Infineon Technologies Ag

Henning Lorch

Joerg Berthold

Jörg Berthold

Brigitte Wirtz

Stefan Jung

Ernst Haselsteiner

Martin Eisele

A method for analyzing fingerprint images includes picking up a sequence of images at very short time intervals, while a finger is being placed onto an electronic fingerprint sensor. A criterion for recognizing a live finger is extracted from variations in the images. The images are defined as a pixel raster having different gray values, with the aid of which the pixels are assigned binary values of zero or one. Significant changes in the values are detected and compared, with the aid of distinctive numbers or the like, to known typical changes that occur regularly in a particular image class.

Method for analyzing fingerprint images

A method and circuit arrangement for determining performance of a digital circuit to a critical degree by the transit time of signals of the longest signal path, also called the critical path. Since the signal transit time is influenced by the operating voltage, by regulating the operating voltage, to compensate for the effects caused by temperature and process fluctuations on the signal transit time in the digital circuit. In particular, the operating voltage can be regulated as a function of the signal transit time in such a way that a required minimum operating frequency can always be achieved. To determine signal transit time, the digital circuit has associated with it a number of replicas of the critical path in the digital circuit upon which the signal transit time is determined. In order to determine the transit time, the signal path replicas are exposed to the same operating conditions as the digital circuit. Also, to allow a safety margin to be obtained, the signal path replicas have additional circuit elements that further slow down the signal transit times on the signal path replicas. Further, the mean of the transit times on the signal path replicas is determined.

Method and circuit arrangement for regulating the operating voltage of a digital circuit

A method of determining the critical path of a circuit includes first determining the paths, their mean path transit times and their path transit time fluctuations. Paths having similar statistical parameters are combined to form one path group. For each path group, a statistical group figure is, then, calculated and, for the totality of paths considered, a statistical total figure is calculated. Finally, the critical paths of the circuit are determined by taking into consideration the total figure, comparing the group figures at or above a critical path transit time Tc.

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Munich, Germany

Henning Lorch