Signal Integrity

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

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

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

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

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

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

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

ADC Sampling Rate 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

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 Certification? When you need to pass EMC certification and your new product is being crippled by a mysterious source of EMI, you’ll probably start considering a complete product redesign. Your stackup, trace geometry, and component arrangement 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 easily place in your design, and that will help suppress EMI in Read Article

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 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 signalling 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 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 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 and differential signaling Read Article

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