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:
Jun. 10, 2008
Filed:
Sep. 28, 2005
Bryan C. Doi, Queen Creek, AZ (US);
Bryan C. Doi, Queen Creek, AZ (US);
ITT Manufacturing Enterprises, Inc., Wilmington, DE (US);
Abstract
A tamper monitor circuit detects voltage, temperature, and/or clock variations that may be associated with a circuit tampering technique, and triggers an appropriate tamper response. The tamper monitor circuit includes a reference oscillator, a detection oscillator, and a comparison circuit. The reference oscillator supplies a reference signal having a reference frequency. The detection oscillator operates at a circuit temperature and is energized with a supply voltage, and supplies a detection signal having a frequency that varies with variations in the circuit temperature, variations in the supply voltage, or both. The comparison circuit receives the reference signal and the detection signal and, in response to the reference signal, selectively determines the frequency of the detection signal, determines a frequency difference between two or more of the determined frequencies, and supplies a tamper detect signal if the determined frequency difference exceeds a predetermined difference threshold.