Stmicroelectronics S.r.l.

Stmicroelectronics International N.v.

Alma Mater Studiorum-universitá Di Bologna

Marcella Carissimi

Marco Pasotti

Laura Capecchi

Fabio Enrico Carlo Disegni

Emanuela Calvetti

Vikas Rana

Riccardo Zurla

Chantal Auricchio

Cesare Torti

Fabio De Santis

Antonio Gnudi

Eleonora Franchi Scarselli

Alessio Antolini

Andrea Lico

Alessandro Tomasoni

Daniele Lo Iacono

Rajat Kulshrestha

Roberto Antonio Canegallo

Davide Manfre′

Federico Goller

Davide Lena

Abhishek Lal

Vivek Tyagi

Davide Manfre'

BharathManoj Manda

Stefano Zanchi

Paolo Romele

Alessandro Cabrini

Riccardo Vignali

Riccardo Zurla, Jr

An in-memory computation device includes a word line activation circuit that receives an input signal indicative of input values and provides activation signals each as a function of the input value. The in-memory computation device further includes a memory array, a biasing circuit generating a bias voltage and a digital detector. The memory array has memory cells coupled to a bit line and each to a word line. Each memory cell stores a computational weight. In response to an activation signal, a cell current flows through each memory cell as a function of the bias voltage, the activation signal and the computational weight. A bit line current flows through the bit line as a function of a summation of the cell currents. The digital detector is coupled to the bit line, samples the bit line current and, in response, provides an output signal.

In-memory computation device having improved drift compensation

The present disclosure is directed to a method for storing information in a coded manner in non-volatile memory cells. The method includes providing a group of non-volatile memory cells of non volatile memory. The memory cell is of the type in which a stored logic state, which can be logic high or logic low, can be changed through application of a current to the cell and the state in the memory cell is read by reading a current provided by the cell. The group of non-volatile memory cells include a determined number of non-volatile memory cells which is greater than two. The group of non-volatile memory cells store a codeword formed by the values of said stored states of the cells of the group taken according to a given order. Given a set of codewords obtainable by the stored values in the determined number of non-volatile memory cells in a group, the method includes storing the information in at least two subsets of said set of codewords comprising each at least a codeword. Each codeword in a same subset has a same Hamming weight. Each codeword belonging to one subset has a Hamming distance equal or greater than two with respect to each codeword belonging to another subset.

Method for storing information in a coded manner in non-volatile memory cells, decoding method and non-volatile memory

In embodiments, a voltage regulator has an input node to receive an input voltage and an output node. The voltage regulator has a charge pump circuit that receives a boosting control signal to boost the input voltage based on the boosting control signal. The voltage regulator further has a feedback regulation circuit configured to receive the output voltage and to provide a first operation control signal and a second operation control signal as a function of the output voltage; a phase control circuit configured to receive the first operation control signal and to provide the boosting control signal as a function of the first operation control signal; and a filter coupled to the output node, configured to receive the second operation control signal and configured to inject to or sink from the output node a charge that is a function of the second operation control signal.

Voltage regulator comprising a charge pump circuit

A voltage regulator receives a reference voltage and generates a regulated voltage using a MOSFET having a gate terminal configured to receive a control voltage. A charge pump receives the regulated voltage and generates a charge pump voltage in response to an enable signal and a clock signal generated in response to the enable signal. The voltage regulator further includes a first switched capacitor circuit coupled to the gate terminal and configured to selectively charge a first capacitor with a first current and impose a first voltage drop on the control voltage in response to assertion of the enable signal. The voltage regulator also includes a second switched capacitor circuit coupled to the gate terminal and configured to selectively charge a second capacitor with a second current and impose a second voltage drop on the control voltage in response to one logic state of the clock signal.

Voltage regulator circuit for a switching circuit load

An in-memory computation circuit includes a memory array with memory cells arranged in a matrix in rows and columns. Groups of memory cells store computational weights for an in-memory compute (IMC) operation that is performed with a first multiply and accumulate (MAC) elaboration to produce a first analog signal and a second MAC elaboration to produce a second analog signal. An analog-to-digital converter circuit operates to: increment a count value in a counter circuit in response to the first analog signal; convert the count value in the counter circuit to a negated count value; and increment the count value in the counter circuit starting from the negated count value in response to the second analog signal.

In-memory computation system with built-in subtraction mode for handling matrix vector multiplication of signed feature data and signed computational weight data

The present disclosure is directed to a sense amplifier architecture for a memory device having a plurality of memory cells. Groups of non-volatile memory cells store respective codewords formed by stored logic states, logic high or logic low, of the memory cells of the group. The sense amplifier architecture has a plurality of sense amplifier reading branches, each sense amplifier reading branch coupled to a respective memory cell and configured to provide an output signal, which is indicative of a cell current flowing through the same memory cell; a comparison stage, to perform a comparison between the cell currents of memory cells of a group; and a logic stage, to determine, based on comparison results provided by the comparison stage, a read codeword corresponding to the group of memory cells. Information may be stored in different subsets of codewords, the sense amplifier architecture in this case having a subset definition circuit, to allow a preliminary determination of the subset to which a codeword to be read belongs to, based on reference signals.

