Stmicroelectronics S.r.l.

Sgs-thomson Microelectronics S.r.l.

Stmicroelectronics International N.v.

Danilo Rimondi

Carolina Selva

Cosimo Torelli

Rita Zappa

Ashish Kumar

Michele Taliercio

Andrea Baroni

Donatella Brambilla

Giovanni Mastrodomenico

An embodiment of a memory device of SRAM type is proposed. The memory device includes a plurality of memory cells each for storing a first logic value represented by a first reference voltage or a second logic value represented by a second reference voltage. Each memory cell includes a bistable latch&#x2014;having a main terminal, a complementary terminal, a set of main storage transistors for maintaining the main terminal at the reference voltage corresponding to the stored logic value, and a set of complementary storage transistors to maintain the complementary terminal at the reference voltage corresponding to the complement of the stored logic value&#x2014;a main access transistor and a complementary access transistor for accessing the main terminal and the complementary terminal, respectively. The memory device may further include biasing means for modifying a value of a threshold voltage of at least one of the main transistors to a first threshold voltage value or to a second threshold voltage value and for modifying a threshold voltage value of at least one of the complementary transistors to the second threshold voltage value or to the first threshold voltage value during a write operation of the first logic value or of the second logic value, respectively, in the memory cell.

Dynamically configurable SRAM cell for low voltage operation

A static random access memory (SRAM) device includes a memory array of a plurality of memory cells, a controller that receives an external clock signal formed by a succession of external pulses and generates an internal clock signal formed by a succession of internal pulses, and a driving circuit that receives the internal clock signal. The controller is operable in a first mode, wherein the controller generates, for each external pulse, a corresponding internal pulse and the controller controls the driving circuit so that the driving circuitry carries out one access to the memory array for each internal pulse. The controller is further operable in a second mode, wherein the controller generates, for each external pulse, a pair of internal pulses, and the controller controls the driving circuitry so that, for each pair of internal pulses, the driving circuitry writes a first data item in a set of memory cells, and then reads the set of memory cells, so as to acquire a second data item.

SRAM memory device and testing method thereof

A method for testing a memory device. The memory device includes a matrix of memory cells having a plurality of rows and columns; the matrix includes a plurality of rows of operative memory cells each one for storing a variable value and at least one row of auxiliary memory cells each one storing a fixed value. The memory device further includes writing circuitry for writing selected values into the operative memory cells, and reading circuitry for reading the values being stored from the operative or auxiliary memory cells. The method includes reading output values from the row of auxiliary memory cells, determining a malfunctioning of the memory device in response to a missing match of the output values with the fixed values, determining a cause of the malfunctioning according to a pattern of reading errors between the output values and the corresponding fixed values, and providing a signal indicative of the cause of the malfunctioning.

Integrated solution for identifying malfunctioning components within memory devices

An embodiment of a memory device of SRAM type integrated in a chip of semiconductor material is proposed. The memory device includes a plurality of memory cells each for storing a binary data having a first logic value represented by a first reference voltage or a second logic value represented by a second reference voltage. Each memory cell includes a bistable latch&#x2014;having a main terminal, a complementary terminal, a set of field effect main storage transistors coupled to the main terminal for maintaining the main terminal at the reference voltage corresponding to the stored logic value or to a complement thereof, a set of field effect complementary storage transistors coupled to the complementary terminal for maintaining the complementary terminal at the reference voltage corresponding to the complement of the logic value associated with the main terminal&#x2014;and a field effect access transistor for accessing the main terminal. The chip includes an isolated well, the access transistor and at least one of the complementary storage transistors being formed in the isolated well.

5T SRAM memory for low voltage applications

An embodiment of a memory device includes a plurality of memory cells; each memory cell includes a latch adapted to store an information bit. Said latch includes a first logic gate including a first input terminal and a first output terminal and a second logic gate including a second input terminal and a second output terminal. Said first input terminal is connected to said second output terminal and said first output terminal is connected to said second input terminal. The memory device further includes reading and writing means adapted to perform a read operation or a write operation of the information bit. Said first logic gate includes a pull-up branch coupled between a terminal for providing a supply voltage and the first output terminal, and a pull-down branch coupled between the first output terminal and a terminal for providing a reference voltage. Said second logic gate includes a pull-up branch coupled between a terminal for providing the supply voltage and the second output terminal, and a pull-down branch coupled between the second output terminal and a terminal for providing the reference voltage. Said memory device includes variation means adapted to selectively vary a gain factor of at least one between the pull-down branch and the pull-up branch of said first logic gate and second logic gate depending on the operation performed by the reading and writing means.

