Apparatus and method for sensing multi-level cell data

A multi-level sensing method of a non-volatile memory, the multi-level sensing method comprising:

• performing a first comparison and amplification operation on a first reference voltage and a read data of a bit line to generate a first output;
• selecting one of a second reference voltage and a third reference voltage as a fourth reference voltage according to a logic level of the first output;
• performing a second comparison and amplification operation on the fourth reference voltage and the read data of the bit line to generate a second output;
• and
• decoding the first and second outputs to output a sensing data.

A sensing apparatus of a phase change memory, the sensing apparatus comprising:

• a data driver configured to be selectively turned on for connection to a bit line of the phase change memory and drive a read data of the bit line in the turned-on state;
• a first sense amplifier configured to compare the read data transferred through the bit line with a first reference voltage and amplify a comparison result to generate a first output, after the data driver is turned on;
• a reference voltage selector configured to select one of a second reference voltage and a third reference voltage as a fourth reference voltage according to a logic level of the first output;
• a second sense amplifier configured to compare the sensing voltage, the fourth reference voltage, and the read data of the bit line and amplify a comparison result to generate a second output;
• and
• a decoder configured to decode the first and second outputs to output a sensing data.

A sensing method of a phase change memory, the sensing method comprising:

• selecting and precharging a bit line;
• driving read data of the bit line after the precharging is completed;
• enabling a first sense amplifier to performing a comparison and amplification operation on a first reference voltage and the read data of the bit line to generate a first output;
• selecting one of a second reference voltage and a third reference voltage as a fourth reference voltage according to a logic level of the first output;
• enabling a second sense amplifier to perform a comparison and amplification operation on the reference voltage and the read data loaded on the bit line to generate a second output;
• and
• decoding the first and second outputs to output a sensing data.