Reference voltage generating apparatus for use in a ferroelectric random access memory (FRAM) and a driving method therefor

An apparatus for generating a reference voltage to read data from a ferroelectric memory cell including a ferroelectric capacitor and a transistor, the apparatus comprising:

• a reference cell array having a plurality of reference cells each of the plurality of reference cells including a ferroelectric capacitor and a transistor;
• a plurality of reference word lines respectively connected to the transistors in the plurality of reference cells;
• a plurality of bit lines respectively connected to the plurality of reference cells;
• a plurality of reference plate lines respectively connected to the ferroelectric capacitors in the plurality of reference cells;
• and
• a reference voltage generating circuit for re-storing, in at least one of the plurality of reference cells, data equal to data stored in the at least one of the plurality of reference cells, in response to a first control signal, and for generating a reference voltage in at least one of the re-stored reference cells in response to a second control signal, and for comparing the reference voltage with a voltage corresponding to data stored in the ferroelectric memory cell and for reading the data stored in the ferroelectric memory cell.

A method of generating a stable reference voltage in a reference cell to read data from a ferroelectric memory cell, comprising:

• storing second data in the reference cell, wherein the second data is equal to first data previously stored in the reference cell;
• generating the stable reference voltage in the reference cell with the second data;
• sensing a voltage of the ferroelectric memory cell;
• comparing the voltage of the ferroelectric memory cell with the stable reference voltage;
• and
• reading the data in the ferroelectric memory cell.

A method of driving a reference voltage generating apparatus for supplying a reference voltage to read data from a ferroelectric memory cell including a ferroelectric capacitor and an access transistor, the method comprising:

• re-storing, in a reference cell, data equal to data stored in the reference cell, in response to a first control signal;
• and
• generating a reference voltage, in the re-stored reference cell, in response to a second control signal, to compare the reference voltage with a voltage corresponding to data stored in the ferroelectric memory cell and to read the data stored in the ferroelectric memory cell,
• wherein the step of re-storing the data in the reference cell is performed before enabling an excitation control signal in which data stored in the memory cell is excited to a bit line connected to the memory cell.

A method of driving a reference voltage generating apparatus for supplying a reference voltage to read data from a ferroelectric memory cell including a ferroelectric capacitor and an access transistor, the method comprising:

• re-storing, in a reference cell, data equal to data stored in the reference cell, in response to a first control signal;
• and
• generating a reference voltage, in the re-stored reference cell, in response to a second control signal, to compare the reference voltage with a voltage corresponding to data stored in the ferroelectric memory cell and to read the data stored in the ferroelectric memory cell,
• wherein the reference cell comprises:
• a ferroelectric capacitor and an access transistor, the reference voltage is generated in a non-switching area of the ferroelectric capacitor in the reference cell.