By Ed Sperling
Nvidia is jumping into a slew of non-traditional low-power market with its Tegra 2 chips. Given this is a combination of ARM Cortex-A9 cores and GPUs, it’s an interesting play across a variety of consumer markets than the computer graphics market that Nvidia grew out of. This draws battle lines against a slew of new competitors ranging from Intel (in the non-GPU areas) to Freescale and Texas Instruments. The key differentiators: Speed, price and battery life.

While consumers are very aware of just how much battery life they get, that arguably pales compared to what’s going on in medical and industrial equipment. If your portable medical device runs out of battery it can be life-threatening. And if your industrial control is sitting in a place where you can’t easily replace a battery, it can bring down an entire assembly line until it’s fixed. Analog Devices seems to be very aware of this with its new line of SHARC processors. You’d guess that others can’t be far behind.

You’d probably guess right, too. STMicroelectronics introduced its own low-power motor controls for everything from air-conditioners to washing machines. The company also has come out with evaluation platforms to let potential customers simulate its chips in action.

And if you’re wondering why companies are paying so much attention to LED lighting, check out the specs on a new GE bulb—9 watts for the equivalent of a 40-watt incandescent bulb.  That may explain why many local governments are ripping out the sodium vapor streetlights and replacing them with LEDs.

By Ellen Konieczny

Imagine that you go to your kitchen to get a drink and pass your home’s energy-usage monitor. Due to a recent heat wave, you see that your energy usage is already at what it usually is for the entire month. Yet you’ve still got one week left in your billing cycle. To keep the bill low, you turn your A/C thermostat up a degree and make a mental note to not keep lights on unnecessarily.

The next day, the weather is more comfortable. You log in from work and turn the A/C off completely. Such capabilities are not farfetched, thanks to plans to roll out smart-grid networks across the globe (see Figure 1). In fact, some utility companies have already tested these technologies. For such two-way communications to be realized on a grand scale, however, the infrastructure, smart meters, and millions of wireless devices involved will need to consume minimal power.

Fig. 1: The various aspects of the smart grid and how they will be connected. (Courtesy of Ember Corp.)

Emmanuel Sambuis, general manager for the metering business at Texas Instruments, says water and gas meters now require 20-year operation from the same battery. In some devices, the requirements are now as much as 25 to 30 years—particularly in areas where batteries are particularly difficult to access or where there are so many devices that changing out batteries can become expensive. In some extreme cases, companies have been developing energy-scavenging solutions that require no batteries at all.

What’s changing, however, is the addition of low-power communications technology inside of even home-area-network products, such as in-home displays and intelligent thermostats. Generally, such low-power communications are RF-based. In the case of power-line communications, regulations also apply and force the energy consumption to be minimal. To raise energy efficiency in e-metering applications, TI has developed an SoC microcontroller that integrates all metering functionality onto a single chip, with ultra-low-power operation so that only simple voltage regulation is required for a complete solution. The MCU provides direct device operation from a 3V supply with the CPU and ESP active at only 2.5 mA. During a power outage, the device can operate in standby mode at 1.1 µA with the real-time clock function active.

It is essential to keep in mind that smart-grid devices will most likely be asleep for the majority of the time. “The biggest challenge is in enabling the battery-operated devices to not be awake for long periods as well as for them to be able to join the network, acquire and process any data as quickly and efficiently as possible, and go back to sleep, said Skip Ashton, senior vice president of engineering at Ember Corp. “Designing technology–radio, processor, and networking software–which enables devices to do that reliably and securely is the crux. A user of a battery-operated device expects instant operation and control when they are using it but long battery life when they are not. This type of ‘instant-on’ capability requires coordination of the radio as well as the software controlling the devices.”

Thankfully, standards bodies like the ZigBee Alliance (www.zigbee.org) include low-power operation as a critical goal as they develop their protocols. For suppliers implementing the protocols and hardware, however, Ashton emphasizes it is important to view the technology offering as a “system” that includes hardware and software. “A tightly integrated platform, which has been developed from the ground up to work together to deliver excellent performance, efficiency in code size, and processing of security and application data, lends itself to better resolve the challenge of minimizing power consumption and extending battery life. Although the standards can prescribe a certain level of behavior, different suppliers can innovate within the standard to improve performance,” Ashton says.

In addition to running IEEE 802.15.4/ZigBee wireless, for example, the MeshConnect modules and integrated circuits (ICs) from California Eastern Laboratories promise to get good range out of a very low-powered device (Fig. 2). According to David Cohen, director of marketing, and Rich Howell, director of business development, the MeshConnect modules and ICs put out +7 dBm power out native (i.e., without using an external power amplifier). The MeshConnect technology delivers standby mode at less than 0.3 µA.

Figure 2: With sleep-mode power consumption below 1 µA, the MeshConnect Extended Range Module offers extended battery life

Although such products are impressive innovations on their own, they are only part of a bigger picture. A successful smart grid will require close collaboration between providers of communication devices (RF transceivers and processors, for example), providers of communication software, and designers of communication systems. In addition, success will largely depend on advances in signal processing.

