Decoding system capable of reducing sector select area overhead for flash memory
View Patent ↗Methods and apparatus are disclosed for erasing memory cells in a virtual ground memory core, wherein a row decoder apparatus employs a protective voltage to wordlines of a sector of cells while concurrently providing an erase voltage to selected wordlines of the same physical sector. Decoder circuitry and methods are disclosed for selecting a memory cell sector to be erased and adjacent sectors to be protected, which may be used in single bit and dual bit memory devices, and which enable column decoder circuitry to reduce the number of sector select circuits.
1. A memory device, comprising:
a physical sector comprising a plurality of core sectors organized in a virtual ground configuration;
wherein the plurality of core sectors comprise:
a plurality of memory cells;
a plurality of gate terminals coupled to at least one wordline;
a plurality of drain terminals coupled to at least one bitline;
a plurality of source terminals coupled to at least one bitline;
a decoder operatively coupled to the at least one wordline of the plurality of core sectors; and
wherein the decoder comprises a shifter, an x-dec circuit, and at least one x-dec sub circuit;
wherein the decoder is configured to maintain isolated control of the at least one wordline of the plurality of core sectors and further configured to inhibit at least one core sector by generating an inhibiting voltage to the at least one core sector within the physical sector.
2. The memory device of claim 1 , wherein the physical sector comprises 2 N core sectors and N is any positive integer or zero.
3. The memory device of claim 1 , wherein the physical sector is coupled to a decoder comprising a set of two sector select circuits shared among 2 N core sectors wherein N is any positive integer or zero.
4. The memory device of claim 1 , wherein the shifter creates a high voltage gate control signal to the x-dec circuit.
5. The memory device of claim 1 , wherein the x-dec circuit processes a gate control signal to the x-dec sub circuit.
6. The memory device of claim 1 , wherein the at least one sub circuit generates a positive high voltage from a VWL node to the at least one wordline of the plurality of core sectors or a negative high voltage from a negative voltage or a float to the at least one core sector within the physical sector.
7. The memory device of claim 1 , wherein each core sector is a density of about 1 MB.
8. The memory device of claim 1 , wherein the decoder is a row decoder that is configured to concurrently generate an erase voltage to the at least one wordline of the plurality of core sectors while generating an inhibiting voltage to the at least one core sector within the physical sector.
9. The memory device of claim 1 , further comprising a column decoder.
10. The memory device of claim 9 , wherein the column decoder comprises a set of two sector select circuits coupled to and shared among the 2 N core sectors of the physical sector, wherein N is any positive integer.
11. A method of manufacturing a memory device, comprising:
forming a physical sector comprising a plurality of core sectors;
wherein each core sector comprises:
a plurality of memory cells;
a plurality of gate terminals coupled to at least one wordline;
a plurality of drain terminals coupled to at least one bitline;
a plurality of source terminals coupled to at least one bitline;
isolating control of at least one core sector within the physical sector; and
generating an inhibiting voltage to at least one wordline of the plurality of core sectors within the physical sector by a decoder;
wherein the decoder comprises a shifter, an x-dec circuit, and at least one x-dec sub circuit.
12. The method of claim 11 , wherein isolating control of the at least one core sector comprises generating a high voltage signal and wherein the decoder is a row decoder.
13. The method of claim 11 , wherein isolating control of the at least one core sector comprises generating a positive voltage to the at least one wordline of the plurality of core sectors while concurrently generating a negative voltage to at least one core sector of the physical sector.
14. The method of claim 11 , further comprising:
forming a VWL node; and
wherein generating the inhibiting voltage comprises generating a positive high voltage from the VWL node while concurrently generating a negative high voltage from a negative voltage or a float for isolating control.
15. The method of claim 11 , wherein forming a memory device further comprises forming a column decoder.
16. The method of claim 11 , wherein forming a column decoder comprises forming a set of two sector selects and a sensing amplifier.
17. The method of claim 11 , wherein forming a physical sector comprises forming about 1000 to about 2048 bitlines and about 256 to about 512wordlines.
18. The method of claim 11 , wherein the accessing voltage is a negative voltage and the inhibiting voltage is a positive voltage.
19. A communication device, comprising:
a flash memory CPU;
the flash memory operatively coupled to the CPU and configured to transfer data to and from the CPU;
an input component for entering the data;
a display component for displaying information;
a plurality of switches;
flash memory;
a physical sector; and
a method of forming a physical sector comprising a plurality of core sectors;
wherein each core sector comprises:
a plurality of memory cells;
a plurality of gate terminals coupled to at least one wordline;
a plurality of drain terminals coupled to at least one bitline;
a plurality of source terminals coupled to at least one bitline; isolating control of at least one core sector within the physical sector; and
generating an inhibiting voltage to at least one wordline of the plurality of core sectors within the physical sector by a decoder while concurrently generating an erase voltage to at least one wordline of the plurality of core sectors;
wherein the decoder comprises:
a row decoder
a circuit for generating a high voltage signal;
a sub circuit for passing a control signal for a negative voltage to be generated to at least one wordline of the plurality of core sectors or a positive voltage to at least one core sector of the plurality of core sectors;
wherein generating the inhibiting voltage comprises generating a high positive voltage from a VWL node; and
wherein generating the negative voltage comprises generating a high negative voltage from a minus voltage or a float;
forming a column decoder comprising a sense amplifier and two sector select circuits coupled to and shared among the plurality of core sectors.