Current Issue

Don’t be afraid of the ground.

Doing special things with a circuit pattern is a hallmark of analog design. All the important signals on the board added together are equal in importance to one net; that net is the ground net. Every active component will have at least one of its pins tied to ground. An RF device could use any number of voltages and will likely want a dedicated power supply for each voltage required. Characteristic impedance relies on a ground plane or two.

Faster digital circuits start to behave like their analog counterparts. The typical routing rules involve fanning out the surface mount pins with short segments and doing the main course of the routing on an innerlayer. An elegant placement could make it possible for the bus of related traces to run entirely on the outer layers.

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Model-based enterprise initiatives often ignore electronics.

Reams of presentations and data support efficiencies gained by digital thread initiatives, but much of the dialogue is driven by mechanical design processes with little regard for the electronics components of a product being developed, deployed and maintained. To review some of these basic concepts, see FIGURE 1, which starts with model-based design as a foundation of a model-based enterprise. This enables a robust digital thread that feeds into Industry 4.0 with smart factory initiatives under a framework of communication and collaboration that is defined as intelligent information management (IIM).

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Simon Fried

Non-planar designs and side-mounted components are next up for 3-D printing.

It is true that even today, so many years after 3-D printing started to garner attention and acclaim, rapid prototyping remains the single most common use for 3-D printers. 3-D printers offer advantages in the form of shorter turnaround times, improved development secrecy and greater design freedoms. But it is also true 3-D printing isn’t going to remain primarily a tool for rapid prototyping much longer.

Those keeping abreast of events in the worlds of design, construction, manufacturing or medicine will be keenly aware of the impact of additive manufacturing in these fields. Certain products have been rapidly affected by the arrival of additive manufacturing. Prime examples are hearing aids and dental aligners. Both markets have been transformed by the adoption of 3-D printing technologies. Additive is now the default manufacturing technology for such products.

Read more: Next-Generation Additive Manufacturing

Lance WangHow to calculate trace length from time delay value for high-speed signals.

To keep a good high-speed signal quality from driver to receiver on a PCB is not an easy task for designers. One of the most challenging issues is managing the propagation delay and relative time delay mismatches. To manage the time delays, we need to know how to calculate trace length from time delay value in order to implement the PCB trace routing accordingly. Let me take you through the process.

Calculating signal speed. According to physics, electromagnetic signals travel in a vacuum or through the air at the same speed as light, which is:

Vc = 3 x 108M/sec = 186,000 miles/sec = 11.8 in/ns

Read more: Managing Time Delays

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