摘要:
A circuit device structured to enable a hierarchic form of row decoding in semiconductor memory devices of the non-volatile type and including a matrix of memory cells with sectors organized into columns, wherein each sector has a group of local word lines individually connected to a main word line running through all of the matrix sectors which have rows in common is presented. The device includes a PMOS first transistor having conduction terminals connected respectively to the main word line and the local word line, an NMOS second transistor having conduction terminals connected respectively to the local word line and the main word line, and a PMOS third transistor having conduction terminals connected respectively to the main word line and the local word line. Such a third transistor is a charge transistor that reduces the charging time for the local word line.
摘要:
The memory device has hierarchical sector decoding. A plurality of groups of supply lines is provided, one for each sector row, extending parallel to the sector rows. A plurality of switching stages are each connected between a respective sector and a respective group of supply lines; the switching stages connected to sectors arranged on a same column are controlled by same control signals supplied on control lines extending parallel to the columns of sectors. For biasing the sectors, modification voltages are sent to at least one selected group of biasing lines, and control signals are sent to the switching stages connected to a selected sector column.
摘要:
The row decoder includes a predecoding stage supplied with row addresses and generating predecoding signals; and a final decoding stage, which, on the basis of the predecoding signals, drives the individual rows in the array. The predecoding stage includes a number of predecoding circuits presenting two parallel signal paths: a low-voltage path used in read mode, and a high-voltage path used in programming mode. A CMOS switch separates the two paths, is driven by high voltage via a voltage shifter in programming mode, and, being formed at predecoding level, involves no integration problems.
摘要:
A method and a circuit generate a pulse synchronization signal (ATD) for timing the memory cell read phase in semiconductor integrated electronic memory devices. The pulse signal (ATD) is generated upon detection of a change in logic state of at least one of a plurality of address input terminals of the memory cells. The method consists of duplicating the ATD signal into at least one pair of signals and propagating such signals through separate parallel timing chains at the ends of which the ATD signal is reinstated, the chains being alternately active.
摘要:
The read circuit presents a current mirror circuit including a first and second load transistor interposed between the supply line and a respective first and second output node. The first output node is connected to a cell to be read, the second output node is connected to a generating stage generating a reference current having a predetermined characteristic, and the size of the second load transistor is N times greater than the first load transistor. To permit rapid cell reading even in the presence of low supply voltage and with no initial uncertainty, an equalizing circuit presents a current balancing branch connected between the first output node and ground for generating an equalizing current presenting a ratio of 1/N with the reference current to balance the circuit before commencing the reading.
摘要:
The invention relates to a method for pinpointing erase-failed memory cells and to a relevant integrated non-volatile memory device, of the programmable and electrically erasable type comprising a sectored array of memory cells arranged in rows and columns, with at least one row-decoding circuit portion per sector being supplied positive and negative voltages. This method becomes operative upon a negative erase algorithm issue, and comprises the following steps: forcing the read condition of a sector that has not been completely erased; scanning the rows of said sector to check for the presence of a spurious current indicating a failed state; finding the failed row and electrically isolating it for re-addressing the same to a redundant row provided in the same sector.
摘要:
Described herein is an erase method for an electrically erasable nonvolatile memory device, in particular an EEPROM-FLASH nonvolatile memory device, comprising a memory array formed by a plurality of memory cells arranged in rows and columns and grouped in sectors each formed by a plurality of subsectors, which are in turn formed by one or more rows. Erase of the memory array is performed by sectors and for each sector envisages applying an erase pulse to the gate terminals of all the memory cells of the sector, verifying erase of the memory cells of each subsector, and applying a further erase pulse to the gate terminals of the memory cells of only the subsectors that are not completely erased.
摘要:
The circuit for generating reference voltages for reading a multilevel memory cell includes the following: a first memory cell and a second memory cell respectively having a first reference programming level and a second reference programming level; a first reference circuit and a second reference circuit respectively connected to said first and said second memory cells and having respective output terminals which respectively supply a first reference voltage and a second reference voltage; and a voltage divider having a first connection node and a second connection node respectively connected to the output terminals of the first reference circuit and of the second reference circuit to receive, respectively, the first reference voltage and the second reference voltage, and a plurality of intermediate nodes supplying respective third reference voltages at equal distances apart.
摘要:
A semiconductor memory such as a flash memory, which comprises at least one two-dimensional array of memory cells with a plurality of rows and columns of memory cells grouped in a plurality of packets. The memory cells belonging to the columns of each packet are formed in a respective semiconductor region with a first type of conductivity, this region being distinct from the semiconductor regions with the first type of conductivity in which the memory cells belonging to the columns of the remaining packets are formed. The semiconductor regions with the first type of conductivity divide the set of memory cells belonging to each row into a plurality of subsets of memory cells that constitute elemental memory units which can be modified individually. Thus memory units of very small dimensions can be erased individually, without excessive overhead in terms of area.
摘要:
The row decoder includes, for each word line of the memory, a respective biasing circuit receiving at the input a row selection signal switching, in preset operating conditions, between a supply voltage and a ground voltage and supplying at the output a biasing signal for the respective word line switching between a first operating voltage, in turn switching at least between the supply voltage and a programming voltage higher than the supply voltage, and a second operating voltage, in turn switching at least between the ground voltage and an erase voltage lower than the ground voltage. Each biasing circuit includes a level translator circuit receiving at the input the row selection signal and supplying as output a control signal switching between the first and the second operating voltages and an output driver circuit receiving as input the control signal and supplying at the output the biasing signal.