News Column

Patent Issued for Adaptive Voltage Adjustment Based on Temperature Value

July 15, 2014

By a News Reporter-Staff News Editor at Journal of Technology -- A patent by the inventor Takayanagi, Toshinari (San Jose, CA), filed on September 5, 2012, was published online on July 1, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8766704 is assigned to Apple Inc. (Cupertino, CA).

The following quote was obtained by the news editors from the background information supplied by the inventors: "This disclosure is directed to electronic circuits, and more particularly, to supply voltage adjustments based on reported temperature values.

"Advances in integrated circuit (IC) technology have increased the number of transistors on a single IC chip. The operating frequencies of some IC chips has also increased. The large number of transistors and increase in operating frequency has resulted in a corresponding increase in power consumption by IC chips. A corresponding increase in thermal output has also accompanied the increase in transistor count and operating frequency.

"Management of power consumption and thermal output has increase in importance with the above-mentioned advances in IC technology. This is particularly true for portable devices that may rely on a battery for at least some of their operation. One manner in which power may be saved is to reduce the operating voltage of an IC. The power consumption by a given IC can be calculated as the square of the operating voltage. Accordingly, reduction of the operating voltage can have a significant impact on power consumption. However, ability to reduce the operating voltage may nevertheless be limited. Circuits within a given IC typically need a certain amount of voltage to operate properly. Furthermore, the operating voltage may include a guard band that is a surplus voltage added to the required voltage. The guard band may allow for factors such as power supply noise, as well as for process, voltage, and temperature variations while ensuring that circuit internal to the IC receive sufficient voltage for proper operation."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "Various embodiments of a method and apparatus for performing adaptive voltage adjustment based on temperature value are disclosed. In one embodiment, and integrated circuit (IC) includes logic circuitry having at least one temperature sensor therein. The IC also includes a power management circuit coupled to receive temperature readings from the temperature sensor. The power management circuit is configured to determine a temperature of the IC based on a temperature reading received from the temperature sensor. The power management circuit may compare the determined temperature to a temperature threshold. If the temperature exceeds a temperature threshold value, the power management circuit may cause the operating voltage to be reduced by an amount equivalent to a voltage guard band.

"In one embodiment, a power management circuit may compare a determined temperature of the IC to a temperature value that is equivalent to the temperature at which a production test of the IC was performed. The production test is also performed at a first voltage. For temperatures below the temperature threshold, the IC may operate at an operating voltage that is a sum of the first voltage and a guard band voltage. The additional guard band voltage may be provided to ensure a sufficient operating voltage by the circuits in that power domain. If the temperature is determined to be above the temperature threshold, then the operating voltage may be reduced by the guard band voltage, effectively removing the guard band. This may be possible since, based on the production test, it is known that the IC may properly function at the first voltage (i.e., without the guard band voltage) at that particular temperature. In some embodiments, an additional temperature guard band may be added to the production test temperature.

"While the discussion above has been directed to an IC as a whole, the method and apparatus embodiments may be applied more particularly to particular power domains in an IC that implement multiple power domains. The other power domains may or may not implement the same methodology, depending on other factors such as their operating requirements.

"Since the power management circuit in one embodiment may base decisions on whether a temperature is above or below the value at which production test occurred (or a threshold based on that temperature), the design of the temperature sensors may be simplified. Embodiments using ring oscillators or various diode-based designs to implement the temperature sensors are possible and contemplated.

"In some embodiments, the methodology may be extended to temperatures other than that at which production test occurred. For example, in one embodiment a power management circuit may compare a temperature value to a threshold that is less than the threshold based on the production test value. If the temperature is greater than the lower threshold value but less than the greater threshold value (upon which production test was based), the operating voltage may be reduced by a portion (but not the full amount) of the guard band. In general, the methodology described herein may take advantage of the fact that at higher temperatures, lower operating voltages may be used in some cases."

URL and more information on this patent, see: Takayanagi, Toshinari. Adaptive Voltage Adjustment Based on Temperature Value. U.S. Patent Number 8766704, filed September 5, 2012, and published online on July 1, 2014. Patent URL:

Keywords for this news article include: Apple Inc., Technology.

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Source: Journal of Technology

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