“Smart-grid technology developers look to advanced digital and analog signal-processing technology to power next-generation energy infrastructure,” said Ronn Kliger, energy group director at Analog Devices. “By leveraging ICs optimized for a range of smart-grid applications—from energy-metering solutions to dynamic, grid-integrated management and communication systems—developers are able to design intelligent systems that promote energy efficiency and management flexibility.”

Along with energy-metering ICs, the firm offers RF, power-line carrier communication, power management, and digital signal processing in support of smart-grid applications.

Measurement capabilities also will need to be fine-tuned, as standby or “vampire” power poses a clear threat to the smart grid’s low-power-consumption efforts. Standby power results from electronic devices that are plugged into wall sockets, such as TVs, DVD players, cell phones, and answering machines. Whether they are on or off, they consume power 24 hours a day. It is difficult to accurately measure the power that they actually use, however, which is why they must be accounted for in the smart grid. A number of companies have developed ways to measure even the smallest amounts of energy usage. For example, Teridian claims to provide accuracy of +/-0.5% over a 2000:1 dynamic range.

Of course, the most frightening specter haunting power consumption in smart-grid devices may be standby current. This issue becomes especially critical for the finest silicon technology nodes, where transistor leakage current starts to dominate. Leakage power already poses a significant problem at advanced process nodes, and the problem increases with density at advanced nodes. The dynamic power dissipation arising from high-frequency switching of the tens of millions of transistors directly impacts aspects like battery life, packaging and cooling costs, form factor, and reliability.

All of the major EDA companies are now advising SoC developers to consider low power as part of the architecture rather than something implemented later in the flow, and entire flows are becoming power-aware and power optimized. That goes for the process as well as the components. Third-party IP vendors such as Virage Logic, ARM and Synopsys are now standardized on low power versions rather than splitting their product lines between IP geared for low power and performance, and even in the FPGA space, where concern for power was either an afterthought or non-issue, all of the major vendors are now offering lower-power solutions. Actel has even developed chips that rival the power consumption of some of the most advanced ASICs.

By Cheryl Ajluni

It wasn’t all that long ago that voice communication via a traditional landline was the norm. At the time, consumers would have been hard pressed to imagine a world in which anytime, anywhere communication (voice and data) with a device no bigger than the human hand was possible.

Many of those same consumers might today find it hard to conceive of a world in which their mobile phones are powered by the jacket they are wearing, but that too—like the mobile phone—may one day become a commercial reality. Given the ongoing research and developments in this area, that reality may be closer than many people think.

One technology hoping to give life to this vision is energy harvesting—a process by which energy is derived from an external ambient source (e.g., kinetic energy, RF, solar power, thermal energy, or vibration and wind energy), captured and then stored. Energy harvesting devices convert the ambient energy into electrical energy. In a wearable electronics application, for example, power captured from an ambient energy source is converted to electrical energy and stored in a device like a battery or a capacitor. The stored power can then travel through a microprocessor and be subsequently transmitted, usually wirelessly. Energy harvesters generally provide only small amounts of power (e.g., just a few milliwatts), dependent in part on their design and size, and are therefore considered suitable for powering low-energy electronics or small, autonomous devices like those used in wearable electronics and wireless sensor networks.

Energy harvesting technology has a number of critical benefits, namely cost and extended battery life. Ambient energy, the fuel that drives energy harvesters, is present in large quantities in nature and is, for all practical purposes, free. By harvesting or “scavenging” small amounts of power from these sources, the battery life of existing devices can be extended. But energy harvesting also has the potential to enable a new class of battery-free devices that can be powered indefinitely and deployed with minimal to no maintenance.

The problem with energy harvesting is that it requires ready availability of a potentially unreliable power source. In very simplistic terms: what happens if the energy harvester relies on wind and the wind dies down? Or what if it relies on sun and it’s a cloudy day? One possible solution to this dilemma is RF energy harvesting, which is now being eyed by the wireless communications industry as a viable power source for wireless electronic devices. RF energy is, after all, available everywhere—particularly in metropolitan areas. Moreover, RF energy harvesting can be coupled with a dedicated radio transmitter to provide remote power that is controllable through continuous, scheduled or on-demand power transmissions.

Energy harvesting on the cusp
RF energy harvesting devices have the potential to one day be used to power or recharge mobile phones, mobile computers, and even radio communications equipment using ambient radio waves emitted from WiFi, phone towers, television signals, and other sources. But is the technology really ready for prime time? In truth, the commercialization of this technology is likely a number of years away, but there is definitive progress being made. One company actively exploring that very possibility is the Finnish mobile phone maker Nokia. At the Nokia Research Center (NRC), researchers are investigating the concept of an energy harvesting handset—one that uses energy harvesting technology to recharge itself using only ambient radio waves. Energy harvesting would need to account for roughly 20 mW+ of power to keep a handset in standby mode indefinitely. Recharging the handset’s battery would require approximately 50 mW of power.

Intel also is actively researching the harvesting of free energy sources like the sun, kinetic energy and RF energy. In fact, earlier this year it conducted an experiment in which it harvested ambient RF energy using a television antenna pointed at a local television station tower. It harvested enough energy to actually power a wall-mounted, household weather station with an LCD screen, effectively proving that wireless power over a distance and battery-free operation is possible.