Adjustable impedance SRAM memory device

A method is for making an integrated circuit with built-in self-test. The method includes forming at least one nonvolatile read only memory (ROM) to store ROM code and forming a logic self-test circuit to verify a correct functioning of the at least one nonvolatile ROM. Moreover, the method includes defining, in the logic self-test circuit, a logic self-test core to process the ROM code and to generate a flag based upon a control signature and defining, in the logic self-test circuit, a nonvolatile storage block, coupled to the logic self-test core, to store the control signature. Furthermore, the method includes writing the ROM code to the at least one nonvolatile ROM and writing the control signature to the nonvolatile storage block, during a same fabrication step.

Process and system for the verification of correct functioning of an on-chip memory

A self diagnosis (BISD) device for a random memory array, preferably integrated with the random access memory, executes a certain number of predefined test algorithms and identifies addresses of faulty locations. The BISD device recognizes certain fail patterns of interest and generates bit-strings corresponding to them. In practice, the BISD device may diagnose memory arrays and allow the identification of defects in the production process that affect a new technology during its learning phase, thus accelerating its maturation.

Built-in self diagnosis device for a random access memory and method of diagnosing a random access

A built-in self-test and self-repair structure (BISR) of memory arrays embedded in an integrated device includes at least a test block (BIST) programmable to execute on a respective memory array of the device any of a certain number of test algorithms, and a self-repair block that includes a column address generator processing the faulty address information for allocating redundant resources of the tested memory array. The BISR may further include a redundancy register on which final redundancy information is loaded at each power-on of the device and control logic for managing data transfer from external circuitry to the built-in self-test and self-repair structure (BISR) and vice versa. The BIST structure serves any number of embedded memory arrays even of different types and sizes.

Programmable multi-mode built-in self-test and self-repair structure for embedded memory arrays

A memory cell comprises a first and a second inverters connected in a latch configuration. The inverters have respective first and second means for receiving a first and a second voltage supplies, respectively. The cell also comprises means, responsive to a memory cell selection signal, for selectively connecting an input of at least one of the first and second inverter to at least one respective input/output data line, carrying an input datum to be written in the memory cell in a memory cell write operation and an output datum read from the memory cell in a memory cell read operation. For flash-clearing the memory cell, means are provided for switching at least one of the first and second voltage supply receiving means of at least one of the first and second inverters between the first voltage supply and the second voltage supply. The memory cell is particularly adapted to implement a flash-clear function in a memory device.

Static RAM with flash-clear function

A semiconductor memory cell having a word line, a bit line, a precharge line, an access transistor, and first and second cross-coupled inverters. The first inverter includes a first P-channel transistor and a first N-channel transistor, and the second inverter includes a second P-channel transistor and a second N-channel transistor. The access transistor selectively couples the bit line to an output of the first or second inverter, and one terminal of the first N-channel transistor is connected to the precharge line. In a preferred embodiment, a control circuit is provided that, during a writing operation, supplies data to be written to the memory cell to the bit line, supplies a pulse signal to the precharge line, and activates the word line. A method of writing data to a semiconductor memory cell that is coupled to a word line and single bit line is also provided. According to the method, the level of the bit line is set in accordance with data to be written, the memory cell is precharged so as to force the output of one of the inverters of the memory cell to a predetermined logic level, and the word line is activated to couple the bit line to the memory cell.

Low power SRAM memory cell having a single bit line

A memory device comprises an array of memory cells arranged in rows and columns, a plurality of gates for transmitting respective selection outputs of a row decoder to respective rows, a dummy column of dummy memory cells substantially identical to the memory cells, precharge means for precharging the columns and the dummy column at a precharge potential when no row is selected, and programming means for setting selected columns at respective programming potentials. The device comprises dummy memory cell preset means for presetting the dummy memory cells in a first logic state when no row is selected, dummy column programming means for setting the dummy column at a prescribed programming potential corresponding to a second logic state opposite to the first logic state, and first detector means for detecting that the dummy column has discharged from the precharge potential to the prescribed programming potential and for consequently enabling said plurality of gates. Each of the gates has an input coupled to a respective dummy memory cell so that the gate is disabled as soon as the respective dummy memory cell has switched from the first logic state to the second logic state.

Memory device with reduced power dissipation

The invention relates to a memory comprising a matrix of memory cells; a plurality of gates for transmitting respective selection outputs of a row decoder to respective rows of the matrix; a dummy bit line having an equivalent load as bit lines associated to columns of the matrix and which is discharged by a dummy memory cell when any row is selected; and circuitry for precharging the bit lines and the dummy bit line when no row is selected, and enabling said gates for transmission of the selection outputs of the row decoder in response to a clock signal. Each gate has an input coupled to the dummy bit line such that the gate is disabled as soon as the dummy bit line has discharged to a switching threshold of the gate.

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Mozzo, Italy

Danilo Rimondi