Microelectromechanical systems (MEMS) and other technologies may represent a paradigm shift as analog chip makers struggle with immediate and long-term challenges (see “Analog Survival Means Learning To Be Adaptable,” p. 17). This is the way Todd Borkowski, marketing manager of the Micromachined Products Division at Analog Devices, characterizes the thinking behind the development of ADI’s MEMS technology, relative to the limitations of electret condenser microphones (ECMs):
“Part-to-part MEMS product tolerances are highly repeatable since MEMS-based microphones are fabricated in a photolithography-defined semiconductor process. As a result, MEMS microphones perform better than ECMs for multi-microphone applications ranging from simple stereo to more complex arrays.”
Borkowski also said that MEMS microphones eliminate the time-consuming practices associated with EMC microphones, such as hand assembly and hand sorting. “Furthermore, the higher reflow temperatures required for lead-free solder do not affect silicon-based MEMS microphone performance, enhancing the end product quality and reliability,” he notes.
Not all these devices are created equal. Comparing the ADI mikes to other MEMS microphones, Borkowski said that ADI’s offer a flat frequency response from 100 Hz to more than 12 kHz. The company’s engineers also “developed a MEMS element capable of withstanding greater than 160-dB sound pressure level and greater than 20-kg shock forces.”
MEMS AND MORE AT NATIONAL • Beyond microphones, National Semiconductor’s Rick Zarr seconded the notion that, looking forward, MEMS will be playing a more important role in analog semiconductors. He said that magnetics and high-dielectric capacitors will migrate onto chips to provide complete systems with passives.
“I’ve been watching the developments in this area and people are experimenting with all kinds of materials that can be built into structures on an integrated-circuit process. These are not necessarily mechanical in nature, but use mechanical structures to create passive elements such as inductors—and fairly good ones too!” he says.
“I think within the next two to five years, you will start to see the first generation of fully integrated solutions on a single die (passives and all). It will allow many of the portablemobile- device (PMD) companies (Apple, Nokia, etc.) to push more functionality into the design or simply reduce the footprint (maybe in thickness, or other dimensions). MEMS will also play a big role in new technologies such as pico-projectors,” he says. “This stuff is just too cool to believe!”
If you’re interested in a visual example of what Zarr is talking about, display consultant Joseph Hallett and I shot a video at last spring’s Society for Information Display Conference, posted at http://electronicdesign.com/shows/SID2008/video/Microvision.html. Newer information is available at Microvision’s own site: www.microvision.com.
Along these lines, Zarr added an interesting note for an editor whose beats cross the analog/power boundary. He says that a chip company such as National might extend its business model to licensing its IP. “Watch for more technologies to reduce power in digital systems and closer partnerships between digital and analog companies,” he says.
“You can see the importance today in reducing the cost of ownership (electric bills) for operators. National has been engaged in the mobile handset space for a long time to reduce power in DSPs or processors—mostly to improve run time,” says Zarr. “Now we’re partnering with digital chip suppliers to help them get the power out of the racks of equipment.”
The Teranetics Tn2022 dual-port 10GBaseT physical-layer (PHY) IC enables switch manufacturers to squeeze as many as 48 RJ-45 ports into a single rack unit, doubling the port density possible with previous 10GBaseT PHYs. According to Teranetics, that works out to new systems that deliver 10 times more bandwidth at barely one-third the cost per gigabit of bandwidth. National’s energy-efficient PowerWise AVS (adaptive voltage scaling) technology supports the Tn2022.
A MEDICAL UPDATE FROM TI • Soon, chip makers will put ultrasound machines right in doctors’ pockets. For example, Texas Instruments’ eight-channel AFE805 front end targets compact ultrasound systems, following up on TI’s AFE58xx family of analog front ends for ultrasound (see the figure). Each channel consists of a low-noise amplifier, voltage-controlled attenuator, programmable-gain amplifier, low-pass filter, and 12-bit analog-to-digital converter (ADC), with control logic, all in a 15- by 9-mm package.
“New uses of electronic medical devices and emerging economies are driving the need for innovative, portable ultrasound systems. Doctors in remote regions and medical technicians in first-responder situations need a non-invasive tool for accurate, on-site diagnosis. By carrying a system at all times, doctors can also use ultrasound for new application areas,” says Matt Harrison, marketing director for Medical High Reliability Products at TI.
“Semiconductor technology is enabling this huge innovation step by bringing new levels of integration, power efficiency, and noise reduction to create portable, even handheld ultrasound systems,” continues Harrison.
“The demand for smaller, portable ultrasound systems has driven the need for improved underlying technology in semiconductor component integration and resulted in significant improvements in size and power. For example, Analog Devices’ AD9273 eight-channel octal receiver has enabled a power savings of greater than 50% per channel over current systems, and PCB (printed-circuit board) area savings of more than 90% have been achieved,” says Tom O’Dwyer, Healthcare Team technology director at Analog Devices. “The trend of integration has greatly eased the equipment design task.”
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TI AND LOW-POWER WIRELESS • “In 2009, TI will release a new wireless audio technology designed to provide a robust solution for wirelessly transmitting high-quality audio,” says Emmanuel Sambuis, marketing manager for TI’s low-power RF products. “Compared to existing wireless audio solutions, this technology will provide excellent performance in terms of robustness, audio quality, audio latency, and flexibility.”
While Bluetooth Low Energy (BTLE) is an emerging technology, it’s not among the innovations TI plans to consider for this novel solution. “The TI RF business group includes all low-power wireless developments/technologies, such as ZigBee, proprietary, RF4CE (radio frequency for consumer electronics), BT (Bluetooth), BTLE, etc. The wireless audio technology we mentioned is not BLTE,” says Sambuis.
SYSTEM-IN-PACKAGE AT LINEAR • Linear Technology has a strong tradition of standing by its roots and honing its amplifiers and data converters— while making those basic building blocks less sensitive to layout issues (to the extent that the laws of physics allow). Those trends came together in a natural way last year.
“SiP (system in package) technology is commonly used in consumer applications ranging from USB memory sticks to RF modules in wireless handsets. Recently, Linear applied it in the LTM9001 µModule Receiver Subsystem, which integrates a 16-bit, 130-Msample/s ADC with a fixedgain amplifier, anti-aliasing filter, and bypass capacitance,” says Todd Nelson, manager of Linear’s signal-chain module development.
The placement of supply bypass capacitors represents a simple example. With SiP technology, the internal bypass capacitors can be much closer to the die than in a discrete design, yielding a much smaller “ac footprint.” This ultimately reduces the risk of collecting noise from unintended sources and raises the noise floor. The result is consistent with Linear’s traditional philosophy, but also with new trends that are common across the analog chip industry.