For the experiment, Intel employed an ambient RF harvesting technique similar to technology typically employed with off-the-shelf RFID tags. Here, unpowered ID tags are powered wirelessly from a tag reader that supplies just enough power to the ID tag so that it can read the information it contains. With RFID tags, the ID tag and tag reader must be in close proximity to one another. With Intel’s RF harvesting technique, the weather station was powered by a television station antenna located some 4 km away. The television antenna was connected to a 4-stage charge pump power harvesting circuit featuring the same design as that found in an RFID tag. Across an 8-KOhm load, researchers measured 0.7 V, corresponding to 60 microwatts of power harvested. That was enough to drive a thermometer/hygrometer and its LCD display, which is normally powered by a 1.5-volt AAA battery.

Key enablers
One factor playing a key role in moving RF energy harvesting forward is the advent of ultra-low power electronics for the power-conscious wireless communications industry. In the past, engineers and researchers working on energy harvesting technologies were hard-pressed to make their energy harvester designs work. They simply couldn’t harvest enough power to run a microcontroller. Today though, the power being harvested with energy harvesting devices is on the rise and the power electronic products require is decreasing. The convergence of these two trends is, for the first time, making energy harvesting technology a viable energy source in many markets, and could result in the emergence of a new class of renewable energy applications that essentially run forever—autonomously, remotely and without a battery.

Two companies that are working hard to develop low-power electronics (e.g., DSPs, microcontrollers, RF transceivers, and sensors operating on just μA’s of electrical current) for use in emerging technologies like energy harvesting are Analog Devices and Texas Instruments. ADI, for example, offers an ultra-low-power MEMS (microelectromechanical system) sensor, the ADXL345, which consumes 120 μA in full dynamic range and 25 μA in sleep mode (Figure 1). TI’s MSP430 microcontroller consumes a mere 160 μA/MHz in an active state and 1.5 μA/MHz in standby mode (Figure 2).

Figure 1. Shown here is a functional block diagram of ADXL345—a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16 g.

Figure 2. TI’s MSP430 MCUs are comprised of a 16-bit RISC CPU; modular, memory-mapped analog and digital peripherals; and a flexible clock system combined using a von-Neumann common memory address bus (MAB) and memory data bus (MDB). They are considered the industry’s lowest power solution for 8- to 16-bit battery-powered measurement applications.

Even University researchers have jumped on the bandwagon. Kansas State University, for example, has recently developed a single-chip microtransceiver for use in energy harvesting radio technology destined for future Mars missions as well as other earthly applications like powering radios for remote wireless sensors. The low-power RF chip uses a silicon-on-sapphire CMOS process from Peregrine Semiconductor Corporation (www.peregrine-semi.com) and operates in the 390-450 MHz band with 100mW output. It includes an integrated transmitter and superheterodyne receiver with an off-chip IF filter. To date, University researchers have already produced proof-of-concept hardware for using the single-chip radio in energy harvesting applications.

Conclusion
With the continued drive toward more energy efficient devices—especially when it comes to wireless communications applications—industry is being challenged to identify new means of powering devices. Energy harvesting, and in particular RF energy harvesting, offers one viable solution. While it may be awhile before wireless devices powered through this method make their way to market, progress is being made. Ultra-low power electronic components will play a key role in moving this technology forward. Coupling these components with energy harvesting technology is today allowing applications that were once unthinkable, like a knee brace that generates power from walking. In the years ahead, this technology will likely be leveraged with other alternate energy solutions and things like better power delivery and power management, to create electronic products that are both cheaper and more ecologically friendly.

By Ed Sperling

The semiconductor industry is getting a better reception from the Obama administration than it has in years from previous administrations, which all but ignored warnings about global warming and a destabilizing dependence on foreign oil.

In fact, the new mantra of saving power while improving the quality of life could drive one of the biggest boons in the industry’s 60-year history. Much of that is included in a new report from the American Council for an Energy Efficient Economy, a non-profit group comprised of some of the top companies in the chip industry. The group issued a new report entitled, “Semiconductors are now the driving force behind U.S. energy efficiency gains.” It said the U.S. economy could expand 70% through 2030 and still consume 11% less energy.

That estimate may be conservative, however, particularly once things like energy harvesting and broader power-saving features begin hitting the market.

“We certainly can do things differently to save energy,” said John Perzow, marketing director for the power management group at Analog Devices. “In a wind farm, you can do a lot of monitoring to avoid human intervention with vibration sensors. That lowers the cost. It also means that you don’t have to drive out there and check them, and then drive back.”

He said the same is true with lighter televisions. The new ones use less power, but because they weigh less they also take less energy to ship.

But the biggest gains may come from utilizing some of the same power-saving techniques developed for portable, battery-driven devices inside those with a plug. If a server in a data center is only 15% utilized, for example, parts of it—particularly cores within the processor—can be turned off completely when they’re not being used.

“Those kinds of techniques are definitely getting shared between portable and non-portable systems,” Perzow said. “We talk to our colleagues in the hall.”