7/28/2019 Basic Design Cycle in Electrical Engineering

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The Basic Design Cycle in Electrical Engineering

Regardless of whether they're designing semiconductors, PCs, fighter jet controls or cell phones, there

are a few commonalities that cut across most engineering disciplines. Engineering in the 21st century is

a desk job, one that relies on brainwork rather than physical tasks like soldering or wrapping wires. In

rare instances, engineers do have to roll up their sleeves and solder parts onto a board, but that's

becoming less common as products become more complex.

Circuit boards now have circuits as tiny as 0.1 mm, about the diameter of a human hair. That's one reason humansdon't solder chips onto them. But rather than physically make the signals, it's more important that today's electricalengineers understand the subtleties of sending very high speed signals through these signals.

Some designers work with transistors to build integrated circuits like microprocessors and digital signal processors.

Millions of these elements are often combined on a single chip. Other engineers link these semiconductors to other

components, resulting in circuit boards that make the magic of cell phones, computers and other electronic gear a

reality. Still others work at larger levels, bringing to fruition computer networks, cell phone infrastructures and other

complex systems that seamlessly combine many different products together.

Some basic designing tasks remain similar across the board. But specific electronic products demand varying designobjectives. For defense and automotive applications, a product's ability to withstand a harsh environment is key. Lowcosts drive consumer applications. For portable equipment, size and battery lifetimes are paramount.

Given these different parameters, electrical engineers ultimately determine how products will perform. An engineermust know how to tailor a product design to meet these varying requirements. Bosses don't expect new graduates tounderstand these nuances, but young electrical engineers need to pick up these traits quickly to become importantplayers on a design team.

Engineering generally starts with conceptualizing, in which the general ideas about a new product are sketched out.

Sometimes the idea springs from one person, but more often, teams of marketing and manufacturing personnel sitdown with engineers to determine what customers want, and what they can efficiently build.

Once the concepts are firm enough, engineers start figuring out the circuitry that will enable a given product toaccomplish the desired tasks at the necessary price and performance points. This is the mainstay of electronicengineering, the primary daily responsibilities of most engineers--turning marketing goals like a product's size andperformance into actual working circuitry.

To do this, team members must figure out the overall approach, often called the architecture. This is the "back of anenvelope" approach often described for young startups, in which someone grabs some scrap paper and startsshowing others how their concept will work.

The architecture is much like a blueprint, in that it shows only the overall plan, not the actual size of a nail or thespeed of an electronic component. Often, the architecture is derived from previous generation products, or it may be

based on a standard such as PC architecture.

Tinker toys

Today, designs are typically completed on PCs or workstations, which are more powerful computers that can handlethe complex drawing and mathematics needed for designs that can have millions of individual elements. Computer-aided engineering and design programs are the common tools of the trade, along with oversized monitors that makeit easier to see the many fine lines in most products. Many engineers say that these CAE and CAD programs make itseem like they're building a product using Tinker Toys.

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But constructing electronic circuits is anything but child's play. There are subtle nuances in the way components fittogether, and a single error in a large system can hinder performance or even cause a complete shutdown.

CAE and CAD programs now accomplish many of the mundane tasks engineers used to have to do themselves,such as routing the signal lines that link components together on a circuit board. In that instance, determining whichcomponents are needed would be the first step. The architecture defines some parameters, but engineers would thenfigure out which parts do the job efficiently. Specifics like speed, power requirements, cost and component availability

are key parameters. Engineers have to understand technical tradeoffs, but they must also be able to anticipatewhether new parts will become available in the time they need, or whether older parts will become obsolete beforetheir creation is produced.

Arranging these components is the next step. Engineers must consider several factors. Chips that generate heatneed to be separated from each other, so that it's easier to cool the system. Electrical noise must also be taken intoaccount. Just as a cell phone or vacuum cleaner might cause static when it's too close to a radio or TV, electronicparts can interfere with other chips' performance if they're too close to a sensitive device.

Once all of the pieces are properly placed, it's time to start checking the function of the overall design. For this,engineers turn to other development tools called simulation and verification programs. Even if the design exists solelyon the computer at this point, simulation programs can anticipate how the virtual circuit will work. They can tell if thedesign actually does the jobs it's designed to do, and how quickly it accomplishes its objectives.

This can be a lengthy process. Engineers run the simulation, then pore over the results to see how the product isperforming. Sometimes, they're looking for bugs that prevent the system from working efficiently. Other times, they'rethinking about ways to improve the design's performance. When they finish one round, they often run anothersimulation, repeating this cycle until the design seems perfect.

Verifying performance

Once tweaks and fine tuning have been done, verification software performs another round of tests. Often, hardwareand software are verified together in this phase. Software is a critical part of any design, and the way hardware andsoftware work together is crucial. During this phase, EEs will work closely with programmers to weed out any glitches.

All these computerized examinations are usually performed before an actual physical prototype is manufactured, asit's far cheaper to spot and fix problems before real hardware is put together. In the semiconductor world, it's not

uncommon for chip designers to iron out most major problems before the first silicon prototypes are produced.

Even though design tools are able to accomplish more and more of the steps in product design, it's still critical thatskilled workers are on hand to interpret the results of these programs, especially as products continue to grow incomplexity.