Features

Or should we just isolate noisy signals?

There are several theories about whether a differential pair should be routed with tight coupling or loose coupling. There must be some science that can be drawn on to arrive at a rule set that makes best use of layout time, while optimizing the signal integrity of a differential pair. This article explores the advantages of tight and loose coupling.

A known industry speaker says, “Everybody knows tight coupling is best for differential signaling.” This is stated in a tone of voice that implies those who don’t know this might be lacking. I sometimes say I am from Missouri, which is the “Show-Me State.” If the need for tight coupling is true, perhaps there is some proof. I am still waiting to see it. The following discussion will look at a tightly coupled differential pair and the same pair loosely coupled.

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Or does it distract from the actual need of the signaling protocol?

Much engineering time is spent on designing differential signaling circuits to maintain a differential impedance between the two sides of the differential pair. A similar amount of time is spent measuring the final PCBs to ensure the differential impedance specification is met. The most common differential impedance target is 100Ω. A fair question is whether this impedance requirement is necessary. Once differential signaling is understood, it will be seen as unnecessary and distracting from the actual need of the signaling protocol. This article will clear up this confusion.

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Stephen Chavez

In this month’s column, we’ll take a first look at the new Printed Circuit Engineering Association (PCEA), including an overview of membership and why we established the organization. We’ll also look at the mission of PCEA, and how it will unfold to the industry.

Membership. PCEA is an international network of engineers, designers, and specialists related to printed circuit development. We are a mixed group of individuals that covers the entire product development cycle. There are no limitations or restrictions as to who can become a member. Membership is free and open to all those interested in gaining and sharing their knowledge with others. We will serve the industry as a nonprofit organization.

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In the wake of pandemics and travel bans, visitors still turned out for the annual exhibition.

Heading into IPC Apex Expo the first week of February, I wasn’t sure what to expect. The overall market appears to be slowing somewhat. Many EMS companies have reported lower sales for the past quarter. US presidential elections often seem to dampen electronics orders, at least until November, even though a review of the overall GDP disputes any such letup. And fears of the coronavirus in China have clearly spooked the industry, as some firms have reduced or banned employee travel for the time being.

But once the show started, many of those concerns abated. Floor traffic was up and down through the first two days, before grinding to a near halt per usual on the third and final day of the show. Exhibitors took note, reporting mixed reviews of the attendance. But when it was busy, it was really busy. It’s hard to say whether the postponement of overseas shows such as Nepcon China and the International Electronic Circuits (Shanghai) Exhibition (better known as the CPCA Show) boosted attendance an ocean away in San Diego, but it probably didn’t hurt. (On Mar. 2, IPC reported 4,211 visitors attended the show, down 20% from a year ago.)

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ADAS auto electronics require zero-defect components.

With construction of a new venue for the 2020 Olympics in Tokyo, the annual Nepcon Japan show was split into two parts this year. There were 67,169 visitors to see more than 2,100 exhibitors. A reported 24,323 people attended the conference presentations. Exhibits included automotive and electronics. The electronics R&D and manufacturing exhibits included IC and sensor packaging, LED and laser diode technology, PCB, SMT, test and measurement, components, devices, and materials. Many highly attended conference sessions focused on 5G, AI, and automotive electronics (FIGURE 1).

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For decades, researchers have considered the potential for cooling hot electronic devices by blowing on them with high-speed air jets.

However, air jet cooling systems are not widely used today. Two of the biggest obstacles that prevent the use of these systems is their complexity and weight. Air jet systems must be made of metal to be able to handle the pressure associated with air jets whose speed can exceed 200 miles per hour. And the air handling system can be complex with many discrete components that manage the air flow and direct the air onto the hot spots where cooling is required.

Now, researchers at the University of Illinois at Urbana-Champaign have demonstrated a new type of air jet cooler that overcomes previous barriers to jet cooling systems. Using additive manufacturing, the researchers created an air jet cooling system in a single component that can direct high-speed air onto multiple electronics hot spots. The researchers manufactured the cooling system from strong polymer materials that can withstand the harsh conditions associated with high-speed air jets.

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