Effective strategies for calculating rogue wave noise levels.
For about 20 years, PDN design and analysis focused on the target impedance method. In recent years, additional considerations surfaced about rogue waves, but more as a general discussion. Here we present a new design/analysis method for estimating rogue wave amplitudes we can compare against the digital chip specs for design verification.
Electrical designs must be verified against possible worst-case conditions. For power distribution networks (PDN digital chip supply rail), this is typically done by comparing their impedance profiles against a target impedance requirement. From recent research and publications, we know the target impedance method for analyzing PDN design does not always predict the worst-case noise voltage because different frequency components of the chip supply current load steps can superposition on top of each other. This is sometimes called rogue waves (RW).
Written by Douglas Brooks, Ph.D., Johannes Adam, Ph.D., and Ulisses Castro
Category: Features
Signal traces internal to the board change temperature along their length, changing resistance.
In our recent book,1 an image shows how heat from a relatively hot trace flows downward through the board (FIGURE 1). What is important to recognize here is how little horizontal heat dispersion there is. The heat seems to flow straight down. What thermal images like this obscure is the relative horizontal and vertical scales. The horizontal width in this image is 50mm, while the vertical height is less than 2mm. Not enough room is underneath the trace for much horizontal dispersion. Consequently, the temperature of the bottom layer of the board directly under the trace is only a few degrees cooler than the temperature of the top layer, regardless of what is beneath the top layer.
RIT and industry have developed a novel curriculum for teaching PCB design. Is this the start of a college trend?
We are always interested in the approaches being taken to recruit and train the next generation of engineers. Readers may recall last summer we did a podcast with a group of recent graduates from the Rochester Institute of Technology’s Capstone program. There, the students conceive, design, source and build electronics hardware as part of a senior project. It’s truly a great way to immerse themselves in what a career in our industry could look like.
What we didn’t mention was RIT is launching another hands-on program. This one focuses on printed circuit board design. The first class started in January with 25 students. Chris Banton, director of marketing at EMA Design Automation, and Dr. James Lee, acting chair of the Electrical and Computer Engineering Technology department at RIT, explained what spurred the program and what it hopes to accomplish.
An Ohio community college breaks the mold with an applied bachelor’s degree in electronics manufacturing.
In my three decades in electronics engineering, perhaps the only thing that never changes is the need for more skilled workers. No matter the state of the economy or the geography, having knowledgeable and competent engineers and operators is always critical, and there are never enough of either.
But while the tension is notable between industry and academia over who is responsible for preparing the next generation of workers for specific tasks, some schools are quietly taking the lead by putting in place programs that include true hands-on training in printed circuit board manufacturing.
I’m talking specifically about Lorain County Community College. Lorain is in Northeast Ohio, about 30 miles west of Cleveland.
“Chips don’t float,” the saying goes, but it’s up to the PCB industry to push its message to Washington.
It’s hard to believe now, but veterans of the printed circuit board industry will remember when the US was neck and neck with Japan as the largest PCB manufacturing market. It peaked in 2000-2001 with sales north of $10 billion each year and close to a 30% share of the overall market.
How things change.
Today, US domestic PCB manufacturing output is around $3 billion, and its share of the global market is in the mid-single digits. Meanwhile, China has surged ahead of the pack, as more than half the bare boards produced each year are built on the mainland. Moreover, nations like Vietnam that didn’t even register a decade ago are now larger than the US market.
Ed.: This is a special feature courtesy of Binghamton University.
Next-gen chips will be powered from below. As transistors continue to be made thinner, the interconnects that supply them with current must be packed closer, which increases resistance and power. In processors, both signals and power reach the silicon from above. Arm researchers have developed a technology that separates those functions, saving power and making more room for signal routes. The signals travel along the copper traces of a PCB into a package that holds the SoC, through the solder balls that connect the chip to the package, and then via on-chip interconnects to the transistors. These interconnects are formed in layers called a stack. It can take a 10- to 20-layer stack to deliver power and data to the billions of transistors on today’s chips. (IEEC file #12450, IEEE Spectrum, 9/2/21)
Using liquid metal to turn motion into electricity, even underwater. North Carolina State University researchers have created a soft, stretchable device that converts movement into electricity and works in dry and wet environments. The heart of this energy harvester is a liquid metal alloy of gallium and indium. The alloy is encased in a hydrogel with the water containing dissolved salts (ions). The ions assemble at the surface of the metal, which induces a charge in the metal. Increasing the area of the metal provides more surface to attract a charge. This generates electricity, which is captured by a wire attached to the device. Researchers found that deforming the device by only a few millimeters generates a power density of approximately 0.5 mW/m-2, comparable to popular classes of energy harvesting technologies. (IEEC file #12449, Science Daily, 8/28/21)
