Abstract: A binary frequency divider includes a counter paced by an input signal, means for comparing a counting value with first and second threshold values and supplying first and second control signals synchronized with variation edges of a first type of the input signal. The divider includes means for supplying at least one third control signal shifted by a half-period of the input signal in relation to one of the first or second control signals, and control means for generating the output signal using control signals chosen according to the value of at least one least significant bit of the division setpoint. Application is mainly but not exclusively to UHF transponders.

Abstract: A method and a system for authenticating an electronic tag by a host communicating with this tag via a reader, including: calculating, on the tag side, a first digital signature using at least one first function shared by the tag and the reader, taking into account at least one first secret key known by the electronic tag and the reader only; transmitting the first signature to the reader; calculating, on the reader side, a second digital signal using at least one second function, different from the first function and shared by the reader and the host, taking the first signature into account; transmitting the second signature to the host; and checking, on the host side, the coherence between the second signature and a validation value calculated based on said second function and on a second secret key known by the host and by a single element selected from among the tag and the reader.

Abstract: A method checks the state of a set of memory cells of a memory having memory cells arranged in a memory array, row and column decoders for selecting a memory cell, and a sense amplifier for supplying a state of the selected memory cell depending on whether the selected memory cell is conductive or non-conductive. The method includes features wherein all the memory cells of a set grouping together several memory cells are selected, and then simultaneously coupled to the sense amplifier, and the sense amplifier supplies a global state of all the selected memory cells to which it is coupled, if the latter are simultaneously non-conductive. Application is provided to the checking of a command for block-erasing a memory.

Abstract: A method for executing a write command for writing a binary word in a programmable memory, comprises writing each of the bits in a programmed state of a binary word to be written in a corresponding memory cell of the memory, reading each bit of the word written in the memory corresponding to a bit in the programmed state of the word to be written, comparing each bit in the programmed state of the word to be written with a corresponding bit read in the memory, and generating an error signal if at least one bit of the word to be written in the programmed state is different from the corresponding bit read. Application of the method can be particularly but not exclusively to integrated circuits for chip cards.

Abstract: A method protects against a global data erasure an integrated circuit comprising an electrically programmable data memory and a control unit to execute commands for reading or writing in the memory. The method includes the steps of providing, in the integrated circuit, electrically programmable reference memory cells, at putting the integrated circuit into service, storing, in the reference memory cells, bits of determined value forming an authorized combination of bits and, during the operation of the integrated circuit following its putting into service, reading and evaluating the reference memory cells and blocking the integrated circuit if the reference memory cells contain a forbidden combination of bits different from the authorized combination.

Abstract: A method for modulating the impedance of an antenna circuit supplying pump signals to a charge pump comprising at least one first pump stage and one last pump stage, the last pump stage supplying a continuous voltage. The output of the first pump stage is short-circuited by means of a switch and the last pump stage goes on pumping electric charges and supplying the continuous voltage. Application in particular to RFID passive transponders.

Abstract: A persistent volatile memory cell memorizes a binary datum during a retention time independent from a supply voltage of the memory cell. The memory cell comprises a capacitive memory point supplying a persistent voltage and having a determined discharge time, a switch for triggering the discharge of the memory point when an erase signal has an active value, a switch for triggering the charge of the memory point when a write signal has an active value, and a sense-amplifier circuit having an input receiving the persistent voltage, and an output supplying the binary datum. The memory cell can be applied to the management of an inventory flag in a contactless integrated circuit.

Abstract: A method and device for generating a clock signal, the method including measuring, using a first clock signal, a characteristic of a reference event in a received signal, determining, using the first clock signal, a variation of a characteristic of a second event in a received signal, correcting the measurement according to the variation of the characteristic of the second event, and generating a second clock signal using the first clock signal according to the corrected measurement.

Abstract: A method for configuring a memory space, the method including reading a piece of configuration information in the memory space, determining a division of at least one part of the memory space into memory banks according to the configuration information read; and allocating to each of the memory banks an access number to be used to access a data location in the memory bank, in combination with a logic address of the location in the memory bank.

Abstract: A contactless integrated circuit receiving an RF signal comprises a clock-signal generator to produce a clock signal from a first half wave and a second half wave representing the received RF signal. Also disclosed is a method for the generation of a clock signal in which the first half wave and the second half wave are compared to produce the clock signal. The invention is adapated for use in contactless cards, transponders, and the like.

