Stmicroelectronics S.r.l.

Stefano Gregori

Guido Torelli

Rino Micheloni

Andrea Pierin

Osama Khouri

Miriam Sangalli

Pietro Ferrari

Dario Soltesz

Khouri Osama

Sergio Coronini

Described is an error control method for multilevel memory cells operating with a variable number of storage levels. The method includes: receiving a first information word having k input symbols each in a first base; converting the first information word into a second base by converting the input symbols into input symbols in the second base; encoding the converted first information word into a first codeword having k+n coded symbols in the second base; and writing the first codeword into the multilevel memory cells. The encoding step may include generating a generating matrix and multiplying the first information word by the generating matrix to produce the first codeword.

Multipurpose method for constructing an error-control code for multilevel memory cells operating with a variable number of storage levels, and multipurpose error-control method using said error-control code

A method for programming a nonvolatile memory cell envisages applying in succession, to the gate terminal of the memory cell, a first and a second programming pulse trains with pulse amplitude increasing in staircase fashion, in which the amplitude increment between one pulse and the next in the first programming pulse train is greater than the amplitude increment between one pulse and the next in the second programming pulse train. The programming method envisages applying, to the gate terminal of the memory cell and before the first programming pulse train, a third programming pulse train with pulse amplitude increasing in staircase fashion, in which the amplitude increment between one pulse and the next may be less than the amplitude increment in the first programming pulse train and substantially equal to the amplitude increment in the second programming pulse train, or else may be greater than the amplitude increment in the first programming pulse train.

Method for programming nonvolatile memory cells with program and verify algorithm using a staircase voltage with varying step amplitude

An analog-to-digital conversion method and device for a multilevel non-volatile memory device that includes a multilevel memory cell. The method comprises a first step of converting the most significant bits contained in the memory cell, followed by a second step of converting the least significant bits. The first step is completed within a time interval corresponding to the rise transient of the gate voltage, and the second step is initiated at the end of the transient. Also disclosed is a scheme for error control coding in multilevel Flash memories. The n bits stored in a single memory cell are organized in different &ldquo;bit-layers&rdquo;, which are independent from one another. Error correction is carried out separately for each bit-layer. The correction of any failure in a single memory cell is achieved by using a simple error control code providing single-bit correction, regardless of the number of bits stored in a single cell.

Analog-to-digital conversion method and device, in high-density multilevel non-volatile memory devices

A multilevel nonvolatile memory includes a supply line ( ) supplying a supply voltage (V ), a voltage boosting circuit ( ) supplying a boosted voltage (V ), higher than the supply voltage (V ), a boosted line ( ) connected to the voltage boosting circuit ( ) and a reading circuit ( ) including at least one comparator ( ). The comparator ( ) includes a first and a second input ( ), a first and a second output ( ), at least one amplification stage ( ) connected to the boosted line ( ), and a boosted line latch stage ( ) connected to the supply line ( ).

Small size, low consumption, multilevel nonvolatile memory

A circuit device for performing hierarchic row decoding in semiconductor memory devices of the non-volatile type, which memory devices include an array of memory cells with column-ordered sectors, wherein each sector has a respective group of local wordlines linked to a main wordline. The circuit device includes a main wordline driver provided at each main wordline, and a local decoder provided at each local wordline. This circuit device further comprises, for each main wordline, a dedicated path connected between the main wordline and the local decoders of the associated local wordlines and connected to an external terminal arranged to receive a read/program voltage, the dedicated path enabling transfer of the read/program voltage to the local decoders.

Circuit device for performing hierarchic row decoding in non-volatile memory devices

A circuit for reading a non-volatile memory cell has an output terminal for providing an output current, and a control terminal for receiving a voltage for controlling the output current. The reading circuit includes a feedback circuit which can be connected electrically to the output terminal and to the control terminal to generate the control voltage from a reference signal and from the output current. The feedback circuit also includes a current-amplification circuit having a first terminal for receiving a current-error signal derived from the reference signal and from the output current, and a second terminal for supplying an amplified current.

Circuit for reading non-volatile memories

A charge pump voltage booster circuit for generating, from a first voltage supplied at the input to the circuit, an output voltage with an absolute value that is higher than the first voltage, comprises at least one stage having a charge pass element and a charge storage capacitor with a first plate connected to an output of the charge pass element and a second plate controlled by a square-wave control signal of period varying between a reference voltage and the first voltage, supplied to the second plate of the capacitor by means of a driver circuit comprising a pull-up transistor and a pull-down transistor connected in series between the first voltage and the reference voltage. Means of overdriving at least one of the said transistors, either the pull-up transistor or the pull-down transistor, supply to the said at least one transistor a firing control voltage that has a higher absolute value than the first voltage.

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Torre d'Isola, Italy

Stefano Gregori