MRAM Memory System Data Bit Inversion for Read Error Reduction
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Solution Overview
Problem
Magnetic random access memory (MRAM) devices face challenges in maintaining data integrity due to high read error rates (RER) caused by read voltages that can inadvertently program bits, especially when a major bit is '1', leading to incorrect bit flips during read operations.
Innovation Solution
A memory system and method that generates data bit inversion (DBI) information based on the majority bit of the data, inverting bits accordingly before programming, and using distinct write and read voltages to reduce RER by ensuring more bits are programmed as '0', which are less susceptible to read errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read voltage is applied to MRAM cells, then data can be read from the memory, but read errors occur due to inadvertent bit programming
Solution Approach 1:
The patent applies preliminary action by inverting data bits before programming them into the MRAM. By anticipating the potential read error issue and pre-inverting the data according to DBI information, the system prepares the data in a state that compensates for potential read errors, thus improving data integrity without changing the read operation itself.
Solution Approach 2:
The patent changes the parameter of bit state by inverting data bits from their original state to an inverted state before programming. This parameter change is controlled by DBI information and ensures that when read errors occur, the inverted bits compensate for the errors, thereby reducing the overall read error rate and improving reliability.
2Reliability
If bits are programmed as '1' in MRAM, then data storage is achieved, but read errors increase due to susceptibility of '1' bits to incorrect flipping
Solution Approach 1:
The patent systematically changes the parameter of bit state by ensuring that the majority of programmed bits are in the '0' state rather than '1' state. This is achieved by inverting data bits according to DBI information before programming. The parameter change from predominantly '1' to predominantly '0' bits reduces read errors and improves programming accuracy.
Solution Approach 2:
The patent employs a mechanism to quickly determine the major bit of incoming data and apply appropriate inversion through DBI information. This allows the system to rush through the potential error-prone state (programming majority '1' bits) and transition to the more reliable state (programming majority '0' bits) without manual intervention, thereby improving both reliability and programming accuracy.
3Ease of operation
If data is programmed without bit inversion, then programming simplicity is maintained, but read error rates increase
Solution Approach 1:
The patent implements self-service by automatically generating DBI information from the incoming data and applying the necessary bit inversions without external intervention. The system itself determines whether inversion is needed based on the major bit calculation and automatically applies the inversion, maintaining ease of operation while improving read accuracy through automated reliability enhancement.
Solution Approach 2:
The patent applies preliminary action by pre-calculating the DBI information and pre-inverting bits before the programming operation. This preliminary preparation ensures that the main programming operation remains simple and straightforward while the reliability improvement is achieved in advance through automated bit inversion based on data characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution significantly reduces read error rates and improves the reliability of MRAM systems by ensuring that a majority of bits are programmed as '0', minimizing incorrect bit flips during read operations.
Implementation Method 1
A magnetic random access memory (MRAM) using a magnetic element is one example of such nonvolatile elements
Data Source
AI summary
A memory system is provided including a host configured to generate data bit inversion (DBI) information of data according to a major bit of the data, and a nonvolatile memory device configured to invert one or more bits of the data according to the DBI information, and to program the DBI information and the data. A control method of a memory system comprises generating DBI information according to the number of “1” bits of data relative to the number of “0” bits of the data, transferring the data and the DBI information, and inverting bits of the data according to the DBI information, the inverted bits of the data being programmed at the nonvolatile memory device.