Sgs-thomson Microelectronics S.a.

Thomson Semiconducteurs

Thomson Composants Militaires Et Spatiaux

Thomson Composants Militaires Et Spaciaux

Serge Fruhauf

Richard P Fournel

Francedillaois Pierre Tailliet

Laurent Sourgen

Alexis Marquot

Francois Tailliet

Gilles Lisimaque

Gerard S De Ferron

Eric Mattera

Michel Martin

Freeric Breugnot

A fuse for an integrated circuit is constituted by a shallow NP junction, covered with a metal contact, the semiconductor region being not excessively doped. For the blowing of the fuse, the junction is forward biased with a current sufficient to enable a diffusion of metal up to the junction. This short-circuits the junction. The detection is done also by the forward biasing of the junction, but with a low current or a low voltage. The detection can also be done with reverse biasing.

Physical fuse for semiconductor integrated circuit

Method of irreversibly locking a portion of a semiconductor device

Circuit for the detection of temperature threshold, light and unduly low

A circuit for the detection of a fuse with oxide vertical fusing has another fuse that is of the same type but cannot be blown and, in parallel with each of the fuses, a voltage reference circuit. The output of each of the voltage reference circuits is an input of a differential comparator. This differential comparator is preferably provided with a voltage reference circuit that is independent of the supply voltage Vcc.

Circuit for detection of the state of an integrated circuit fuse in a

Some integrated circuits need to be protected against malfunctioning due to the variations in the supply voltage Vcc. A detector of fast variations of the supply voltage is placed in the integrated circuit to interrupt or modify all or a part of the working of the general integrated circuit in the event of the occurrence of fast variation in Vcc. The detector includes a capacitor, a current limiter, a charging circuit, and a detection transistor. The current limiter is a transistor mounted as a diode. The charging circuit uses the supply voltage to charge the capacitor through the current limiter. The relatively stable voltage of the capacitor is applied to the gate of the detection transistor, which has a threshold voltage Vtp. The source of the detection transistor is connected to the voltage supply Vcc. If Vcc varies suddenly, the detector is made conductive. The assembly uses the difference between the threshold voltage Vtn of the current limiter and the threshold voltage Vtp of the detection transistor.

Detector of fast variation in the supply of integrated circuits

In a semi-conducting integrated circuit, there is made a light detection circuit, the output signal of which can be used to counter manipulations by dishonest persons who undertake a decapsulation or a removal from the card when the integrated circuit is inserted in a bank type card, or even a depassivation of the upper protective layer of this integrated circuit, in order to reveal the secret functioning of the circuit or to modify its characteristics. The detector comprises a current generator delivering a current of limited intensity which flows into a reversed biased electronic junction. When the junction is subjected to light, the reverse current that can be allowed into the junction increases. Since the current generator is not capable of putting through stronger current, the voltage at the terminals of the junction drops. This drop in voltage is used as information that reveals the illumination.

Light detection circuit having a junction reverse-biased by a current

The disclosure concerns the safety of the confidential information contained in integrated circuits. In a certain number of integrated circuit applications and, more particularly, in the circuits contained in cards known as 'chip cards', it is necessary to prohibit access by unauthorized persons to confidential information stored in a memory of the circuit. To prevent the fraudulent practice of examining the current consumption at the terminals of the integrated circuit during an operation of reading or writing in the memory, a protection circuit is used. This protection circuit actuates the simulation, according to a pseudo-random sequence generated by a generator, of current consumption values identical to those of real memory cells.

Safety device against the unauthorized detection of protected data

A threshold temperature detection is made by measuring the reverse saturation current of a transistor subjected to the temperature to be measured. It is shown that, for temperatures close to the ambient temperature, the sensitivity of this detector is very high. Furthermore, in making a circuit that measures the relative variations of the reverse saturation current, a temperature detector is made which is independent of variations in characteristics resulting from manufacturng tolerances for integrated circuits. This circuit is particularly designed to be implanted in the same substrate as a memory circuit of the type with memory cells, provided with floating gate transistors.

Temperature threshold detection circuit

An electrically programmable non-volatile memory includes a matrix of memory cells accessible by rows and columns, write and read circuits which apply potentials, representing the programmed datum or representing the read command, to the rows and columns. The memory also includes a device which controls the interconnection of the write and read circuits with the memory cells, wherein N memory cells are programmed simultaneously, N being greater than 1, each memory cell setting up a current surge when it is programmed at '1'. The memory also includes a device for deactivating, one by one, the write circuits corresponding to the N memory cells where there is a change-over from a programming mode to a read mode, and a structure to short-circuit the deactivation device at the change-over to the programming mode.

Electrically programmable non-volatile memory having sequentially

A voltage switch-over circuit, depending on a switch-over signal, delivers either a first voltage Vpp or a second voltage Vcc at its output, the voltage Vpp being greater than the voltage Vcc. The said circuit consists of a first MOS transistor with one of its electrodes connected to the voltage Vcc and a set of two series-connected MOS transistors with one of their electrodes connected to the voltage Vpp and with their two gates connected together so as to create a floating node at the common point between the two MOS transistors, the other electrode of the first MOS transistor and the other electrode of the set of two MOS transistors being connected together, and the gates of the first MOS transistor and those of the set of two MOS transistors respectively receiving the switch-over signal and the reverse switch-over signal.

MOS technology voltage switch-over circuit

In a memory consisting of a matrix of memory cells, each of which is accessible by rows and columns and is connected to write and read circuits which are used, respectively, to programme them in two states, '1' or '0', depending on the input data, and to read the programmed state, the memory cells being of the type that require a programming current in order to be programmed in a first state or '1' and require no current to be programmed in a second state or '0', the safety device consists of a simulation circuit activated by data corresponding to a '0' programming operation and delivering a current identical to that of a memory cell in the '1' programming condition.

Safety device for the programming of an electrically programmable

A fraud-preventive device for a memory card comprising an EPROM type or similar non-volatile memory designed to receive confidential authorization data as well as the results, wrong or otherwise, of tests on the authorization data, comprises a single simulation cell designed to record the non-erroneous results, this cell consuming the same current as a memory cell, which has never been programmed, of the memory part designed to record the wrong data.

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Peynier, France

Serge Fruhauf