Tag Archives: low power

Researchers Develop Long Range Backscatter Sensors That Consume Almost No Power

Researchers at the University of Washington developed a new backscatter sensors that can operate over long ranges with very little power. The researchers demonstrated for the first time that the device runs on almost zero power and can transmit data across distances of up to 2.8 kilometers.

The long-range backscatter system developed by UW researchers
The long-range backscatter system developed by UW researchers

Backscatter communication works by emitting a radio signal and then monitoring the reflections of that signal from sensors. As the transmitter generates the signal, the sensors themselves require very little power. But this kind of system badly suffers from noise. Noise can be added anywhere – on the transmitter side, on the channel or on the sensor array. The key to solving this problem is a new type of signal modulation called chirp spread spectrum.

By using the chirp spread spectrum modulation technique, the team was able to transmit data up to 2.8 kilometers while the sensors themselves consumed only a few microwatts of power. Such extremely low power consumption lets them run by harvested ambient energy and very small printed batteries. The cost is surprisingly cheap too. The sensors would cost just 10 to 20 cents per unit if bulk purchased.

Today’s flexible electronics and other sensors need to operate with very low power typically can’t communicate with other devices more than a few feet or meters away. By contrast, the University of Washinton’s long-range backscatter system achieved pretty strong coverage throughout a 4800-square-foot house, an office area including 41 rooms, and a one-acre vegetable farm at extremely low power and low cost.

Shyam Gollakota, the lead faculty and associate professor in the Paul G. Allen School of Computer Science & Engineering, said,

Until now, devices that can communicate over long distances have consumed a lot of power. The tradeoff in a low-power device that consumes microwatts of power is that its communication range is short. Now we’ve shown that we can offer both, which will be pretty game-changing for a lot of different industries and applications.

These low-power sensors have endless potential applications. They can be used for everything from wearable health monitors to scientific data collection devices. Though there are no confirmed products yet, the team has created few prototypes in the form of flexible sensors worn on the skin, smart contact lenses, and more.

SST26WF064C – Low-voltage 64-Megabit SuperFlash® Memory Device From Microchip

Microchip introduced a new 64Mbit Serial Quad I/O memory device—SST26WF064C with proprietary SuperFlash® technology. The SST26WF064C writes with a single power supply of 1.65-1.95V and significantly lower power consumption. This makes it ideal for wireless, mobile, and battery-powered applications.

Microchip SST26WF064C Flash Memory Chip
Microchip SST26WF064C Flash Memory Chip

This 64Mbit memory device also features DTR or Dual Transfer Rate technology. DTR lets the user access data of the chip on both rising and falling edges of the clock, reducing overall data access time and power consumption significantly. The SST26WF064C utilizes a 4-bit multiplexed I/O serial interface to boost performance while maintaining the tiny form factor of standard serial flash devices.

Microchip’s high-performance CMOS SuperFlash technology provides the fastest chip erase time, consequently, reduces overall power consumption. It also improves performance and reliability of the memory chip. The SST26WF064C’s typical chip-erase time is 35-50 milliseconds, where other chips take nearly 30 seconds to be completely erased.

This chip combines a hardware controlled RESET function which is not present in common flash chips available in the market due to their limited pin count. In SST26WF064C, the user can program the HOLD pin to use for the RESET function. This feature lets the host microcontroller to reset the chip by sending a pulse to it.

SST26WF064C supports full command-set compatibility with traditional Serial Peripheral Interface (SPI) protocol. Operating at frequencies reaching 104 MHz, the SST26WF064C enables minimum latency execute-in-place (XIP) capability without the need for code shadowing on a SRAM. To learn about code shadowing, read this article.

The key features of the SST26WF064C are:

  • Single Voltage Read and Write Operations – 1.65-1.95V
  • Serial Interface Architecture
  • High-Speed Clock Frequency (104 MHz max.)
  • Burst Modes
  • Superior Reliability
  • Low Power Consumption
  • Fast Erase Time
  • Flexible Erase Capability
  • Suspend Program or Erase operation to access another block/sector
  • Software and Hardware Reset mode
  • Software Protection
  • Security ID
  • One-Time Programmable (OTP) 2KByte Secure ID
  • 64 bit unique, factory pre-programmed identifier
  • User-programmable area

To learn more about this memory chip or to purchase some, visit http://www.microchip.com/wwwproducts/en/SST26WF064C.

Renesas Electronics Achieves Lowest Embedded SRAM Power of 13.7 nW/Mbit

Renesas Electronics Corporation announced the successful development of a new low-power SRAM circuit technology that achieves a record ultra-low power consumption of 13.7 nW/Mbit in standby mode. The prototype SRAM also achieves a high-speed readout time of 1.8 ns during active operation. Renesas Electronics applied its 65nm node silicon on thin buried oxide (SOTB) process to develop this record-creating SRAM prototype.

Renesas Embedded SRAM prototype with SOTB Structure
Renesas Embedded SRAM prototype with SOTB Structure

This new low-power SRAM circuit technology can be embedded in application specific standard products (ASSPs) for Internet of Things (IoT), home electronics, and healthcare applications. The fast growth of IoT is requiring all the devices be connected to a wireless network all the time. Hence, products must consume less power to prolong battery life. With this new technology applied, much longer battery life can be achieved enabling maintenance-free applications.

One essential part of the development of IoT applications is the miniaturization of end products. This can be achieved by lowering battery capacity requirement of ASSPs. As an effort to reduce the power consumption in ASSPs for the IoT, there is a technique in which the application is operated in the standby mode and only goes to the active mode when data processing is required.

