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# Self Adjusting Power Scheme for Optimal Power Reduction

IP.com Disclosure Number: IPCOM000031185D
Original Publication Date: 2004-Sep-16
Included in the Prior Art Database: 2004-Sep-16
Document File: 8 page(s) / 127K

IBM

## Abstract

The maximum power consumption of the device is generally determined by the maximum supply voltage which is inherently set higher than the minimum voltage required for timing and full functional operation. The concept of this invention is to remove as much of the uncertainty through a series of on device structures that can be viewed as monitors which feed a central controller (a state machine would be an example) which in turn tells the voltage to adjust itself up or down as necessary.

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Self Adjusting Power Scheme for Optimal Power Reduction

This invention also takes advantage of the fact that a mechanism exists to control the voltage being supplied to the device via control bits.

The maximum power consumption of the device is generally determined by the maximum supply voltage which is inherently set higher than the minimum voltage required for timing and full functional operation. Some of the difference between these two values cannot be eliminated, but the concept of this invention is to remove as much of the uncertainty through a series of on device structures that can be viewed as monitors which feed a central controller (a state machine would be an example) which in turn tells the voltage to adjust itself up or down as necessary. But the general concept is adjust it down as much as possible so as to reduce the power consumption of the device. Voltage is the number one contributor to both AC and DC power within electronic devices.

As Figure 1 illustrates, there are several components that go into the uncertainty of the voltage at the circuit. Those include AC noise on chip, the DC drop in the package and chip distribution, and the uncertainty of the supply to the device in the first place. Even with Adaptive Power Supply (APS), the supply must be set higher than the minimum required to the package to overcome the uncertainty in voltage level being delivered. This insures that a supply that is set nominally doesn't end up actually being lower than the minimum required. However, some supplies will end up being nominal (which is more that what is required), and others still will end up at the maximum value shown. It is this maximum level that sets that maximum power consumption and is used in power calculations and device measurements under test. By current standards, some fully functional parts must be discarded if they exceed a maximum power limit for the intended application. This reduces the effective yield or raises the price of the product in question.

The central concept of this invention is to collapse the difference between minimum required voltage and the maximum possible voltage supplied to overcome all voltage uncertainties, power delivery losses, and AC noise. In reality, the only voltage that matters in the voltage in the device at the circuit, or the minimum voltage of the device. So the key is to either attempt to measure that voltage as precisely as possible through a number of means on the device itself or to measure items that reflect the voltage or items that reflect the need of the device to continue full operation with some degree of timing margin. Another key is understanding the environment of the device. As shown on Figure 3, most devices operate in a situation where the delivery of the power varies as a function of the current being demanded. Demand on most devices is a statement of how busy the device is in terms of either running nothing (in an idle state where demand is reduced) or r...