Abstract:
A non volatile memory device based on the realization of two distinct orders of main wordlines and bitlines, distinguishing a first order as main read wordlines (MWLR) and main read bitlines (MBLR) and a second order as main program wordlines (MWLP) and main program bitlines (MBLP), to each pair of main lines of which are associated a certain number of local lines, for example four lines, in each sector of subdivision of the array of memory cells, according to the criteria that are normally used in the so called hierarchical decoding structures of a memory whose array of elementary memory cells is subdivided in banks and/or sectors. Distinct decoders are associated to the two distinct orders of main wordlines and of main bitlines, the relative inputs of which are two address buses for reading and programming/erasing operations, respectively. A first address bus (RADD) coming from the address input pads of the device, through commonly used circuits, realizes a path for the read addresses to be input to main read wordlines decoders and to main read bitlines decoders. The input of the decoders of the main program wordlines and of the main program bitlines is, on the contrary, provided by an internal bus (PADD), generated by controllers of program and erase operations that control all the verification and load operations of data to be programmed.
Abstract:
The method for timing reading of a memory cell envisages supplying the memory cell (10) with a constant current (I) by means of a first capacitive element (23), integrating said current (I) in a time interval (Δt), and controlling the duration of the time interval (Δt) in such a way as to compensate for any deviations in the current (I) from a nominal value. In particular, a reference current (I R ) is supplied to a reference cell (101) by means of a second capacitive element (122); next, a first voltage (Var) present on the second capacitive element (122) is measured; finally, the memory cell (10) is deactivated when the first voltage (Var) is equal to a second voltage (Vref), which is constant.
Abstract:
The method for reading a memory cell includes supplying the cell (30) with a first charge quantity (ΔQb) through a capacitive integration element (39) and reintegrating the first charge quantity (ΔQb) through a plurality of second charge quantities (Qa) supplied alternately and in succession to the capacitive integration element (39). In a first embodiment, the second charge quantities (Qa) are initially stored in a plurality of capacitive charge-regeneration elements (37, 38) connected alternately and in succession to the capacitive integration element (39); the second charge quantities (Qa) are then shared between the capacitive integration element (39) and the capacitive charge-regeneration elements (37, 38).
Abstract:
The multilevel memory device (1) has a memory section containing cells (2a) that can be programmed with a predetermined number of levels greater than two, i.e. a multilevel array (2), and a memory section containing cells that can be programmed with two levels, i.e. a bilevel array (3). The multilevel array (2) is used for storing high density data, for which speed and reliability of reading are not essential, for example for storing the operation code of the system including the memory device. On the other hand, the bilevel array (3) is used for storing data for which high speed and reliability of reading is essential, such as the BIOS of personal computers, and the data to be stored in a cache memory. The circuitry parts dedicated to programming, writing of test instructions, and all the functions necessary for the operation of the memory device (1), are common to both arrays.
Abstract:
The memory device (10) comprises a memory array (2) having an organisation of the type comprising global word lines (4) and local word lines (6), a global row decoder (8) addressing the global word lines (4), a local row decoder (12) addressing the local word lines (6), a global power supply stage (22) supplying the global row decoder (8), and a local power supply stage (24) supplying the local row decoder (12).
Abstract:
A voltage regulating circuit for a capacitive load, being connected between first and second terminals of a supply voltage generator (VDD,GND) and having an input terminal (IN) and an output terminal (OUT), comprises an operational amplifier (OP) having an inverting (-) input terminal connected to the input terminal (IN) of the regulating circuit and a non-inverting (+) input terminal connected to an intermediate node of a voltage divider (R1,R2) which is connected between an output node connected to the output terminal (OUT) of the regulating circuit and the second terminal (GND) of the supply voltage generator, and having an output terminal connected, for driving a first field-effect transistor (MPU), between the output node and the first terminal (VDD) of the supply voltage generator, the output terminal of the operational amplifier being further connected to the output node through a compensation network (COMP), and comprises a second field-effect transistor (MPD1) connected between the output node and the second terminal of the supply voltage generator (GND) and having its gate terminal connected to a constant voltage generating circuit means (RB,CB,MB,IB).
Abstract:
The memory device (21) has hierarchical sector decoding (24, 25). A plurality of groups of supply lines (28-32) is provided, one for each sector row, extending parallel to the sector rows. A plurality of switching stages (35) are each connected between a respective sector (15) and a respective group of supply lines (28-32); the switching stages (35) connected to sectors (15) arranged on a same column are controlled by same control signals (S0, S1) supplied on control lines (40) extending parallel to the columns of sectors. For biasing the sectors, modification voltages (NW, SB, V NEG ) are sent to at least one selected group of biasing lines (28-32), and control signals (SO, S1) are sent to the switching stages connected to a selected sector column.