement for ensuring high yields and defect-free boards during fabrication. Most DFM guidelines are well-grounded and do not generally interfere with signal integrity. In the event that they do, most EDA tools include features that can help ensure you won’t sacrifice signal integrity for manufacturability, and the two design aspects often go hand-in-hand. One aspect of routing, signal integrity, and Read Article

Transmission Line Impedance: The Six Important Values

Transmission Line Impedance: The Six Important Values When looking through the various transmission line impedance values, characteristic impedance and differential impedance generally stand out as the two important values as these are typically specified in signaling standards. However, there are really six transmission line impedance values that are important in PCB design. Sometimes there are seven, depending on which textbooks or technical articles you read. Characteristic impedance equations Read Article

NB-IoT Antenna Design and Layout for Your PCB

NB-IoT Antenna Design and Layout for Your PCB With all the possible wireless communication protocols available for use in a mobile device, it can be difficult to keep them straight. Narrowband IoT (NB-IoT) and LTE-M are two low-bandwidth protocols that provide remote monitoring capabilities over several miles of distance. While the data rates are quite low in both protocols, these protocols are excellent choices for lightweight embedded systems, such as small sensor arrays, industrial or Read Article

Single-Ended Switching Versus Differential Signaling

Single-Ended Signal vs Differential Transmission Just about every place you look these days when you talk about high-speed PCB design, the signaling required for a product is, by default, differential signaling. But, differential signaling was not always at the forefront of product development. The original method of moving data was single-ended signaling. And, in some instances, it is still in use today. This article will describe the differences between single-ended vs differential Read Article

With so many possible noise sources, it can be difficult to tell them apart.

Is it Simultaneous Switching Noise or Crosstalk? How can you distinguish simultaneous switching noise and crosstalk? Take a look at the difference between these two signal integrity problems in this article. Read Article

Antenna isolation in newer cell phones goes beyond simple shielding structures.

Designing for Antenna Isolation in Your Wireless System Antenna isolation is designed to prevent interference between antennas and ensure diversity in wireless systems. Read Article