Low-power electronics
Low-power electronics are electronics, such as
History
Watches
The earliest attempts to reduce the amount of power required by an electronic device were related to the development of the
The first quartz wristwatches were manufactured in 1967, using analog hands to display the time.[2]
The first digital electronic watch was a Pulsar LED prototype produced in 1970.[3] Digital LED watches were very expensive and out of reach to the common consumer until 1975, when Texas Instruments started to mass-produce LED watches inside a plastic case.
Most watches with LED displays required that the user press a button to see the time displayed for a few seconds because LEDs used so much power that they could not be kept operating continuously. Watches with LED displays were popular for a few years, but soon the LED displays were superseded by
Most electronic watches today use 32.768 KHz
As of 2013, processors specifically designed for wristwatches are the
Mobile computing
When
With lower voltage comes lower overall power consumption, making a system less expensive to run on any existing battery technology and able to function for longer. This is crucially important for portable or mobile systems. The emphasis on battery operation has driven many of the advances in lowering processor voltage because this has a significant effect on battery life. The second major benefit is that with less voltage and therefore less power consumption, there will be less heat produced. Processors that run cooler can be packed into systems more tightly and will last longer. The third major benefit is that a processor running cooler on less power can be made to run faster. Lowering the voltage has been one of the key factors in allowing the clock rate of processors to go higher and higher. [5]
Electronics
Computing elements
The density and speed of integrated-circuit computing elements has increased exponentially for several decades, following a trend described by
The overall
An integrated-circuit chip contains many capacitive loads, formed both intentionally (as with gate-to-channel capacitance) and unintentionally (between conductors which are near each other but not electrically connected). Changing the state of the circuit causes a change in the voltage across these parasitic capacitances, which involves a change in the amount of stored energy. As the capacitive loads are charged and discharged through resistive devices, an amount of energy comparable to that stored in the capacitor is dissipated as heat:
The effect of heat dissipation on state change is to limit the amount of computation that may be performed within a given power budget. While device shrinkage can reduce some parasitic capacitances, the number of devices on an integrated circuit chip has increased more than enough to compensate for reduced capacitance in each individual device. Some circuits –
As circuit dimensions shrink,
Reducing power loss
Loss from
Another method that is used to reduce power consumption is power gating:[7] the use of sleep transistors to disable entire blocks when not in use. Systems that are dormant for long periods of time and "wake up" to perform a periodic activity are often in an isolated location monitoring an activity. These systems are generally battery- or solar-powered and hence, reducing power consumption is a key design issue for these systems. By shutting down a functional but leaky block until it is used, leakage current can be reduced significantly. For some embedded systems that only function for short periods at a time, this can dramatically reduce power consumption.
Two other approaches also exist to lower the power overhead of state changes. One is to reduce the operating voltage of the circuit, as in a
The second approach is to attempt to provide charge to the capacitive loads through paths that are not primarily resistive. This is the principle behind adiabatic circuits. The charge is supplied either from a variable-voltage inductive power supply or by other elements in a reversible-logic circuit. In both cases, the charge transfer must be primarily regulated by the non-resistive load. As a practical rule of thumb, this means the change rate of a signal must be slower than that dictated by the RC time constant of the circuit being driven. In other words, the price of reduced power consumption per unit computation is a reduced absolute speed of computation. In practice, although adiabatic circuits have been built, it has been difficult for them to reduce computation power substantially in practical circuits.
Finally, there are several techniques for reducing the number of state changes associated with a given computation. For clocked-logic circuits, the
Wireless communication elements
There are a variety of techniques for reducing the amount of battery power required for a desired wireless communication goodput.[8] Some wireless mesh networks use "smart" low power broadcasting techniques that reduce the battery power required to transmit. This can be achieved by using power aware protocols and joint power control systems.
Costs
In 2007, about 10% of the average IT budget was spent on energy, and energy costs for IT were expected to rise to 50% by 2010.[9]
The weight and cost of power supply and cooling systems generally depends on the maximum possible power that could be used at any one time. There are two ways to prevent a system from being permanently damaged by excessive heat. Most desktop computers design power and cooling systems around the worst-case
Examples
- Transmeta
- Acorn RISC Machine(ARM)
- AMULET microprocessor
- Microchip nanoWatt XLP PIC microcontrollers
- Texas Instruments MSP430 microcontrollers
- Energy Micro/Silicon Labs EFM32 microcontrollers
- STMicroelectronics STM32 microcontrollers
- Atmel/Microchip SAM L microcontrollers
- IoT Pixel[10]
See also
- Processor power dissipation
- Common Power Format
- Data organization for low power
- IT energy management
- Performance per watt
- Power management
- Green computing
- Dynamic frequency scaling
- Overclocking
- Underclocking
- Dynamic voltage scaling
- Operand isolation
- Glitch removal
- Autonomous peripheral operation
References
- ^ "Intel Processor Letter Meanings [Simple Guide]". 2020-04-20.
- ^ a b Eric A. Vittoz. "The Electronic Watch and Low-Power Circuits". 2008.
- ^ "All in Good Time: HILCO EC director donates prototype of world's first working digital watch to Smithsonian". Texas Co-op Power. Feb 2012. Retrieved 2012-07-21.
- ^ U.S. patent 4,096,550: W. Boller, M. Donati, J. Fingerle, P. Wild, Illuminating Arrangement for a Field-Effect Liquid-Crystal Display as well as Fabrication and Application of the Illuminating Arrangement, filed 15 October 1976.
- ^ Microprocessor Types and Specifications, by Scott Mueller and Mark Edward Soper, 2001
- ^ a b Paul DeMone. "The Incredible Shrinking CPU: Peril of Proliferating Power". 2004. [1]
- ^ K. Roy, et al., "Leakage current mechanisms and leakage reduction techniques in deep-submicrometer CMOS circuits", Proceedings of the IEEE, 2003. [2]
- ^ "How to use optional wireless power-save protocols to dramatically reduce power consumption" by Bill McFarland 2008.
- ^
King, Rachael (2007-05-14). "Averting the IT Energy Crunch". Businessweek. Archived from the original on 2013-01-05.
Energy costs, now about 10% of the average IT budget, could rise to 50% ... by 2010.
- ^ Brad Graves (2021-08-15). "Wiliot Series C Totals $200M". San Diego Business Journal. Retrieved 2022-07-08.
Further reading
- Gaudet, Vincent C. (2014-04-01) [2013-09-25]. "Chapter 4.1. Low-Power Design Techniques for State-of-the-Art CMOS Technologies". In (455 pages)
External links
- "High-level design synthesis of a low power, VLIW processor for the IS-54 VSELP Speech Encoder" by Russell Henning and Chaitali Chakrabarti (NB. Implies that, in general, if the algorithm to run is known, hardware designed to specifically run that algorithm will use less power than general-purpose hardware running that algorithm at the same speed.)
- CRISP: A Scalable VLIW Processor for Low Power Multimedia Systems by Francisco Barat 2005
- A Loop Accelerator for Low Power Embedded VLIW Processors by Binu Mathew and Al Davis
- Ultra-Low Power Design by Jack Ganssle
- K. Roy and S. Prasad, Low-Power CMOS VLSI Circuit Design, John Wiley & Sons, Inc., ISBN 0-471-11488-X, 2000, 359 pages.
- K-S. Yeo and K. Roy, Low-Voltage Low-Power VLSI Subsystems, McGraw-Hill 2004, ISBN 0-07-143786-X, 294 pages.