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:
Mar. 20, 2012
Filed:
Jan. 20, 2008
Johannes A. J. Van Geloven, Eindhoven, NL;
Robertus A. M. Wolters, Eindhoven, NL;
Nynke Verhaech, Arnhem, NL;
Johannes A. J. Van Geloven, Eindhoven, NL;
Robertus A. M. Wolters, Eindhoven, NL;
Nynke Verhaech, Arnhem, NL;
NXP B.V., Eindhoven, NL;
Abstract
An integrated circuit has an inhomogeneous protective layer or coating over a circuit to be protected, and a sensing circuit () arranged to sense a first impedance of a part of the protective coating compared to a reference impedance (CO) located on the integrated circuit. The sensing circuit is able to measure a change in the first impedance, e.g. caused by tampering. The sensing circuit has an amplifier (OTA) having a feedback loop, such that the impedance being sensed is in the feedback loop. The sensing circuit can be incorporated in an oscillator circuit (OTA, Comp) so that the frequency depends on the impedance. Where the impedance is a capacitance, sensing electrodes adjacent to the protective layer or coating, form the capacitance. The electrodes can be arranged as selectable interdigitated comb structures, so that the protective layer or coating extends in between the teeth of the comb structures.