Electronic Design

High-Speed Serial Data And RF Wireless Dominate Today's T&M

Two key areas of electronics are driving the development of new test and measurement (T&M) instruments—high-speed serial buses and wireless test. Both require very high-frequency capability as well as the ability to support the many standards that are being developed.

There is a movement in digital design, from parallel bus structures to serial buses at microwave frequencies, with the growing set of T&M applications aimed at the protocol layers in communication systems. Due to the finite propagation skew of trace lengths on a printed-circuit board (PCB), digital bus design must change from a parallel structure to a serial structure with embedded clocks.

This has a wide set of implications as digital design enters the microwave range. Jitter replaces setup-and-hold times as the most critical timing parameter of digital systems, with equivalent measurement needs. PCB traces are microwave transmission lines, requiring S-parameter measurements and simulations that are common in the RF domain. These trends have large T&M implications.

On the protocol side, there’s more and more value added to network elements and cell phones in the communication protocol layers of these devices. This will be even more so as the network and devices transition from the circuit-switched world to the packet-switched world. Since half of all T&M focuses on the communications industry, this is an important test trend.

3GPP Long Term Evolution (LTE) and WiMAX are competing trend examples in the wireless communications market. They share common ground with regard to technology contributions from multiple-input/multiple-output (MIMO) and orthogonal frequency-division multiple access (OFDMA).

MIMO, a capacity-enhancing, multi-antenna technology that’s an important component of both Mobile WiMAX and LTE, improves spectral efficiency by allowing more bits/hertz to be transmitted in a given bandwidth. OFDMA, on the other hand, employs the orthogonal frequency-division multiplexing (OFDM) modulation scheme in an innovative way so RF spectrum can be allocated more effectively to more users.

In both cases, the addition of MIMO and OFDMA functionality to the LTE and WiMAX standards results in complex, demanding signals that must be not only accurately created, but also rigorously analyzed. WiMAX and LTE, though differing in their current development and deployment cycles, are demanding rapid and accurate test solutions to meet their global market windows for wireless.

Femtocells can be seen as home basestations, like a Wi-Fi basestation, which connect to a broadband Internet service. As an alternative for hotspots for Wi-Fi, femtocells can be hotspots for 3G mobile phones.

In many ways, femtocells can be considered lower-power versions of basestations, and they could be developed the same way as a basestation for the physical layer or the RF portion. The challenge for femtocells is all about their ability to manage the network and interface to the thousands of cells that could be deployed while dealing with other test challenges like verifying location, synchronization, and security.

Chip counts are decreasing as the industry moves toward its goals, which aren’t necessarily achieved yet, of delivering a single-chip radio that will conserve space and power consumption. This makes test points and test modes critical. Designers no longer always have signals readily available in the form needed to test.

Asia will continue to fuel much of the anticipated growth in the electronic manufacturing services industry with increasing usage of high-speed differential signaling with shrinking components and rising node counts. The key challenge for electronic manufacturing test (EMT) will be figuring out how to meet both business and technology demands that can help manufacturers gain faster and better test access and defects coverage, while at the same time providing better return on invested capital for the customer.

Although these are just a few of the many challenging test trends facing the electronics industry today, it is an exciting time to create and deliver test. The test solutions’ requirements are often multiple years ahead of actual market delivery, and there is a constantly evolving set of standards driving each area of interest, as new and better technologies are being discovered in the electronics industry.

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