Abstract: A method for executing a write command for writing a binary word in a programmable memory, comprises writing each of the bits in a programmed state of a binary word to be written in a corresponding memory cell of the memory, reading each bit of the word written in the memory corresponding to a bit in the programmed state of the word to be written, comparing each bit in the programmed state of the word to be written with a corresponding bit read in the memory, and generating an error signal if at least one bit of the word to be written in the programmed state is different from the corresponding bit read. Application of the method can be particularly but not exclusively to integrated circuits for chip cards.

Abstract: A method divides a number N1 by a number which can be written in the form 2n/k, n and k being whole numbers, and obtains a result N2. The result N2 is calculated by adding terms N1*Ki/2n-i for i ranging from 0 to N, the terms Ki being the constituent bits K0, K1, K2, . . . KN-1 of the number k expressed in binary. The method can be applied particularly to the production of a calibration circuit for calibrating a clock signal in a UHF transponder.

Abstract: A method for generating a variable number includes generating a clock signal, demodulating a received signal of data transmission, supplying a binary signal having variable frequency pulses, and sampling the clock signal by the binary signal to generate bits of a variable number. The method can be applied to RFID tags.

Abstract: A method protects against a global data erasure an integrated circuit comprising an electrically programmable data memory and a control unit to execute commands for reading or writing in the memory. The method comprises the steps of providing, in the integrated circuit, electrically programmable reference memory cells, at putting the integrated circuit into service, storing, in the reference memory cells, bits of determined value forming an authorized combination of bits and, during the operation of the integrated circuit following its putting into service, reading and evaluating the reference memory cells and blocking the integrated circuit if the reference memory cells contain a forbidden combination of bits different from the authorized combination.

Abstract: A method checks the state of a set of memory cells of a memory comprising memory cells arranged in a memory array, means for selecting a memory cell, and a sense amplifier for supplying a state of the selected memory cell depending on whether the selected memory cell is conductive or non-conductive. The method includes features wherein all the memory cells of a set grouping together several memory cells are selected, and then simultaneously coupled to the sense amplifier, and the sense amplifier supplies a global state of all the selected memory cells to which it is coupled, if the latter are simultaneously non-conductive. Application is provided to the checking of a command for block-erasing a memory.

Abstract: The invention concerns non-contact smart cards and, more particularly in such cards, a circuit for detecting data frames and providing them with a parallel format for their processing. The invention is characterised in that it consists in using the information contained in the first octets of the frame being currently received, thereby enabling to identify them as they are received and route them into registers (80). This is provided by a state machine (60) whereof the shift from one state to the other is switched by the circuitry (62, 76) output signals.

Abstract: A method of reading a group of memory words from an integrated circuit memory of a contactless tag, comprising the sending by a remote interrogation unit to the contactless tag of a specific command for reading the group of memory words from a given start address, the initialization of an address counter for the contactless tag to the value of the given start address, and the sending by the contactless tag of the memory word at the start address, as well as an iterative process comprising in succession a first step of sending by the remote interrogation unit to the contactless tag of an incrementation marker recognizable by the contactless tag, a second step of incrementation of the address counter for the contactless tag in response to the incrementation marker, and a third step of sending by the contactless tag to the remote interrogation unit of a data frame comprising the memory word stored in the memory at the address pointed at by the current value of the address counter.

Abstract: An electromagnetic transponder and a method for controlling by pulse trains a switch for modulating the load of this transponder in an electromagnetic field from which it extracts its power supply, the duty ratio of the pulses being controlled according to the transponder supply voltage.

Abstract: A power-on reset device for an electronic circuit includes an output terminal for delivering a reset signal. The reset signal may be active or inactive as a function of a supply voltage. A comparison node is coupled to the output terminal by way of at least one inverter. A first current source assembly delivers a first current to charge or discharge the comparison node. The first current is dependent on the supply voltage and on a specified current value, and is at maximum equal to this specified value. A second current source assembly delivers a second current to discharge or charge the comparison node. This second current is substantially independent of the supply voltage.

Abstract: A memory for a contactless tag of the RFID type is configured to receive a deactivation command. The memory includes a group of memory words that are suitable for storing an identifier of the tag and are write-accessible via a standard write command. The memory further includes at least one additional memory word suitable for storing a deactivation value. The detected presence of the deactivation value makes it possible for the tag to prevent reading and/or the transmission of the identifier in response to a radio interrogation signal.