Wireless Systems Design

On The Wireless Front

Santa Clara, California
California Eastern Laboratories (CEL) recently announced the availability of an uncooled, 1310-nm, directly modulated laser-diode module. Hailing from NEC, it is designed for the 10-G transmission applications in which high-density mounting and power consumption are a concern. In the history of 10-G AlGaInAs uncooled DFB laser diodes, NEC's NX8340 Series claims to be the first one fabricated using Al oxidation-free, all-selective MOVPE without semiconductor etching.

This module should be ideal for the engineers tasked with miniaturizing their designs. It is available in two 17-pin, mini-butterfly packages: the NX8340MD pigtail version for 300-pin transponders and the NX8340ME SC receptacle version for XENPAK, X2, and XPAK transceivers. Both versions are designed to be surface mounted for easy assembly.

NEC reduced the size of these modules by eliminating the temperature-control circuitry. But it didn't compromise the integration. Aside from the laser diode, the modules include a monitor photodiode, thermistor, optical isolator, and a built-in laser-driver IC. Designed for a differential input with 50-Ω impedance, the modules feature pins for controlling and monitoring the laser bias and modulation current.

Available now, the NX8340 Series modules join CEL's growing family of NEC fiber-optic components. For more information, visit www.cel.com.

Santa Clara, California
The new single-chip analog audio subsystem from National Semiconductor Corp. targets mobile phones and other portable applications. It offers designers an easy-to-use structure and three digital interfaces. Integrated onto a single 36-bump micro-SMD package, these interfaces include pulse-code modulation (PCM) for digital voice data; I2S for digital stereo audio from sources such as MP3; and an I2C interface. The I2C digital control interface sets the mode of operation, volume levels, and other functions.

National's LM4930 Boomer audio subsystem contains the following: a stereo I2S DAC; voiceband codec; stereo-headphone amplifier; mono speaker amplifier; microphone pre-amplifier; and a sidetone generator. All of these features come with I2C control, which enables selection from a variety of operating modes. These modes determine which amplifiers are used. They also specify volume control for each amplifier as well as other performance options.

The LM4930 is available now in 36-bump micro-SMD packaging. It is priced at $3.95 in 1000-unit quantities. More information on the LM4930 is available at www.national.com/pf/LM/LM4930.html.

The XE0092 Telephone Interface Module, which also is known as a Data Access Arrangement (DAA), is now hailing from Xecom, Inc. This module contains a complete, solid-state DAA solution in a compact, low-cost, surface-mount design. The device is suitable for voice; audio; dual-tone multiple-frequency (DTMF); and data and fax applications. Its high level of integration provides users with a smaller device footprint, a lower-cost total solution, and a faster time to market for the end product.

The XE0092 incorporates network isolation, a loop-current holding circuit, and a solid-state hook switch. It also houses a ring detector, 2-4 wire converter, and Caller ID pass-through functions. All of these features are necessary for connecting a voice, audio, or data application to the telephone line.

By providing a clear signal path of less than 80 dB of second-harmonic distortion, the XE0092 provides for higher fidelity. Its low distortion permits the reliable support of 56-Kbps data signals, thereby enabling higher signal throughput. The XE0092 has the flexibility to operate at either 3.3 or 5 V. It draws just 10 mA of current while operating at 3.3 V.

Aside from having the features and performance needed to support a wide variety of applications, the XE0092 has the low ownership cost that is required to be economically attractive. That low cost is derived from price along with a compact, surface-mount package and FCC Part 68 compliance. Compliance to Part 68 Rules speeds time to market by reducing design and test requirements. It also minimizes uncertainty in certification. At just 1.20 × 1.00 × 0.3 in., the compact surface-mount package reduces board space and assembly costs.

Because of its general-purpose design, the XE0092 can be used in a wide variety of applications. An example is voice for 911 emergency systems. In addition, it has potential data applications in remote-monitoring applications. Among them are handheld terminals, security systems, and point-of-sale terminals. In the fax sector, security applications exist as well. Audio patch-to-telephone applications are beckoning from the audio sector.

The Xecom XE0092 DAA is available from stock in sample quantities. The unit price is $5.55 in 10,000-piece quantities. To find more details on this device, please visit www.xecom.com.

Fremont, California
The use of an Indium-Gallium-Phosphorous (InGaP) emitter for RF power amplifiers was pioneered by EiC Corp. In 1998, the company also was the first to introduce gain block products. Now, EiC Corp. offers a series of intermediate power amplifiers based on InGaP Heterojunction Bipolar Transistor (HBT) technology. Today, other semiconductor manufacturers are following suit. In fact, InGaP HBT product is actually superceding Aluminum-Gallium-Arsenide (AlGaAs). As they've proven, InGaP/GaAs HBT devices provide better performance and are more reliable than their AlGaAs/GaAs HBT predecessors. Now, EiC Corp. has taken the InGaP HBT capability to the next level with its introduction of the ECPXXX series of power amplifiers.

