I attended the International Microwave Symposium last week in Montreal. Perhaps most of you wouldn’t call it relevant to the mobile space, but it is. True, microwaves are above 1 GHz and most cellular work is above their limits. Still, IMS is a key conference for mobile designers. Most wireless today is microwave, after all.

Microwave initially was associated with radar, transmission lines, and other special wireless applications like satellites and long-distance telephone relays. Today the microwave focus is cellular, wireless local-area networks (WLANs) like Wi-Fi, and other short-range wireless. I didn’t see much associated with handsets at IMS, but the products and technologies for basestations and infrastructure were definitely present.

By The Numbers

The IMS is the annual conference of the IEEE’s Microwave Technology and Techniques (MTT) section, which has been around since 1952. This was the 60^th annual meeting. While only 210 attended that first get-together, attendance in Montreal last week nearly topped 10,000.

This show included an impressive 448 podium papers, 164 interactive forums, 40 workshops, seven short courses, and 351 student papers presenting the latest in microwave technology. There also were 569 exhibitors, and that’s 10% more than last year.

Steve Mollenkopf of Qualcomm discussed the challenges of making 3G/4G chipsets for the mobile data explosion in his plenary keynote. The Qualcomm Snapdragon is one of the leading processor chips for handling the multiple chores of smart phones. Mollenkopf talked about the rapid growth and complexity of the chipsets as they attempt to keep up with the wireless data tsunami and higher data speeds.

By 2015, he said, 50% of the total broadband connections to the Internet will be mobile and wireless. Smart phones and tablets will handle video and other applications yet to come. Qualcomm is working to get greater speeds by making chips with greater bandwidth, more links (MIMO), more antennas, carrier aggregation, and clever network topology. Carriers then will be able to keep up with Moore’s law.

Challenges include the need to handle multiple bands in one phone, creating compatibility and co-existence for multiple radios and antennas, and dealing with thermal problems as chip geometries and phone size continue to decline. Tunable high-Q filters and the front-end “plumbing,” meaning multiple pole switches, are key needs. Also, Mollencompf thinks envelope tracking and digital pre-distortion well help solve thermal issues in power amplifiers (PAs). And, he sees millimeter-wave phones in the future in some form.

Sitting With The Chair

Ke Wu, the general chair of the conference and a professor at Ecole Polytechique Montreal, worked with a crew of more than 65 individuals and IEEE support staff to put together this massive show. He said that there is a deliberate movement to close the gap between the microwave and optical parts of the spectrum, which is the region above 300 GHz and below the far infrared (IR) bands.

Meanwhile, work is being done to close the gap in the so-called terahertz region, which is a large but unused part of the spectrum, at the millimeter-wave and the IR ends. The IEEE’s relatively new publication, Transactions on Terahertz Science and Technology, addresses this challenge. The first issue came out last year, and the second volume was available at the show.

Wu also predicts the development of more multifunction, multi-standard, smart, configurable, and frequency-agile microwave systems on a chip (SoCs). Advances in microwave power devices will continue as well with the growing number of gallium-arsenide (GaAs) and gallium-nitride (GaN) PAs and transistors, which are replacing older devices with ever-higher power levels and improved efficiency.

Furthermore, Wu indicated a movement to resume development in microwave power transmission. It is not going to be the massive wireless power distribution envisioned by Nikola Tesla in the early 20^th century, but it will be effective simply because today we have already developed energy harvesting methods and chips that consume very low power. Look for some future developments in this space.

Vendor Exhibitions

Representatives from Agilent, Aeroflex, Anritsu, National Instruments, Rohde & Schwarz, Noise XT, and Tektronix were on hand to show new products for testing and measuring the new 802.11ac Wi-Fi standard. Most also had test products for Long-Term Evolution (LTE) and even LTE-Advanced.

PAs were emphasized too, and devices with GaN were the stars of the show. GaAs and silicon-germanium and carbon (SiGe:C) are still very much in play at these frequencies, though. GaN is expensive, but prices will tumble as volumes grow, bringing it to more applications. GaN suppliers on hand included RFMD, Cree, TriQuint, Freescale, NXP, Microsemi, Toshiba, and Integra. While GaN is still expensive, it will gradually work its way into most basestations because of its efficiency.

GaAs suppliers like Anadigics, Freescale, and RFMD also showed their devices for handsets and small cells. LDMOS transistors and PAs were well represented by Freescale, Infineon, and Integra. LDMOS rules at frequencies below 2 GHz because of its ruggedness and low cost.

I loved Freescale’s demonstration of microwave ovens made with Chinese partner Midea. They are using LDMOS power transistors to make 150-, 300-, and 600-W microwave ovens operating at the traditional industrial, scientific, medical (ISM) frequency of 2.45 GHz. Maybe the magnetrons used today along with their 4-kV power supplies will finally fade away.

IMS is a great focused RF and microwave show. If you’re an RF engineer, you need to go to at least one of them. It will be in Seattle next year in June.

International Microwave Symposium