Methods and apparatuses having a voltage generator with an adjustable voltage drop for representing a voltage drop of a memory cell and/or a current mirror circuit and replica circuit

摘要

Apparatus and methods utilize a replica circuit to generate a voltage for programming of a memory cell, such as a memory cell of a phase-change memory (PCM). Current passing through a circuit including the memory cell to be programmed is mirrored in a scaled or unscaled manner, and provided as an input to the replica circuit. The replica circuit represents voltage drops that should be encountered when programming the memory cell. An input voltage is also provided to the replica circuit, which affects the voltage drop within the replica circuit that represents the voltage drop of the cell. The voltage drop across the replica circuit can then be mirrored and provided to bias the circuit including the memory cell.

主权项

1. An apparatus comprising:
a memory cell of an array, wherein the cell is configured to store data in at least one of a plurality of states; and a voltage generator configured to generate a programming voltage for programming the cell, wherein the voltage generator is configured to represent voltage drops encountered when programming the cell of the array, wherein the represented voltage drops include an adjustable voltage drop for representing the voltage drop of the cell; wherein the array includes a path for the cell, wherein the path includes a modulator, a column decoder, a row decoder, a bit line, and at least a portion of a word line, wherein the cell is accessed via activation of the column decoder and the row decoder; wherein the voltage generator comprises:
a current mirroring circuit configured to mirror a current flowing through the path to generate a mirrored current; anda replica circuit comprising one or more resistances configured to be biased by the mirrored current, wherein the replica circuit is configured to generate a replica voltage as a sum of the voltage drops across the one or more resistances and the adjustable voltage drop, wherein the replica voltage is associated with the programming voltage for programming the cell.