摘要:
To protect integrated circuits as efficiently as possible against electrostatic discharges, by putting a diode in avalanche mode without untimely triggering of this avalance mode by overvoltages of non-electrostatic origin, the following solution is proposed: through an insulated gate surrounding the cathode of the diode, the threshold for transition into avalanche mode of the diode is modified according to the slope of the overvoltages appearing at the terminal to be protected. The gate is connected to the terminal by an integrating circuit in such a way that the overvoltages are applied to the gate with a certain delay, inducing a potential difference between the cathode and the gate which is all the greater as the front of the overvoltage is steep. The avalanche triggering threshold is higher in the latter case than in the former one, and it is thus distinguish between overvoltages of diverse origins.
摘要:
The present invention relates to a random signal generator (10) comprising means (11, 12, 13) for converting an electronic noise (N, N1, N2) into a logic signal (RS) whose value depends on the random fluctuations of the electronic noise (N). According to one embodiment, the generator (10) comprises at least two delay lines (11, 12) having initially balanced time constants (T). The two delay lines (11, 12) receive a pulsed reference signal (Hr) at input and at least one of the delay lines (11, 12) receives an electronic noise (N1, N2) causing its time constant (T) to fluctuate (&Dgr;t). The temporal lag between the two pulsed signals (S1, S2) is detected by a circuit (13) delivering a logic signal (RS) whose value is a function of the relative lag between the two pulsed signals (S1, S2). Advantageously, the electronic noise (N1, N2) is a differential noise taken at two points (GND1, GND2) of a ground plane or two points (PV1, PV2) of an electrical supply plane.
摘要:
The invention concerns an integrated circuit comprising a resonant circuit (L,20) for receiving by electromagnetic induction an alternating voltage (V.sub.ac), the resonant circuit comprising at least one capacitance (C1-Ci) switchable by means of a programmed switch (11), the switch comprising a circuit breaker (7), a memory cell (6) and a circuit (31, 32, 33, 42) for controlling the circuit beaker (7), the control circuit being supplied by the alternating voltage (V.sub.ac) and arranged for opening or closing the circuit breaker (7) depending on the programming or the erasing status of the memory cell (6).
摘要:
Encryption circuits and methods, in particular for smart cards, are disclosed. Smart cards without microprocessors may be authenticated very simply by using encryption with a secret card data table on which recursive cycles are executed. During each cycle, a word is read out of the table, said word being at an address that is at least partially defined by the word read out in the previous cycle. The new address preferably consists of several bits from the previous word and a bit from internal card data, external data supplied by a card reader, or a register containing a partial encryption result.
摘要:
A process to protect against tampering with integrated circuits. During manufacture, a secret code is written in a secret address (102) of a memory (101) of the integrated circuit and an internal logic (103-108) blocks writing into this portion of memory, the testing of the integrated circuit and the read-out of data. In order to unlock the integrated circuit, the secret address is read while applying a secret code to an input of the integrated circuit. A comparison (207) of the secret code as read and the secret code applied to the integrated circuit then either locks or unlocks the integrated circuit. This unlocking is done in irreversible manner. Thus, it is possible to transport integrated circuits between a manufacturer and a remote users, without fear of the circuits being stolen, because if stolen, they would be inoperable without the secret codes.
摘要:
A novel expression system using the heat-inducible bovine hsp70A promoter and associated cis-acting elements is disclosed. The system provides for the continuous production of a highly pure, authentic protein, substantially free of infectious viral and cellular protein contaminants.
摘要:
In a memory cell of an EEPROM or flash-EEPROM memory, the source and the drain of a floating-gate transistor forming the non-volatile memorizing device are connected together. It is shown that the capacitive behavior of the cell is then differentiated at the time of the reading depending on whether it is in a programmed state or in an erased state. This difference in behavior is used to differentiate the logic states.
摘要:
In a memory card designed to count down a number of units by successive programming of non-volatile, electrically erasable and electrically programmable memory cells, the memory is organized into N rows of P cells, the weight of the cells of one row in the account being P times the weight of the next-ranking row. The countdown procedure is recurrent and consists in making a search, in scanning the memory according to the rising order of weights, of an erased cell, programming this cell and an erased cell and then erasing the entire row having an immediately lower rank unless the erased cell is located in the first row, and in recommencing this recurrent procedure until an erased cell is found in the first line. The auxiliary cell enables the detection of an abnormal interruption of the recurrent procedure and the restoring of the exact account of the memory which could have been distorted by this abnormal interruption.
摘要:
A circuit to produce a voltage Vpp from a lower voltage supply Vcc is useful, for example, to produce the voltage for programming the cells of an electrically programmable memory. The circuit has a load pump (PMP), a regulator (REG) to interrupt the working of the load pump when the voltage Vpp exceeds a predetermined voltage (Vpp0), a transistor (T1) to interrupt the current consumption of the regulator when the load pump is interrupted, and a control circuit (CTRL) to then monitor the voltage Vpp and ascertain that it does not drop by more than a small value dV below Vpp0 and to restart both the load pump and the current supply of the regulator if the voltage drops more than dV.
摘要:
The invention concerns interface circuits for chip card readers. It consists of providing link connections between this circuit and the reader, these connections being identical to those established between the circuit and the chip card. An internal switch (102) in the circuit is used to link these connections together, or to a control register (101), which is internal to the circuit, and actuated by an additional control connection. With the invention, it is possible to limit the number of connections between the circuit and the reader and to control the circuit with a software interface which is identical to the control interface of a chip card.