Now, the conventional way of saving power is to store all important data to an internal/external non-volatile memory and cut off the power supply to the circuit. If the wait time is long enough, this method is effective. But in most of the cases, the device has to switch between standby mode and active mode very quickly causing data-saving and restarting process extremely inefficient. There are even cases where, inversely, this increases power consumption.

In contrary to above, the new technology by Renesas Electronics uses a method where power consumption in standby mode is reduced a lot enabling switching operation to be performed frequently without leading to increased power consumption. Hence, it’s no more required to save data to non-volatile memory. This improves the efficiency further.

The low-power embedded SRAM which is fabricated using the 65 nm SOTB process, achieves both the low standby mode power consumption and increased operating speed.  Such features were difficult to achieve with the continuing progress of the semiconductor process miniaturization.  Renesas plans to support both energy harvesting operation and development of maintenance free IoT applications that do not require battery replacement by enabling ASSPs that adopt the embedded SRAM with SOTB structure.

To learn about all the complex technical information which is not covered in the scope of this article, visit the press release page of Renesas Electronics.

Ultralow Power Transistors Function for Years Without Batteries

Researchers at Cambridge University have just achieved a spectacular breakthrough in electronics design. They have developed new ultralow power transistors that could function for months or even years without a battery. These transistors look for energy from the environment around, thus reducing the amount of power used.

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Dr Sungsik Lee, one of the researchers at the Department of Engineering says, “if we were to draw energy from a typical AA battery based on this design, it would last for a billion years.” The new design could be produced in low temperatures and they are versatile enough to be printed on materials like glass, paper, and plastic.

Basically, transistors are semiconductor devices that function like a faucet. Turn a transistor on and the electricity flows,  turn it off and the flow stops. When a transistor is off however, some electric current could still flow through, just like a leaky faucet. This current, which is called a near-off-state, was exploited by the engineers to power the new transistors.

power-consumption

schematicThe researchers developed a thin-film transistor (TFT) from In-Ga-Zn-O (indium-gallium-zinc-oxide) thin films. To make the material less conductive, the films were fabricated to avoid oxygen vacancies. Eventually, they achieved a new design that operates in near the OFF state at low supply voltages (<1 volt) and ultralow power (<1 nanowatt).

The transistor’s design also utilizes a ‘non-desirable’ characteristic, namely the ‘Schottky barrier’ to create smaller transistors. Transistors today cannot be manufactured into smaller sizes since the smaller a transistor gets, the more its electrodes influence each other, causing a non-functioning transistor.The use of the Schottky barrier in the new design creates seal between the electrodes that make them work independently from each other.

“We’re challenging conventional perception of how a transistor should be,” said Professor Arokia Nathan of Cambridge’s Department of Engineering, the paper’s co-author. “We’ve found that these Schottky barriers, which most engineers try to avoid, actually have the ideal characteristics for the type of ultralow power applications we’re looking at, such as wearable or implantable electronics for health monitoring.”

According to Arokia Nathan of Cambridge’s Department of Engineering, the second author of the paper, this new design can see use in various sensor interfaces and wearable devices that require only a low amount of power to run. Professor Gehan Amaratunga, Head of the Electronics, Power and Energy Conversion Group at Cambridge’s Engineering Department sees its use in more autonomous electronics that can harness energy from their environments similar to a bacteria.

As electronic devices become more compact and powerful, conventional methods for manufacturing electrical components simply won’t do. This unconventional way will not only consume minimum power but it also will open up new avenues for system design for the Internet of Things and ultralow power applications.

This research was introduced as a research paper in Science magazine on October 2016. More details are available here  “Subthreshold Schottky-barrier thin-film transistors with ultralow power and high intrinsic gain”.

Whisper Trigger – An Ultra-low Power Voice Detector

For long period of time, we were using our muscles and bodies to control various machines. However, with the growth of technology, things became much easier. We moved to the use of keypads and buttons to get jobs done. Today, touchscreens have appeared and made everything very simple to use. But we did not get enough, and the near future will be for the voice commands.

Using voice commands implies the need to use detection systems and circuits, which must provide high accuracy results, reliable at both near and far distances, not affected by noise, simultaneously sensitive, fast, and also have low power consumption. Power consumption is very important factor nowadays, especially with the application of Internet of Things (IoT) devices which are powered using batteries and have to work for long time.

Most of current solutions for voice recognition use digital signal processors (DSPs) connected with A/D converters and they work in permanent wake mode which make them consume high amounts of  power in case of IoT applications and smartphones.

The conventional Approach
The conventional Approach

Dolphin Integration, a French corporation works on enabling low-power Systems-on-Chip and provides a solution called Whisper Trigger, an ultra-low power voice detector with outstanding performance of detection, enabling wake-up voice acquisition and recognition when needed. In comparison with other devices, this technology reduces power consumption by 80-90%. It consumes only 20 µA, and needs just 1 millisecond to wake up.

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Dolphin Integration provides also another solution for text recognition and detection of keywords, the Microelectromechanical System (MEMS) which should be connected to DSP and circular buffer to perform the process of conversion, decimation and filtering.

dolphin-greenmems-microphone

Source: Elektormagazine

Passive Wi-Fi – Bringing Low Power to Wi-Fi Transmissions

passive_wifi

Bryce Kellogg, Vamsi Talla, Shyam Gollakota, Joshua R. Smith have published an research article discussing Passive Wi-Fi  transmission that consumes 3 – 4 orders of magnitude lower power than existing Wi-Fi chipsets.

Passive Wi-Fi transmissions can be decoded on any Wi-Fi device including routers, mobile phones and tablets. Building on this, we also present a network stack design that enables Passive Wi-Fi transmitters to coexist with other devices in the ISM band, without incurring the power consumption of carrier sense and medium access control operations

Passive Wi-Fi – Bringing Low Power to Wi-Fi Transmissions – [Link]