Semiconductor memory device and semiconductor memory system

1. A semiconductor memory device having an open bit line structure, comprising:

a unit memory bank having a plurality of memory cell mats, which shares a local data line, and divided by a row address; and

at least one dummy cell mat disposed between the plurality of memory cell mats,

wherein the dummy cell mat comprises reference bit lines corresponding to reference bit lines of the plurality of memory cell mats disposed adjacent to the dummy cell mat,

wherein the reference bit lines of the dummy cell mat corresponding to the reference bit lines of the plurality of memory cell mats are disposed to be isolated from each other.

2. The semiconductor memory device of claim 1 wherein the unit memory bank comprises:

first and second memory cell mats suitable for sharing the local data line; and

the dummy cell mat disposed between the first and second memory cell mats.

3. The semiconductor memory device of claim 2 , wherein the unit memory bank performs a row active operation on the first memory cell mat, performs a precharge operation on the first memory cell mat and the dummy cell mat, and performs a row active operation on the second memory cell mat before the precharge operation.

4. A semiconductor memory system comprising:

a semiconductor memory device having an open bit line structure; and

a controller suitable for controlling the semiconductor memory device,

wherein the controller transmits, to the semiconductor memory device, data having a first data type and data having a second data type that has an interval between consecutive write operations, which is different from that of the first data type, and

wherein the semiconductor memory device comprises:

a first memory bank that includes first and second memory cell mats suitable for sharing a first local data line, and a first dummy cell mat disposed between the first and second memory cell mats;

a second memory bank that includes third and fourth memory cell mats suitable for sharing a second local data line, and a second dummy cell mat disposed in an edge of the second memory bank; and

a selective transfer unit suitable for selectively transferring the data transferred from the controller to the first memory bank or the second memory bank based on the data type.

5. The semiconductor memory system of claim 4 , wherein the data having the first data type includes an interval between consecutive write operations that is shorter than that of the data having the second data type.

6. The semiconductor memory system of claim 4 , wherein the first memory bank performs a write operation on the second memory cell mat before a precharge operation on the first memory cell mat after a write operation on the first memory cell mat.

7. The semiconductor memory system of claim 4 , wherein the second memory bank performs a write operation on the fourth memory cell mat after a precharge operation on the third memory cell mat.

8. The semiconductor memory system of claim 4 , wherein the interval between consecutive write operations is determined from when a write command for a first write operation on a predetermined memory bank is applied, to when a write command for a second write operation on the predetermined memory bank is consecutively applied.

9. The semiconductor memory system of claim 4 , wherein the first dummy cell mat comprises reference bit lines corresponding to reference bit lines of the first and second memory cell mats.

10. The semiconductor memory system of claim 9 , wherein the reference bit lines of the first dummy cell mat corresponding to the reference bit lines of the first and second memory cell mats are disposed to be isolated from each other.

11. A semiconductor memory device having an open bit line structure, comprising:

a unit memory bank having a plurality of memory cell mats, which shares a local data line, and divided by a row address, wherein each of the memory cell mat includes cell mats and sense amplifiers; and

at least one dummy cell mat disposed between the sense amplifiers included in the plurality of memory cell mat,

wherein the unit memory bank comprises:

first and second memory cell mats suitable for sharing the local data line; and

the dummy cell mat disposed between the first and second memory cell mats.

12. The semiconductor memory device of claim 11 , wherein the dummy cell mat comprises reference bit lines corresponding to reference bit lines of the plurality of memory cell mats disposed adjacent to the dummy cell mat.

13. The semiconductor memory device of claim 12 , wherein the reference bit lines of the dummy cell mat corresponding to the reference bit lines of the plurality of memory cell mats are disposed to be isolated from each other.

14. The semiconductor memory device of claim 12 , wherein the unit memory bank performs a row active operation on the first memory cell mat, performs a precharge operation on the first memory cell mat and the dummy cell mat, and performs a row active operation on the second memory cell mat before the precharge operation.