Sgs-thomson Microelectronics S.r.l.

Stmicroelectronics S.r.l.

Stmicroelectronics Gmbh

Alessandro Manstretta

Guido Torelli

Cristiano Calligaro

Roberto Gastaldi

Vincenzo Daniele

Andrea Pierin

Nicola Telecco

Rino Micheloni

Paolo Rolandi

Giovanni Campardo

Paolo Giuseppe Cappelletti

Osama Khouri

Alberto Modelli

Emilio Yero

A reading circuit for semiconductor non-volatile memories connected to at least one selected cell and at least one reference cell, the circuit including current/voltage conversion circuits receiving a first current flowing through the selected cell and a second current flowing through the reference cell and providing respectively on a first circuit node a first selected cell voltage and on a second node a second reference cell voltage, at least one differential amplifier connected at the input of the first and the second nodes and having an output terminal to provide a logic signal correlated to the selected cell information, a first voltage-controlled discharge switch circuit connected to the first node and to a voltage reference, a second switch circuit connected to the second node and the voltage reference, and first and second voltage comparator circuits receiving the first selected cell voltage and the second reference cell voltage.

Reading circuit for semiconductor non-volatile memories

A non-volatile memory device with configurable row redundancy includes a non-volatile memory having a matrix of memory cells and a matrix of redundant memory cells, both organized into rows and columns. The memory device also includes row and column decoding circuits; read and modify circuits for reading and modifying data stored in the memory cells; and at least one associative memory matrix, also organized into rows and columns, able to store the addresses of faulty rows, and control circuits for controlling the associative memory matrix. The memory device further includes a circuit for recognizing and comparing selected row addresses with faulty row addresses contained in the associative memory matrix, such as to produce de-selection of the faulty row and selection of the corresponding redundant cell row in the event of a valid recognition; and a configuration register, also comprising a matrix of non-volatile memory cells, and associated control circuits.

Non-volatile memory device with configurable row redundancy

When programming, for each programming pulse, a threshold voltage whose value is increased with respect to the previous programming pulse is applied to the gate terminal of each cell to be programmed. After an initial step, the increase of threshold voltage of the cell being programmed becomes equal to the applied gate voltage increase. In order to reduce the global programming time, keeping a small variability interval of threshold voltages associated with each level, to pass from a threshold level to a following one, each cell to be programmed is supplied with a plurality of consecutive pulses without verify, until it is immediately below the voltage level to be programmed, and then a verify step is performed, followed by subsequent programming and verify steps until the cell to be programmed reaches the desired threshold value.

Method for programming multi-level non-volatile memories by controlling the gate voltage

A non-volatile memory device is organized with memory cells that are arranged by row and by column. The memory device includes a sector of matrix cells, row decoders and column decoders suitable to decode address signals and to activate respectively the rows or said columns, at least a sector of redundancy cells such that it is possible to substitute a row of the sector of matrix cells with a row of the sector of redundancy cells. The non-volatile memory device comprises a local column decoder for the matrix sector and a local column decoder for the redundancy sector. The local column decoders are controlled by external signals so that the row of the redundancy sector is activated simultaneously with the row of the matrix sector.

Non-volatile memory device with row redundancy

A monolithically integrated selector for electrically programmable memory cell devices can be switched at an output terminal (OUT) between a high voltage (HV) and a low voltage (LV). It comprises a leg (N,, N,) of fast ground discharge (GND) from the output terminal, a discharge control leg (P,, N,, N,) driving the selector switching through a phase generator (PHG).

Monolithically integrated selector for electrically programmable memory cell devices

A selector switch monolithically integrated to a CMOS technology circuit for electrically programmable memory cell devices having at least first and second input terminals for coupling to first and second voltage generators (HV and LV), respectively, and an output terminal. First and second field-effect selection transistors are respectively connected, via first and second terminals, between the first input terminal and the output terminal and between the second input terminal and the output terminal. These transistors are driven through control terminals at non-overlapping phases and have body terminals connected at a body circuit node which is coupled to the first and second voltage generators through a bias circuit block effective to bias the node to the higher of the instant voltages generated by the first and second generators.

The invention relates to a driving circuit for row decoding which is also useful in non-volatile memory devices of the multi-level Flash type and the multi-level EPROM type and allows the overall capacitive loads as seen from the program voltage generator and the read/verify voltage generator, to be drastically reduced without involving segmentation of the decoding circuit.

