Abstract:
A charge pump circuit, connected between a first voltage reference and an output terminal, comprises at least two stages comprising an elementary charge pump circuit connected between said first voltage reference and said output terminal, and adjustment circuitry connected between said output terminal and respective control terminals of said at least two stages. This circuitry is arranged to select for actuation an appropriate combination of these elementary stages according to the current absorbed from a load connected to the output terminal.
Abstract:
Described herein is a nonvolatile memory comprising a memory array organized according to global word lines and local word lines; a global row decoder; a local row decoder; a first supply stage for supplying the global row decoder; and a second supply stage for supplying the local row decoder; and a third supply stage for biasing the drain and source terminals of the memory cells of the memory array. Each of the supply stages comprises a respective resistive divider formed by a plurality of series-connected resistors, and a plurality of pass-gate CMOS switches each connected in parallel to a respective resistor. The nonvolatile memory further comprises a control circuit for controlling the pass-gate CMOS switches of the supply stages, and a switching circuit for selectively connecting the supply input of the control circuit to the output of the second supply stage during reading and programming of the memory, and to the output of the third supply stage during erasing of the memory.
Abstract:
An analog-to-digital conversion method and device for a multilevel non-volatile memory devicethat 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 nullbit-layersnull, 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.
Abstract:
Described herein is a method for constructing a multipurpose error-control code for multilevel memory cells operating with a variable number of storage levels, in particular for memory cells the storage levels of which can assume the values of the set nullba1, baaa2, . . . , ba1a2. . . ahnull, with b, a1, . . . , ah positive integers; the error-control code encoding information words, formed by k q-ary symbols, i.e., belonging to an alphabet containing q different symbols, with qnullnullba1, ba1a2, . . . , ba1a2ahnull, in corresponding code words formed by n q-ary symbols, with qnullba1a2ah, and having an error-correction capacity t, each code word being generated through an operation of multiplication between the corresponding information word and a generating matrix. The construction method comprises the steps of: acquiring the values of k, t, ba1, ba1a2, . . . , ba1a2. . .ah, which constitute the design specifications of said error-control code; calculating, as a function of qnullba1, k and t, the minimum value of n such that the Hamming limit is satisfied; calculating the maximum values {circumflex over (n)} and {circumflex over (k)} respectively of n and k that satisfy the Hamming limit for qnullba1, t and ({circumflex over (n)}-{circumflex over (k)})null(n-k); determining, as a function of t, the generating matrix of the abbreviated error-control code (n-k) on the finite-element field GF(ba1); constructing binary polynomial representations of the finite-element fields GF(ba1) GF(ba1a2), . . . , GF(ba1a2. . . ah); identifying, using the aforesaid exponential representations, the elements of the finite-element field GF(ba1a2ah), which are isomorphic to the elements of the finite-element fields GF(ba1), GF(ba1a2), . . . , GF(ba1a2. . . ah-1); establishing biunique correspondences between the elements of the finite-element fields GF(ba1), GF(ba1a2), . . . , GF(ba1a2. . . ah1) and the elements of the finite-element field GF(ba1a2ah) that are isomorphic to them; and replacing each of the elements of said generating matrix with the corresponding isomorphic element of the finite-element field GF(ba1a2. . . ah), thus obtaining a multipurpose generating matrix defining, together with the aforesaid biunique correspondences, a multipurpose error-control code that can be used with memory cells the storage levels of which can assume the values of the set nullba1, ba1a2, . . . , ba1a2. . . ahnullnull.
Abstract:
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.