MRAM Ternary CAM Cell Design for Faster Search Speed
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Solution Overview
Problem
Magnetic random access memory (MRAM)-based ternary content addressable memory (TCAM) cells have large sizes, resulting in slow search operations and high power consumption, which limits their efficiency in high-speed networking applications.
Innovation Solution
A MRAM-based TCAM cell design featuring a reduced size and lower power consumption, utilizing a first and second magnetic tunnel junction with a conductive line connecting them, along with selection transistors and current lines, allows for faster search operations and lower manufacturing costs, achieved through optimized heating and sense current management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If MRAM-based TCAM cell size is reduced, then search speed increases and power consumption decreases, but device complexity increases due to optimized current management
Solution Approach 1:
The patent combines multiple functions into shared current lines that serve both heating and sensing purposes. The first and second current lines are used sequentially for heating during write operations and for sensing during read operations, eliminating the need for separate dedicated lines for each function. This merging reduces the overall number of current lines while maintaining full functionality, thereby reducing device complexity while enabling faster search operations and lower power consumption.
2Use of energy by stationary object
If MRAM-based TCAM cell size is reduced, then power consumption decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs dynamic timing control of current line activation. The system switches between heating mode and sensing mode by controlling the timing of current application to shared current lines. During write operations, current lines are activated for heating; during read operations, the same lines are activated for sensing. This dynamic temporal separation allows precise control of power consumption while using standard manufacturing processes, avoiding the need for higher manufacturing precision.
3Productivity
If cell size is reduced for higher density, then productivity increases, but device complexity increases due to current line sharing
Solution Approach 1:
The patent implements universal current lines that perform multiple functions. The first and second current lines serve dual purposes: they act as heating lines during write operations and as sensing lines during read operations. The first and second straps also serve multiple functions by connecting to different magnetic tunnel junctions in different operational modes. This multi-functionality enables higher cell density and improved productivity without proportionally increasing device complexity, as the same physical structures are reused across different operational contexts.
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 design enables higher density arrays with increased search speed and reduced power consumption, leading to more efficient and cost-effective magnetic memory devices.
Implementation Method 1
a first and second magnetic tunnel junction, each magnetic tunnel junction being formed from a storage layer having a magnetization that can be switched
Implementation Method 2
allowing passing a heating current selectively through the first and second straps, respectively
Data Source
AI summary
A magnetic random access memory-based ternary content addressable memory cell (10), comprising: a first and second magnetic tunnel junction (2, 2'), each magnetic tunnel junction (2, 2') being formed from a storage layer (21), a sense layer (23), and an insulating layer between the storage layer (21) and the sense layer (23); a first and second straps (14, 14'), respectively connected to the first and second magnetic tunnel junction (2, 2'); a first and second selection transistors (6, 6'), respectively connected to one extremity of the first and second straps (14, 14'), allowing passing a heating current (31) selectively through the first and second magnetic tunnel junction (2, 2'), respectively; a first and second current lines (3, 3'), respectively connected to the other extremity of the first and second straps (14, 14'); and a first field tine (5) for passing at least a first write field current (51); wherein the cell (10) further comprises a conductive line (11) electrically connecting in series the first and second magnetic tunnel junctions (2, 2').