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VARIABLE IC VOLTAGE & CLOCK FOR AUTOMATIC OPTIMIZATION OF POWER, RELIABILITY, & TEMPERATURE

IP.com Disclosure Number: IPCOM000125734D
Publication Date: 2005-Jun-15
Document File: 3 page(s) / 89K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method is disclosed that provides improvement and/or optimization of one or more of power, reliability, and temperature for integrated circuits (ICs). Methods in accordance with the present invention involve running periodic built-in IC tests to determine voltage threshold of reliable operation. Operation voltage may be adjusted to the minimum required to achieve reliable operation. Minimum supply voltage uses minimum power and maximizes longevity. Maximizing longevity may be particularly important in systems, such as implantable medical device, where surgery may be required to replace a power source for an IC.

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VARIABLE IC VOLTAGE & CLOCK FOR AUTOMATIC OPTIMIZATION

OF POWER, RELIABILITY, & TEMPERATURE

           

A method is disclosed that provides improvement and/or optimization of one or more of power, reliability, and temperature for integrated circuits (ICs).  Methods in accordance with the present invention involve running periodic built-in IC tests to determine voltage threshold of reliable operation. Operation voltage may be adjusted to the minimum required to achieve reliable operation. Minimum supply voltage uses minimum power and maximizes longevity. Maximizing longevity may be particularly important in systems, such as implantable medical device, where surgery may be required to replace a power source for an IC.

 Voltage thresholds for reliable IC operation can vary as a function of manufacturing process and individual defects. Typically, optimum supply voltage is calculated at IC design time, but actually varies by lot and/or individual IC.  Existing and future ICs may have a variety of built-in test features that could be utilized to determine reliable operation. Typically, the digital functions of an IC will operate more reliably with a higher supply voltage. However, overall power consumption increases with supply voltage.

            According to one embodiment of the present invention, on a periodic basis, the IC is programmed to a lower “test" supply voltage, and executes a built-in self-test.  If, over a series of many tests, the IC operates without error, supply voltage is reprogrammed to a lower voltage between the former supply voltage and test-supply voltage. If the IC encounters errors during the built-in self-test, then the existing supply voltage is appropriate.  The algorithm for determining reliable operation may be determined at design time based on knowledge of the manufacturing process.

            In a specific example, assume the normal supply voltage is 1.25 Volts. The test-supply voltage may be, for example, 1.22 Volts.  If the device encounters zero errors in 50 tests (for example, 10 test-clock cycles), this implies reliable operation of 1 error in 1015 clock cycles at 1.24 Volts. The new supply voltage may then be programmed to l.24 Volts, and the new test-supply voltage may be set at 1.21 Volts.

            A benefit of the present invention is lower supply voltage and lower power consumption with increased battery longevity. In the event of a defect on an individual IC that is not caught during the manufacturing test, this invention, in certain cases, detects the weakness and avoids unreliable operation by boosting supply voltage.

            Another benefit of the present invention involves manufacturing test cycle shortening by offloading bench tests to the IC’s built-in tests in accordance with the present invention. Yields may potentially increase by utilizing ICs that are otherwise acceptable but require a higher supply.

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