Electronic digital logic circuitry – Security
Reexamination Certificate
2008-02-07
2009-11-24
Le, Don P (Department: 2819)
Electronic digital logic circuitry
Security
C340S500000
Reexamination Certificate
active
07622944
ABSTRACT:
The present invention provides a method and apparatus for securing an integrated circuit. A pair of conductive security traces are arranged on an integrated circuit. Driver means provide complementary HIGH and LOW voltage levels to a respective first end of each of the conductive security traces. A first switch means temporarily interrupts the driver means and isolates the pair of conductive security traces. A second switch means temporarily connects the first ends of the isolated pair of conductive security traces to each other so that both conductive traces are at the same voltage. The voltage at the first end of one of the security traces at the LOW voltage is then boosted to one-half of the HIGH voltage level (VDD/2) by the HIGH (VDD) voltage level at the first end of the other security trace. First and second comparators are provided, each of which compares voltages on their respective first ends of the pair of conductive security traces with voltages on a respective second end of the pair of conductive security traces. Means are provided for logically combining the output signals of the first and second comparators.
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Atmel Corporation
Le Don P
Schwegman Lundberg & Woessner, P.A.
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