Using the same process that's applied to its existing lower-power gain blocks, EiC has made 1- and 2-W MMIC RF amplifiers available. The part numbers for these amplifiers are ECP050 (1/2 W), ECP100 (1 W), and ECP200 (2 W). According to the company, its success in exceeding 1-W capability represents a significant milestone for the industry.

The ECP amplifiers offer features like bias select, which enables the designer to operate the amplifier in Class A or AB. To maximize heat dissipation, they confront the issue of thermal considerations and techniques for circuit layout and package mounting. In addition, the MMICs are offered in exceptionally small outline packages like the 4-×-4-mm QFN. Among the other specific characteristics for the ECP200 power amplifier are a single-stage MMIC design with built-in ESD protection, a Vde of up to 7 V, Class A/AB selectivity, and temperature-compensation bias. Power up/down sequencing is available along with partial-input-matching circuitry that has been built on chip. For more information on this series of power amplifiers, go to www.eiccorp.com.

Taipei, Taiwan
Micron Technology, Inc. has recently demonstrated a combination of high-density and high-bandwidth memory in a VIA Technology desktop platform. This dual-channel DDR400 platform showcases 1-GB DIMM modules, which are based on Micron's 512-Mb DDR synchronous-dynamic random-access-memory (SDRAM) components. The system performs at 400 megabits per second per pin (Mbps/pin). It therefore achieves a system bandwidth of 6400 MBps.

This emerging desktop-computing architecture uses dual memory channels. In a dual-channel system, DIMM modules are installed and accessed in two channels. Building systems with two memory channels provides twice the bandwidth of a single channel system. For more information on the company or its recently demonstrated DDR400 platform, go to www.micron.com.

Sunnyvale, California
Recently, Maxim Integrated Products introduced the world's first monolithic RF predistorter ICs. Known as the MAX2009/MAX2010, each of these devices provides AM-AM and AM-PM distortion correction. They succeed by introducing adjustable gain and phase expansion into a power-amplifier (PA) lineup. These expansion characteristics are specifically designed to counteract the gain and phase compression that are exhibited by today's laterally diffused metal-oxide-silicon (LDMOS) power amplifiers.

In a joint study conducted by Maxim and Motorola, the MAX2009/MAX2010 were shown to provide substantial improvements in PA linearity and efficiency. The results described here are representative of a Class AB PA supporting two W-CDMA 3GPP modulated tones with 10 MHz of channel spacing. These basic linearization enhancements are applicable to virtually any signal format that covers the 500-to-1100-MHz (MAX2010) and 1200-to-2500-MHz (MAX2009) bands of operation (cdma2000, GSM/EDGE, iDEN, WLAN, etc.).

The devices offer fully independent controls for both gain and phase expansion. All of these features come in a single package that provides up to a 55% reduction in part count. It boasts a 25X reduction in footprint over comparable discrete solutions. For an input signal with a 10-dB peak-to-average ratio, the AM-AM correction can be set to yield 1 to 6 dB of total gain expansion. Likewise, the AM-PM correction can be modified to provide 4° to 19° of phase expansion. Both expansion curves are precision controlled by making simple adjustments to both the slopes and the gain and phase breakpoints.

With these settings in place, the linearization circuit can be run in a static 'set and forget' mode. Or it can employ a more sophisticated, closed-loop implementation with real-time, software-controlled distortion correction. Hybrid correction modes also are possible. Just use simple lookup tables to compensate for factors like PA temperature drift or PA loading.

The MAX2009/MAX2010 are both available in a 28-pin TQFN-EP (5-×-5-mm) package. Each device is specified for the extended (−40° to +85°C) temperature range. Prices start at $9.95 (1000-up, FOB USA). To find out more, go to www.maxim-ic.com.

Peabody, Massachusetts
TRU Corp. has named Mary S. Bennett its Vice President of Worldwide Marketing & Sales. She replaces Douglas E. Snader, who will now head TRU Consulting Services.

Ms. Bennett joins TRU from Xerox Corp. Among other executive positions, she was Director of North American Operations for Xerox's Multilingual Knowledge Management Solutions business unit. Bennett holds a B.S. degree from the State University of New York at Albany and a Master of Education degree from Bowling Green State University.

In announcing this appointment, TRU CEO Eugene O'Neill, Jr. said, "Because TRU Corporation is planning a significant expansion of our sales and marketing efforts, we conducted a very rigorous search for this critical position. We are delighted to have been able to attract an executive with Mary Bennett's skills and track record." Mr. O'Neill continued, "Doug Snader's move to head our new TRU Consulting division will enable us to have a very smooth and coordinated transition."

For more information, go to www.trucorp.com.

Superconductor Technologies, Inc. (STI) has launched its SuperLink Rx 1900 product. As an integrated cryogenic-receiver front end (CRFE), this product is designed specifically for the PCS wireless market. SuperLink Rx 1900 is STI's first fully integrated system that was designed for outdoor use. The fully weatherized unit includes a SuperLink Rx front end—the company's flagship product—and up to six dual HTS-ready duplexers in an outdoor enclosure. Like their cellular counterparts, PCS carriers can now take full advantage of HTS technology. They can tap into its ability to improve base-station sensitivity and network performance.

