Temic Semiconductor Gmbh

Infineon Technologies Ag

Atmel Germany Gmbh

Michael Bruhnke

Ulrich Friedrich

Werner Blatz

Uwe Weder

Ulrich Grosskinsky

Ferdinand Friedrich

Konrad Hirsch

Viktor Preis

Andreas Sch&uuml;lgen

Marc Melchior

In accordance with the USB specifications, an accuracy of 0.25% is required for the data transmission rate. To generate a clock signal that allows this accuracy, the invention uses a clock generator unit that does not require a crystal. The clock generator unit includes an internal clock generator, a pulse counter that is connected to the internal clock generator, a pulse number memory, and a pulse filter. The pulse counter counts the number of internally generated clock pulses between two pulses of the synchronization signal, which are transmitted in accordance with the USB specification. The difference between the ascertained pulse number and a nominal pulse number is evaluated and is used for controlling the pulse-suppressing pulse filter. This results in a stabilized clock signal.

Clock generator, particularly for USB devices

The method of cryptological authentification in a scanning identification system comprising a base station, which supplies energy via the alternating field to a transponder connected to the object to be identified, includes the following method steps. For essentially the entire communication between the base station and the transponder, the base station generates an inquiry signal. Upon receiving the inquiry signal transmitted by the base station, the transponder responds with an identification number stored in its memory. The base station then encodes a first bit sequence it has generated by using a key bit sequence that is allocated to the identification number of the transponder, and transmits the second bit sequence obtained in this manner to the transponder. When the second bit sequence is received, the transponder generates a checking bit sequence from the second bit sequence, and, following the complete reception of the second bit sequence, transmits this checking bit sequence to the base station. The checking bit sequence serves to verify the correct reception of the second bit sequence. For cryptographic authentification, the transponder encodes the first bit sequence reconstructed from the second bit sequence using the key bit sequence allocated to the transponder, and transmits the third bit sequence obtained in this manner to the base station. While the transponder is still encoding the second bit sequence to form the third bit sequence, the base station uses the checking bit sequence to verify whether an error has occurred in the transmission of the second bit sequence, and may abort the ongoing encoding in the transponder. This can abort the ongoing authentification, because a valid result cannot be anticipated. Thus, time is gained at the start of a new running of the authentification method.

Method of cryptological authentification in a scanning identification system

In a method of transferring data from a transponder to a reading device in a scanning identification system through load-modulation of an inquiry signal emitted by the reading device, with the transponder being initialized at the beginning of the reception of the inquiry signal and responding with the emission of the response signal, first a predetermined number of data bits that are not part of the response signal are transmitted, and a terminator sequence followed by the response signal are repeatedly transmitted, until the inquiry signal is interrupted. The time required by the reading device for building up the inquiry field is bridged by the predetermined number of data bits and, at the same time, the reading device is synchronized to the clock of the response signal. Through the terminator sequence, which indicates the beginning of a valid response signal, the response signal is already recognized correctly by the reading device during the first transfer.

Data transfer method for a scanning identification system

The invention relates to a method for calibrating an oscillating receiver circuit of a transponder in an RFID system to resonance to the frequency of an inquiry signal transmitted by a reader, the oscillating receiver circuit comprising at least one inductive resistor and at least one capacitor. Immediately after the start of reception of the inquiry signal, capacitors are connected in increments to the capacitance of the oscillating receiver circuit until such time as the rectified, smoothed inquiry signal assumes a maximum voltage value. This active self-calibration is performed upon each initialization of the transponder but can also be addressed by having the reader send a special sequence to the transponder.

Method for tuning an oscillating receiver circuit of a transponder built into a RFID system

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München, Germany

Michael Bruhnke