Circuit for identifying a memory cell having erroneous data stored therein
AssigneeSGS-Thomson Microelectronics S.A.
InventorsCarla Golla, Silvia Padoan, Luigi Pascucci
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Abstract
A circuit for selectively programming a single bit in non-volatile memory is disclosed. The circuit consists of at least one comparator, at least one transistor, and at least one logic gate for each elementary memory in the memory word. In operation, the circuit allows for individual correction of mis-programmed cells within the memory by comparing the actual contents of the memory with the desired contents. If the actual contents does not match the desired contents, that individual cell is re-programmed.
Claims18
A circuit for identifying a memory cell having stored therein an incorrect data value, comprising:
- a device operable to read said stored data value after a write cycle;
- a comparator having a first input coupled to said device and operable to receive said stored data value, having a second input operable to receive a correct value data that was to be stored in said cell during said write cycle, and having a pair of outputs, said comparator operable to generate a first signal on a first of said outputs when said stored data value is unequal to said correct data value and a second signal on said second output in response to said first signal and when said correct data value equals a programmed value.
A circuit for identifying a memory cell having stored therein an erroneously unprogrammed data value, comprising:
- a read device having an input coupled to said memory cell and having an output;
- a first signal line that carries a proper data value that was provided to said memory cell for storage;
- a second signal line that carries a first signal level if said stored data value equals said proper data value and a second signal level if said stored data value does not equal said proper data value;
- a third signal line that carries a third level if said stored data value does not equal said proper data value and said stored data value equals an unprogrammed value;
- and
- a comparator having a first input coupled to said output of said read device, a second input coupled to said first signal line, a first output coupled to said second signal line, and a second output coupled to said third signal line.
A method for identifying an erroneous content of a memory cell after writing a data value to said memory cell, comprising:
- reading said content;
- comparing said content with said data value;
- generating a first signal if said content is unequal to said data value;
- and
- generating a second signal if said content is unequal to said data value and if said content should equal a programmed data value.
A circuit for single-bit programming a memory word stored in a plurality of elementary cells, in non-volatile memory electronic devices, being of a type which comprises, for each elementary memory cell included in said memory word, at least one comparator having a first input connected to a read circuit, for reading the contents of said memory word, and a second input receiving data corresponding to a bit to be stored into said memory word,
- at least one transistor driven from a first output of the comparator to indicate a need to have said memory word re-programmed, and
- at least one logic gate incorporated to the comparator to produce, at a second output, a signal enabling an n-th cell in said memory word whose programming has been found incorrect by the comparator to be re-programmed.
Dependencies are inferred from the claim text.