High voltage driver circuit for a decoding circuit in multilevel

In a storage device of the multi-level type, comprising a plurality of memory cells addressable through an address input each cell being adapted for storing more than one binary information element in a MOS transistor which has a control gate, and a floating gate for storing electrons to modify the threshold voltage of the transistor, and comprising a circuit enabling a Direct Memory Access (DMA) mode for directly accessing the memory cells from outside the device, the memory cells are programmed in the direct memory access mode by controlling, from outside the device, the amount of charge stored into the floating gate of each transistor.

Multilevel non-volatile memory devices

A staircase adaptive voltage generator circuit comprising a first capacitor connected between a first voltage reference and an output operational amplifier, through first and second switches, respectively. The terminals of the capacitor are also connected to a second voltage reference through third and fourth switches, respectively. A second capacitor, in series with a fifth switch, is connected in parallel to the first capacitor.

Staircase adaptive voltage generator circuit

Reading circuit for multilevel non-volatile memory cell devices having, for each cell to be read, a selection line with which is associated a load and a decoupling and control stage with a feedback loop which stabilizes the voltage on a circuit node of the selection line. To this node are connected a current replica circuit which are controlled by the feedback loop. These include loads and circuit elements homologous to those associated with the selection line of the memory cell and have an output interface circuit for connection to current comparator circuit.

Reading circuit for multilevel non volatile memory cell devices

A page-mode semiconductor memory device comprises a matrix of memory cells arranged in rows and columns, each row forming a memory page of the memory device and comprising at least one group of memory cells, memory page selection means for selecting a row of the matrix, and a plurality of sensing circuits each one associated with a respective column of the matrix. The memory cells are multiple-level memory cells which can be programmed in a plurality of c=2b(b&gt;1) programming states to store b information bits, and the sensing circuits are serial-dichotomic sensing circuits capable of determining, in a number b of consecutive approximation steps, the b information bits stored in the memory cells, at each step one of said b information bits being determined, said at least one group of memory cells of a row forming a number b of memory words of a memory page.

Page-mode memory device with multiple-level memory cells

A method for sensing multiple-levels non-volatile memory cells which can take one programming level among a plurality of m=2.sup.n (n&gt;=Z) different programming levels, provides for biasing a memory cell to be sensed in a predetermined condition, so that the memory cell sinks a cell current with a value belonging to a discrete set of m distinct cell current values, each cell current value corresponding to one of said programming levels. The sensing method also provides for: simultaneously comparing the cell current with a prescribed number of reference currents having values comprised between a minimum value and a maximum value of said discrete set of m cell current values and dividing said discrete set of m cell current values in a plurality of sub-sets of cell current values, for determining the sub-set of cell current values to which the cell current belongs; repeating step (a) for the sub-set of cell current values to which the cell current belongs, until the sub-set of cell current values to which the cell current belongs comprises only one cell current value, which is the value of the current of the memory cell to be sensed.

Parallel-dichotomic serial sensing method for sensing multiple-level

A serial dichotomic method for sensing multiple-level non-volatile memory cells which can take one of m=2.sup.n (n&gt;=2) different programming levels, provides for biasing a memory cell to be sensed in a predetermined condition, so that the memory cell sinks a cell current with a value belonging to a plurality of m distinct cell current values, and for: a) comparing the cell current with a reference current which has a value comprised between a minimum value and a maximum value of said plurality of m cell current values, thus dividing said plurality of cell current values into two sub-pluralities of cell current values, and determining the sub-plurality of cell current values to which the cell current belongs; b) repeating the step a) until the sub-plurality of cell current values to which the cell current belongs comprises only one cell current value, which is the value for the current of the memory cell to be sensed.

Serial dichotomic method for sensing multiple-level non-volatile memory

A sensing circuit for serial dichotomic sensing of multiple-level memory cells which can take one programming level among a plurality of m=2.sup.n (n&gt;=2) different programming levels, comprises biasing means for biasing a memory cell to be sensed in a predetermined condition, so that the memory cell sinks a cell current with a value belonging to a plurality of m distinct cell current values, each cell current value corresponding to one of the programming levels, a current comparator for comparing the cell current with a reference current generated by a variable reference current generator, and a successive approximation register supplied with an output signal of the current comparator and controlling the variable reference current generator. The variable reference current generator comprises an offset current generator permanently coupled to the current comparator, and m-2 distinct current generators, independently activatable by the successive approximation register, each one generating a current equal to a respective one of the plurality of cell current values.

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Broni, Italy

Alessandro Manstretta