Memory with a core-based virtual ground and dynamic reference sensing scheme
A core-based multi-bit memory ( 400 ) having a dual-bit dynamic referencing architecture ( 408, 410 ) fabricated on the memory core ( 401 ). A first reference array ( 408 ) and a second reference array ( 410 ) are fabricated on the memory core ( 401 ) such that a reference cell pair ( 185 ) comprising one cell ( 182 ) of the first reference array ( 408 ) and a corresponding cell ( 184 ) of the second reference array ( 410 ) are read and averaged to provide a reference voltage for reading a data array(s).
1. A method associated with a multi-bit memory cell having a redundancy array located proximate or adjacent to groups of data sectors, comprising,
pre-charging first and second reference arrays each comprised of a plurality of reference cells wherein a program order for precharging the reference cells in the first and second reference arrays is from a last reference cell in the first reference array and a first reference cell in the second reference array to a first reference cell in the first reference array and a last reference cell in the second reference array to reduce transmitting effect prior to averaging voltage levels associated therewith; and
averaging a first bit value of a first reference cell of the first reference array with a second bit value of a second reference cell of the second reference array to generate a reference voltage for use with a data cell read operation.
2. The method of claim 1 , further comprising cycling the first bit of the first reference cell so that the first bit ages with a corresponding data bit.
3. The method of claim 1 , further comprising comparing the reference voltage value with a voltage value obtained from a data bit to determine if the data bit is in a programmed state or an unprogrammed state.
4. The method of claim 1 , further comprising amplifiers that amplify voltages obtained from the first reference cell and the second reference cell.
5. The method of claim 1 , the first and second reference arrays are fabricated adjacent to each other.
6. The method of claim 1 , further comprising cycling the second bit of the second reference cell so that the second bit ages with the corresponding data bit.
7. The method of claim 1 , wherein the averaging of the first bit value and the second bit value is performed by a voltage divider.
8. The method of claim 1 , further comprising controlling a plurality of select gates that enable reading, writing and erasing of reference cells associated with the first and second reference arrays.
9. The method of claim 1 , the first bit and the second bit are associated with the multi-bit memory cell in a wordline, the first bit and the second bit utilized during reading of bits in the wordline.
10. The method of claim 1 , the first and second reference arrays are located centrally of the groups of data sectors.
11. The method of claim 1 , further comprising reading bits associated with the groups of data sectors in an interleaved manner with bits associated with the first and second reference arrays.
12. The method of claim 1 , further comprising controlling a plurality of switches that connect bitlines associated with reference cells of the first and second reference arrays to power (VDD) or ground (GND) to facilitate a read operation.
13. The method of claim 1 , further comprising:
summing currents from the first bit and the second bit to produce a resulting current; and
converting the resulting current to a summed voltage, wherein the summed voltage is used to produce the reference voltage.