NVSRAM With Multiple MTJ Cells for Fast Persistent Access
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Solution Overview
Problem
Existing memory devices face challenges in achieving fast reading and writing speeds while maintaining high storage density, particularly in the combination of volatile and non-volatile memory technologies.
Innovation Solution
The integration of static random access memory (SRAM) with magnetic tunnel junction (MTJ) cells, where SRAM operates as a shared amplifier for multiple MTJ cells, and the use of pipelining and asymmetrical data storage through reference MTJ cells to enhance reading and writing speeds and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If volatile memory devices are used, then reading and writing speeds are fast, but data is lost when power is shut off
Solution Approach 1:
The patent combines volatile SRAM cells and non-volatile MTJ cells into a hybrid memory device. The SRAM cells provide fast read/write operations while the MTJ cells provide non-volatile data retention. This merging allows the system to achieve both high speed and data retention capabilities that neither technology could achieve alone.
Solution Approach 2:
The hybrid memory device performs multiple functions: it provides volatile memory functionality for fast access and non-volatile memory functionality for data retention. The SRAM and MTJ cells work together to offer both speed and persistence, making the device universally applicable for both temporary and permanent data storage needs.
2Reliability
If non-volatile memory devices are used, then data retention is maintained, but reading and writing speeds are slow
Solution Approach 1:
The patent merges SRAM and MTJ cells to create a system where MTJ cells provide non-volatile retention and SRAM cells provide fast access. The combination resolves the speed-retention tradeoff by allowing each component to excel at its strength while compensating for its weakness through the other component.
Solution Approach 2:
The SRAM cells act as an intermediary between the MTJ cells and the external circuitry. They buffer the slow write operations to MTJ cells and provide fast read operations, mediating between the non-volatile storage needs and high-speed access requirements.
3Quantity of substance
If symmetrical data storage is used, then storage density is maintained, but reading and writing speeds are limited
Solution Approach 1:
The patent employs asymmetrical data storage configurations where data is stored in non-symmetrical patterns across the memory array. This asymmetry allows for more efficient use of the memory space, increasing storage density while enabling faster access patterns by optimizing the distribution of data and reference cells.
Solution Approach 2:
The memory device is segmented into functional regions including data storage cells and reference MTJ cells. This segmentation allows specialized areas to be optimized for specific functions, with reference cells positioned to enable parallel reference operations that increase read/write speeds without sacrificing storage density.
4Quantity of substance
If more MTJ cells are added to increase storage density, then storage capacity increases, but device complexity increases
Solution Approach 1:
The reference MTJ cells serve multiple functions: they provide reference values for reading operations, enable asymmetrical storage patterns, and support parallel data access. This multi-functionality increases storage density capabilities without proportionally increasing device complexity, as the same structural elements perform multiple roles.
Solution Approach 2:
By merging reference functionality into the MTJ cell array itself rather than using separate reference structures, the patent increases storage density while minimizing the added complexity. The reference MTJ cells are integrated within the same array architecture as the data storage cells.
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
This configuration allows for faster reading and writing speeds and doubles the storage density compared to symmetrical data storage, while maintaining the advantages of both SRAM and MTJ cells.
Implementation Method 1
magnetic tunnel junction (MTJ) cells coupled to the SRAM
Data Source
AI summary
Disclosed herein is an integrated circuit including multiple magnetic tunneling junction (MTJ) cells coupled to a static random access memory (SRAM). In one aspect, the integrated circuit includes a SRAM having a first port and a second port, and a set of pass transistors coupled to the first port of the SRAM. In one aspect, the integrated circuit includes a set of MTJ cells, where each of the set of MTJ cells is coupled between a select line and a corresponding one of the set of pass transistors.