Stmicroelectronics S.r.l.

Michele La Placa

Ignazio Martines

Fabio Enrico Carlo Disegni

Carmelo Condemi

Maurizio Giovanni Gaibotti

Michelangelo Pisasale

Federico Goller

Antonio Giambartino

Antonino Mondello

Maurizio Francesco Perroni

Cesare Torti

Vincenzo Sambataro

In an embodiment, a method includes receiving, between a positive input terminal and a negative input terminal, a supply voltage, receiving a data signal, generating, by a voltage generator in a branch of a plurality of branches, a branch current as a function of a respective driving signal and of a regulated voltage, each branch connected between the positive input terminal and the negative input terminal, selectively activating the voltage generator as a function of a respective enabling signal and providing, between a positive output terminal and a negative output terminal, the regulated voltage to one or more driving circuits.

Phase change memory with supply voltage regulation circuit

An embodiment voltage generation circuit, for a memory having a memory array with a plurality of memory cells coupled to respective wordlines and local bit-lines, each having a storage element and selector element, a bipolar transistor being coupled to the storage element for selective flow of a cell current during reading or verifying operations, and a base terminal of the selector element being coupled to a respective wordline; associated to each bit-line is a biasing transistor having a control terminal, and the circuit generates a cascode voltage for this control terminal; a driver stage is coupled to one end of each wordline. The circuit generates the cascode voltage based on a reference voltage, which is a function of the emulation of a voltage drop on the driver stage, on the wordline, and on the memory cell as a result of a current associated to the corresponding selector element.

Bit-line voltage generation circuit for a non-volatile memory device and corresponding method

A voltage regulator and a phase change memory are disclosed. In an embodiment a phase-change memory includes an array of a plurality of phase-change memory cells, an address decoder configured for receiving an address signal and selecting a sub-area in the array of the plurality of memory cells, the selected sub-area having a given number of bits of a data signal and a writing circuit including a control circuit configured for receiving the data signal and determining, for each memory cell in the selected sub-area, whether a respective bit of the data signal indicates that the memory cell is to be changed from the amorphous state to the polycrystalline state and one or more driving circuits supplied via a regulated voltage and configured for applying the set current for the first interval to the memory cells that are to be changed from the amorphous state to the polycrystalline state.

A reading circuit for a semiconductor memory, comprising: a circuital branch adapted to be electrically coupled to a bit line which is connected to a memory cell to be read; an evaluation circuit adapted to sense a cell electric current flowing through the bit line during a sensing phase of a reading operation of the data stored into the memory cell, the evaluation circuit comprising a negative feedback control loop adapted to control the potential of the bit line during the sensing phase, the control loop comprising a differential amplifier having an inverting input terminal operatively connected to the bit line, a non-inverting input terminal fed by a first reference potential, and a feedback circuital path connected between an output of the differential amplifier and the inverting input, wherein the feedback circuital path is adapted to conduct a measure current corresponding to the cell electric current, and comprises current/voltage conversion means for converting the measure current into a corresponding voltage. The conversion means of the feedback circuital path comprises at least one first transistor arranged to conduct the measure current, and biasing means adapted to bias the at least one first transistor so as to emulate the behavior of a resistor.

Sense amplifier with reduced area occupation for semiconductor memories

A sensing circuit for a semiconductor memory, includes, a detecting amplifier including a first circuital branch is run through by a first current corresponding to the sum of a second current as a function of a comparison current and a cell current. The cell current is a function of a state of a memory cell to be read in a predetermined biasing condition. A second circuital branch is coupled as a current mirror configuration with the first circuital branch. The second circuital branch is run through by a third current proportional to the first current. A third circuital branch coupled to the second branch sinks a fourth current as a function of the comparison current. A fourth circuital branch coupled to is run through by a residual current equal to the difference between the third and the fourth current. The residual current assumes different values depending on the fact that the cell current is lower, equal or higher than the comparison current. A residual current sensitive means generates an indication of the state of the memory cell as a function of a value of the residual current.

Sense amplifier circuit and method for semiconductor memories with reduced current consumption

An output CMOS buffer includes MOS enhancement transistors and has a second complementary pair of natural or low threshold transistors, connected respectively in parallel to transistors of opposite type of conductivity of the complementary pair of enhancement MOS transistors of the final buffer stage. The gate terminals of the pair of natural or low threshold transistors are controlled by respective inverters, each supplied through a slew rate limiter of the slope of the driving current and are respectively connected between the positive supply node of the output buffer and a negative (below ground potential) node and between the common ground node of the output buffer and a positive supply node. The negative voltage and the positive voltage on the nodes are at least equal to the absolute value of the threshold voltage of the natural or low threshold transistors.

