That wonderful RF spectrum may offer functionality and job security.
Recently I was talking to my friend Charley Capers of Trilogy Circuits in Dallas. Charley and I talk regularly on what’s going on in the PCB world and, of course, to stay current on our beloved Dallas Cowboys. (I am writing this the week after they won their first playoff game. If things don’t go well, you may hear some cursing by the time this comes out.) Charley mentioned that Trilogy has carved out a nice niche in RF design. This struck a chord with me because I remember doing some RF and microwave designs back in the 1980s. Then, we talked in terms of 1 GHz. Charley, however, was talking about frequencies in the multiple gigahertz range. This piqued my interest, so I started calling around.
It turns out that while RF may not be considered mainstream right now, it does account for a lot of designs. RFID is one technology that comes to mind, but with the exception of some silicon-based RFIDs, it is considered by most to be a low-tech design. But if you consider all the commercial products that use wireless communications, you’re still talking about a lot of circuit boards. Looking at the top of my desk, there’s a cellphone, the wireless connection to my server, a wireless printer, a Bluetooth headset for the cellphone, and a wireless keyboard and mouse. If I were to inventory my house and office, I’m sure I would find quite a few more wireless applications.
Of course, those applications are all in the 2.5 GHz range or less. Charley was talking about designs in the 10 GHz range and higher. According to my old frequency spectrum chart, “superhigh” or microwave frequencies start around 3 GHz, and “extremely high” frequencies (EHF) start around 30 GHz and go up to around 300. The designs Charley refers to are military applications such as radar, missiles and guidance control systems. But others such as airport x-ray scanners are becoming part of our everyday world and will incorporate frequencies in the RF and microwave spectra.
I also spoke with Dale Hanzelka, a principle applications engineer with Atlanta’s Intercept Technologies. Intercept is an EDA company that specializes in RF and other high-speed designs. Dale agreed there is still some black magic to RF design. A good portion of the layout is shape-based, and many of the physical features have to be “tuned” to that particular design. These parameters are difficult, if not impossible, to define at the schematic level. As a result, many engineers use products like AutoCAD to do the layout. While AutoCAD may get the physical features right, and could still generate Gerber files, there is no intelligence to the data. Some companies even have gone to the extent of developing in-house applications to work with AutoCAD instead of finding a CAD application specifically designed for RF and microwave designs. I asked if that means we’re talking about trial-and-error and iterations of prototypes to get things right. That was the old-school approach, Dale told me. Today, the best process is to do the layout and use modern tools to analyze and simulate the design before going to fabrication.
Dale also talked about applications like hybrid designs that include cavities in the substrate and wirebonding, which start to separate the everyday designers from RF and microwave specialists. As more wireless products become integrated in our lives, being one of those designers who knows as much as possible about RF may be a form of job security. Throughout the coming months, we’ll try to do our part by including some more features and columns on RF and microwave design in the magazine and address them at our conferences.
And just to show how deep into our lives this can go, Dale mentioned that for Christmas his wife received a handheld bar scanner. This handy little gadget sounds interesting. For instance, before throwing away that empty milk carton, she can run the scanner over the barcode and add the information to her shopping list. I suppose the next step would be to beam the grocery list to a Blackberry or other handheld device. That’s the kind of gadget that Uncle Pete could go for.
On another note, I want to remind everyone that Virtual PCB, the only virtual trade show and conference for the PCB industry, takes place March 2-4 at your place. Yes, you can attend the conference and trade show without ever leaving the comfort of your home or office. Registration is free, so go to www.virtual-pcb.com for more information.
Pete Waddell is the design technical editor of PCD&F (pcdandf.com); This email address is being protected from spambots. You need JavaScript enabled to view it..
