The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 24, 2004
Filed:
Apr. 26, 1991
Ronald L. Williams, San Marcos, CA (US);
Alan G. Thiele, San Diego, CA (US);
Raytheon Company, Waltham, MA (US);
Abstract
A secure circuit is protected from reverse engineering by sensing radiation to which the circuit is normally not exposed, but which is present in its analysis. The circuit is modified in response to such radiation so that it is not compromised by subsequent analysis. The secure circuit can be implemented as a volatile memory having a power supply circuit that is interrupted in response to radiation exposure. Alternately, a circuit used to burn out the secure circuit, or to reprogram the circuit in the case of a programmable memory, could be actuated by the radiation exposure. Reprogramming mechanisms include an operational amplifier with its input state controlled by a photodiode, a random access memory cell with inherently photosensitive transistors, and a photosensitive transistor switch connecting a multi-vibrator to a memory address line.