This first issue of 2008 is a chance to take a fresh look at one's life, job and industry. And with an issue theme of "Test & Measurement," it is only appropriate to try and size up developments in RF/microwave measurement equipment and what to expect from test gear manufacturers in the next few years. "If you can't test it, you can't ship it," is a time-honored adage in this industry, one that emphasizes the importance of maintaining the highest possible measurement capabilities.
In some cases, simply being able to test something is an important first step. With the proliferation of digital buses transporting data at microwave speeds, companies like Intel (www.intel.com) are relying on microwave equipment to characterize their devices and systems. The expansion of high-speed digital communications has forced many digital designers to absorb a quick education on S-parameter measurements and vector network analyzers (VNAs) in order to characterize their devices, circuits, and transmission lines, leaving behind the comfort of their digital storage oscilloscopes (DSOs) and logic analyzers.
In addition to speed, there is the matter of configuration as well in modern testing, with differential or balanced devices and circuits being increasingly used in high-frequency/high-speed networks to ward off the deleterious effects of noise. Balanced circuits can cancel noise, but they introduce an additional set of conductors, turning that test requirement from a two-port VNA to a four-port (or higher) VNA. In fact, with the growing use of differential circuits at RF/microwave analog and digital rates, instrument manufacturers are exploring customer requests for "N-port" VNAs, where N can reach 12 and beyond.
The growth of high-speed communications buses is affecting the way RF/microwave engineers interconnect their test tools. The simplicity of Universal Serial Bus (USB) connections (see p. 78) allows a laptop computer to function as the "intelligence" and display screen for an RF/microwave power meter. Also, local area networks (LANs) are used to connect and control test instruments using LAN Extensions of Instrumentation (LXI) guidelines, with Internet access providing truly remote operation. Many in the industry view the LXI standard (www. lxistandard.org) as the natural successor to the aging General Purpose Interface Bus (GPIB) as a means of remotely connecting and controlling test instruments and automatic-test-equipment (ATE) systems.
Instruments are moving away from single boxes with defined functions to flexible tools capable of software-defined configurations. Whether they are called "synthetic instruments" or "virtual instruments," the idea is the same: to provide as much functionality in the smallest size and for the lowest cost possible.
Jack Browne
Technical Director