Storage system and method for balanced quad-level cell (QLC) coding with margin for an internal data load (IDL) read
A storage system and method for balanced quad-level cell (QLC) coding with margin for an internal data load (IDL) read are provided. In one example, an MLC-Fine programming approach uses a balanced 3-4-4-4 coding, where the data is encoded by assigning a unique binary sequence per state. The IDL read is supported by using a unique 3-4-4-4 coding that provides at least a three-state gap between the MLC states, while using the same ECC redundancy per page. This allows for a reduced write buffer by supporting the IDL read and provides a balanced bit error rate (BER) due to the balanced mapping.
1. A storage system comprising:
a memory; and
a controller configured to:
apply a quad-level cell (QLC) 3-4-4-4 grey code to lower and middle pages of data, which induce a multi-level cell grey coding with a margin of at least a two state difference;
program the lower and middle pages of data in the memory using a multi-level cell programming operation;
read the programming of the lower and middle pages of data in the memory; and
program upper and top pages of data in the memory to induce a quad-level cell (QLC) distribution using the read lower and middle pages.
2. The storage system of claim 1 , wherein the read data is retrieved without using error correction.
3. The storage system of claim 1 , wherein the lower, middle pages are read from the memory array without retrieving them from a write buffer in the controller.
4. The storage system of claim 1 , wherein the memory comprises a three-dimensional memory.
5. The storage system of claim 1 , wherein the storage system is configured to be embedded in a host.
6. The storage system of claim 1 , wherein the storage system is configured to be removably connected to a host.
7. In a storage system comprising a memory and a controller, a method comprising:
programming lower and middle pages of data in the memory using a multi-level cell programming operation;
generating an exclusive-or of the lower and middle pages of data in the memory;
storing the exclusive-or of the lower and middle pages of data in the storage system;
reading the programming of the lower and middle pages of data in the memory;
decoding the lower and middle pages of data using the exclusive-or of the lower and middle pages of data; and
programming upper and top pages of data in the memory.
8. The method of claim 7 , wherein the exclusive-or of the lower and middle pages of data is stored in a temporary location in the storage system.
9. The method of claim 7 , wherein the read data is retrieved without using error correction.
10. The method of claim 7 , wherein the lower, middle pages are read from the memory array without retrieving them from a write buffer in the controller.
11. The method of claim 7 , wherein the memory comprises a three-dimensional memory.
12. The method of claim 7 , wherein the storage system is configured to be embedded in a host.
13. The method of claim 7 , wherein the storage system is configured to be removably connected to a host.
14. A storage system comprising:
a memory;
means for applying a quad-level cell (QLC) 3-4-4-4 grey code to lower and middle pages of data, which induce a multi-level cell grey coding with a margin of at least a two state difference;
means for programming the lower and middle pages of data in the memory using a multi-level cell programming operation;
means for reading the programming of the lower and middle pages of data in the memory; and
means for programming upper and top pages of data in the memory to induce a quad-level cell (QLC) distribution.
15. The storage system of claim 14 , wherein the read data is retrieved without using error correction.
16. The storage system of claim 14 , wherein the lower, middle pages are read from the memory array without retrieving them from a write buffer in the controller.
17. The storage system of claim 14 , wherein the memory comprises a three-dimensional memory.
18. The storage system of claim 14 , wherein the storage system is configured to be embedded in a host.
19. The storage system of claim 14 , wherein the storage system is configured to be removably connected to a host.