High speed CMOS output buffer for nonvolatile memory devices

An output buffer for providing a buffered current to a circuit load includes a plurality of operative stages, each one for generating a component of the buffered current and an enabling circuit for selectively enabling each operative stage. The output buffer further comprises at least one auxiliary stage and control means for measuring a control current that can be delivered by the at least one auxiliary stage and for activating the enabling means according to the measured control current.

Output buffer circuit and method with self-adaptive driving capability

An architecture for implementing an integrated capacity includes a capacitive block inserted between first and second voltage reference. The block is formed The block is formed from elementary capacitive modules. An enable block is inserted between the first voltage reference and the capacitive block and includes switches connected to the elementary capacitive modules and driven on their control terminals by control signals. Each switch of the enable block is inserted between the first voltage reference and a first end of a corresponding elementary capacitive module. A verify and enable circuit is connected to the first voltage reference, as well as at the input of the first end of the elementary capacitive modules and at the output of the control terminals of the switches of the enable block. The verify and enable circuit detects the presence of a current value in each of the elementary capacitive modules and, if said current is detected, disables that elementary capacitive module of the capacitive block using the corresponding switch of the enable block.

Architecture for implementing an integrated capacitance

A voltage-down converter for providing an output voltage lower than a power supply voltage of the converter is proposed. The converter includes voltage regulation means for obtaining an intermediate voltage corresponding to the output voltage from the power supply voltage by controlling a variable-conductivity element with a control signal resulting from a comparison between the intermediate voltage and a reference voltage, and an output stage for obtaining the output voltage from the power supply voltage by controlling a further variable-conductivity element with the control signal, wherein the further variable-conductivity element has a modular structure with at least one set of multiple basic modules, the converter further including means for enabling and/or disabling the modules of each set in succession according to a comparison between the output voltage and the intermediate voltage.

Voltage down-converter with reduced ripple

A method for simultaneously programming a pre-established number of memory cells includes setting an initial number of memory cells to be simultaneously programmed equal to the pre-established number, and subdividing the initial number of memory cells to be programmed into subsets of memory cells. A program operation for simultaneously programming all the memory cells of each subset of memory cells is executed by forcing a current through all the memory cells of each subset of memory cells. The current has a program voltage associated therewith. The program voltage is compared to a threshold voltage during execution of the program operation. The method further includes stopping execution of the program operation if the threshold voltage is surpassed, reducing the initial number of memory cells to be simultaneously programmed, and restarting from the subdividing.

Method and circuit for simultaneously programming memory cells

The output buffer stage includes a half-bridge output stage having a first pair of complementary drivers connected in series between a supply line and a ground node, the high impedance state or conduction state of which is determined through a pair of control phases. The buffer stage includes a pair of switches controlled by the control phases, connected in series between them and connecting the transistors of the first stage in series. Each driver is connected in series with a switch, that is quickly opened to prevent under-threshold currents from circulating when the respective driver is turned off, and that is rapidly turned off when the respective driver is turned on.

Output buffer stage

Described herein is a reading circuit for a nonvolatile memory device, wherein the currents flowing through an array memory cell to be read, and a reference memory cell with known contents, are converted into an array voltage and, respectively, into a reference voltage, which are compared to determine the contents of the array memory cell. The method envisages reducing the electrical stress to which the reference memory cell is subjected during reading, by generating and holding a sample of the reference voltage, then deselecting the reference memory cell, and then continuing reading using the sample of the reference voltage.

Reading circuit and method for a nonvolatile memory device

A sense amplifier for reading a non-volatile memory cell includes a bitline current path connected to a non-volatile memory cell to be read, and a reference current path connected to a reference memory cell. A current mirror includes an input transistor and a corresponding input node, and an output transistor and a corresponding output node. The current mirror converts currents in the reference current path and the bitline current path to respective voltages on the input and output nodes. An equalization circuit equalizes the voltages on the input and output nodes of the current mirror and is activated by a command signal. The equalization circuit includes a switch controlled by the command signal, and a diode-connected load transistor connected in parallel to the output transistor of the current mirror and connected to the output node thereof through the switch. A current steering path draws from the bitline current path a current when enabled by the command signal so that the load transistor establishes a desired voltage on the output node.

Sense amplifier for reading a cell of a non-volatile memory device

A reading circuit for nonvolatile memory cells, including a current-to-voltage converter, having an array load, connected to a memory cell, and a reference load connected to a reference generator. The array load and the reference load include PMOS transistors presenting an array shape factor (W/L),and, respectively, a reference shape factor (W/L),. The reading circuit further includes a charge pump that supplies a biasing voltage to a gate terminal of the memory cell. The biasing voltage is proportional to and higher than a supply voltage V,. The ratio between the array shape factor (W/L),and the reference shape factor (W/L),is a non-integer.

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Michele La Placa