Sense amplifier architecture for a non-volatile memory storing coded information

An in-memory computation (IMC) circuit includes a memory array formed by memory cells arranged in row-by-column matrix. Computational weights for an IMC operation are stored in the memory cells. Each column includes a bit line connected to the memory cells. A switching circuit is connected between each bit line and a corresponding column output. The switching circuit is controlled to turn on to generate the analog signal dependent on the computational weight and for a time duration controlled by the coefficient data signal. A column combining circuit combines (by addition and/or subtraction) and integrates analog signals at the column outputs of the biasing circuits. The addition/subtraction is dependent on one or more a sign of the coefficient data and a sign of the computational weight and may further implement a binary weighting function.

Signed and binary weighted computation for an in-memory computation system

A circuit includes a memory array with memory cells arranged in a matrix of rows and columns, where each row includes a word line connected to the memory cells of the row, and each column includes a bit line connected to the memory cells of the column. Computational weights for an in-memory compute operation (IMCO) are stored in the memory cells. A word line control circuit simultaneously actuates word lines in response to input signals providing coefficient data for the IMCO by applying word line signal pulses. A column processing circuit connected to the bit lines processes analog signals developed on the bit lines in response to the simultaneous actuation of the word lines to generate multiply and accumulate output signals for the IMCO. Pulse widths of the signal pulses are modulated to compensate for cell drift. The IMCO further handles positive/negative calculation for the coefficient data and computational weights.

In-memory computation system with drift compensation circuit

An in-memory computation (IMC) circuit includes a memory array formed by memory cells arranged in row-by-column matrix. Computational weights for an IMC operation are stored in the memory cells. Each column includes a bit line connected to the memory cells. A biasing circuit is connected between each bit line and a corresponding column output. A column combining circuit combines and integrates analog signals at the column outputs of the biasing circuits. Each biasing circuit operates to apply a fixed reference voltage level to its bit line. Each biasing circuit further includes a switching circuit that is controlled to turn on for a time duration controlled by asps comparison of a coefficient data signal to a ramp signal to generate the analog signal dependent on the computational weight. The ramp signal is generated using a reference current derived from a reference memory cell.

Compensated analog computation for an in-memory computation system

A memory device includes programmable memory cells and a programming circuit for programming a selected memory cell to a target logic state by applying one or more programming current pulses. A temperature sensor operates to sense a temperature of the memory device. A reading circuit reads a current logic state of the selected memory cell after a predetermined programming current pulse of the programming current pulses. The reading circuit includes a sensing circuit that senses a current logic state of the selected memory cell according to a comparison between a reading electric current depending on the current logic state of the selected memory cell and a reference current. An adjusting circuit adjusts one or the other of the reading electric current and the reference electric current to be provided to the sensing circuit according to the temperature of the memory device.

Memory device

An embodiment memory device comprises a plurality of memory cells, each exhibiting a transconductance depending on a value of a stored bit, a plurality of bit lines associated with respective groups of memory cells, each bit line configured to flow a respective electric current indicative of the bit stored in a selected memory cell of the respective group of memory cells, and a computing circuit providing an output electric quantity indicative of a linear combination of a plurality of input electric quantities. The computing circuit comprises a biasing stage configured to bias each bit line with a respective input electric quantity, the electric current flowing through each bit line based on a product of the respective input electric quantity and the transconductance of the selected memory cell, and a combining stage for combining the electric currents flowing through the plurality of bit lines thereby obtaining the output electric quantity.

Memory device and method for in-memory computing

A system and method for operating a memory cell is provided. A non-volatile memory storage device includes an array of memory cells of differential or single-ended type. In an embodiment, a regulator is coupled to a sense amplifier. The regulator is configured to generate a voltage to gate terminals of one or two transistors of the sense amplifier. In the differential type, the voltage is generated such that the first bias current and the second bias current have a current value equal to the sum of a maximum current flowing in a memory cell being in a RESET state and a fixed current. In the single-ended type, the regulated voltage is generated such that the first bias current and the second bias current have a current value equal to the sum of a fixed current and the reference current generated by the reference current source across temperature.

Regulator of a sense amplifier

An embodiment non-volatile memory device includes an array of memory cells in rows and columns; a plurality of local bitlines, the memory cells of each column being coupled to a corresponding local bitline; a plurality of main bitlines, each main bitline being coupleable to a corresponding subset of local bitlines; a plurality of program driver circuits, each having a corresponding output node and injecting a programming current in the corresponding output node, each output node coupleable to a corresponding subset of main bitlines. Each program driver circuit further includes a corresponding limiter circuit that is electrically coupled, for each main bitline of the corresponding subset, to a corresponding sense node whose voltage depends, during writing, on the voltage on the corresponding main bitline. Each limiter circuit turns off the corresponding programming current, in case the voltage on any of the corresponding sense nodes overcomes a reference voltage.

Non-volatile memory device with a program driver circuit including a voltage limiter

A non-volatile memory device includes a memory array, a reading circuit, a column decoder stage, and a read supply voltage generator. The column decoder stage includes selectable bitlines and selection switches. A read supply voltage generator includes a voltage regulation circuit and a dummy column decoder coupled to an output of the voltage regulation circuit and having electrical characteristics correlated to the selected read path. The voltage regulation circuit is configured to receive a first electrical quantity correlated to a desired voltage value on the selected bitline and a second electrical quantity correlated to a desired current value for the selected bitline and to generate a regulated read supply voltage for the column decoder stage.

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Treviolo, Italy

Marcella Carissimi