The SuperLink Rx 1900 is virtually maintenance free. It features passive thermal management that eliminates the need for cooling fans. The Stirling cooler, which is located at the core of the unit's cryogenic technology, has a mean time between failure (MTBF) of between 800,000 and 1 million hrs.

Like the SuperLink Rx 850, the 1900 is simple to install. It should enable a fast upgrade for a cell site. The product also promises to provide performance without compromise. To eliminate noise from the receiver chain, it delivers both high selectivity and high sensitivity. Competing products, such as conventional filters and tower-mounted amplifiers, can provide only one of these benefits. Plus, they must sacrifice the other benefit in the process.

For field results, look to a recent urban 1xRTT cluster trial. Data speeds increased by more than 50%. This dramatic outcome resulted from the improvement to system sensitivity. The base stations were able to receive signals that were only half as strong as the signals that they could pick up without a SuperLink Rx unit. Among the other network-performance enhancements were greater capacity, fewer coverage gaps both outside and within buildings, and an overall improvement in voice quality.

For more information, go to www.suptech.com.

To simplify radio design for cellular base stations and microwave and satellite links, Linear Technology Corp. now offers two direct-conversion quadrature demodulators. The LT5515 and LT5516 deliver exceptionally high linearity. As a result, they provide a more flexible system design and wide spur-free dynamic range. Compared to discrete solutions, the two direct-conversion devices also claim to significantly reduce costs. On a single chip, they integrate the functionality of a signal splitter, two high-linearity downconverting mixers, a precision local-oscillator quadrature generator (0°/90°), and 260-MHz bandwidth output buffers. Those buffers have single-pole, low-pass filters on each of the outputs.

The LT5515 and LT5516 quadrature demodulators target applications in both cellular infrastructure and microwave and satellite links. In the link applications, they will directly convert a radio-frequency (RF) signal to baseband in-phase (I) and quadrature-phase (Q) components. The devices' matched I and Q channels ensure precise gain and phase matching. As a result, significantly less calibration is required. These direct-conversion receiver ICs eliminate the need for additional intermediate-frequency (IF) stages, local oscillators, and associated filtering.

The LT5515 demodulator operates over an input frequency range of 1.5 to 2.5 GHz. In contrast, the LT5516 demodulator operates with RF input from 0.8 to 1.5 GHz. Both devices are designed for high-linearity applications. Examples include wireless infrastructure of all types, such as base stations for GSM, CDMA, W-CDMA, and fixed wireless communications. They also will target satellite and microwave receivers, high-performance radios, and instrumentation.

The additional characteristics of the LT5515 and LT5516 include a high-input IIP3 of greater than 20 dBm. The devices boast a high-input IIP2 of greater than 50 dBm and an LO drive level of −5 dBm. The I/Q output gain mismatch is less than 0.3 dB. The I/Q output phase mismatch is 1° (typical). Both the LT5515 and the LT5516 quadrature demodulators have a 4.5- to-5.25-V supply-voltage range with shutdown mode (2 µA typical supply).

The LT5515 and LT5516 are offered in 4-×-4-mm QFN packages. In 1000-piece quantities, pricing starts at $6.75 each for the LT5515 and $7.40 each for the LT5516. For more information on these direct-conversion quadrature demodulators, visit www.linear.com.

Alameda, California
In the network-equipment development space, Wind River Systems, Inc. continues to be one of the leading innovators. This past September, the company strengthened its lead by demonstrating one of its most recent improvements at the Intel Developer Forum in San Jose, California.

In response to the constantly changing market needs for Internet Protocol (IP) stack performance, Wind River successfully increased the performance capabilities of its router stack. During the Intel performance test, which used Intel's 1XP425 reference board, the Wind River Platform for Network Equipment (PNE) doubled its improvement over the standard Wind River VxWorks 5.5 network stack. Clearly, the fully integrated, tested, and feature-rich PNE flaunts increased performance. In addition, the PNE works to reduce the risks of developing and delivering products on time and on budget.

In the networking-equipment arena, the market needs for IP stack performance are changing rapidly. Several trends are driving the need for faster IP performance. For example, new access technologies like Very High Data Digital Subscriber Line (VDSL) and Fibre To The Home (FTTH) are driving bandwidth requirements.

Meanwhile, access equipment like DSL, cable, and FTTH modems are requiring higher and higher IP performance. In the wired- and wireless-infrastructure markets, there has been a considerable movement from proprietary circuit-/packet-switched backplanes to standard Ethernet backplanes. Now, manufacturers of these access, wireless, backplane, and other network-infrastructure products are struggling to meet the demand for higher performance. By advancing the performance of its Platform for Network Equipment, Wind River has promised to help them.

According to Dave Fraser, Group Vice President of Products for Wind River, "We are committed to providing our customers with the most progressive, robust, and reliable development solutions. Wind River's Platform NE has revolutionized the way developers can create network equipment."

For more information, visit www.windriver.com.

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