MRAM Waveform Shaping for Fast Write Speed
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Solution Overview
Problem
Conventional Magnetoresistive Random Access Memory (MRAM) technologies face challenges in achieving high-speed writing operations due to limitations in waveform shaping units, which result in inefficient current waveform rising and require significant time for capacitor charging and discharging, leading to slower writing speeds.
Innovation Solution
The implementation of a magnetic random access memory (MRAM) system with multiple cell array groups, each equipped with independent current source units and waveform shaping units that charge and discharge capacitors at different periods for bit lines and word lines, allowing for optimized waveform shaping and improved writing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If waveform shaping units with capacitors are used to control write current, then writing precision is improved, but writing speed deteriorates due to slow capacitor charging and discharging
Solution Approach 1:
The memory system is divided into multiple cell array groups (first cell array group and second cell array group), each with independent current source units and waveform shaping units. This segmentation allows parallel operation of different cell groups, where while one group is being written, another group can be precharging capacitors, thus improving overall writing speed without sacrificing precision
Solution Approach 2:
Capacitors in waveform shaping units are precharged during idle periods or when other cell arrays are being accessed. The current source units prepare write currents in advance by charging capacitors to required voltage levels before actual writing operations, reducing the time needed during actual write cycles
2Reliability
If current waveform shaping is performed to reduce overshoots, then reliability is improved, but writing speed deteriorates due to extended charging time
Solution Approach 1:
The system maintains continuous useful action by overlapping write operations across multiple cell array groups. While one cell array group undergoes write operation requiring careful waveform shaping, other groups can simultaneously perform read operations or prepare for next write cycles, ensuring the system remains continuously productive without sacrificing reliability
Solution Approach 2:
The waveform shaping units dynamically adjust capacitor charging rates and current ramp-up speeds based on the specific write requirements of each cell array group. This dynamic control allows optimization of both waveform quality for reliability and charging speed for performance
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 approach enables faster writing operations by ensuring efficient charging and discharging of capacitors, reducing overshoots, and allowing for rapid current rising, thereby enhancing the overall writing speed in MRAM systems.
Implementation Method 1
Magnetoresistive Random Access Memory (hereafter, referred to as 'MRAM')
Implementation Method 2
the pinned layer 143 is a synthetic ferrimagnet structure in which a non-magnetic layer 155 is sandwiched between a ferromagnetic layer 154 and a ferromagnetic layer 156. A direction of magnetization of the pinned layer 143 is fixed by the anti-ferromagnetic layer 144
Implementation Method 3
a write current IWBL is supplied through the write bit line WBL. Subsequently, at a temporal difference, a write current IWWL is supplied through the write word line WWL
Data Source
AI summary
An MRAM having a first cell array group (2-0)and a second cell array group (2-1) containing a plurality of cell arrays (21) is used. Each of the first cell array group (2-0) and the second cell array group (2-1) includes a first current source unit for supplying a first write current IWBL to a bit line WBL of the cell array (21) and a first current waveform shaping unit having a first capacitor requiring precharge and shaping the waveform of the first write current IWBL. When the cell array (21) performs write into a magnetic memory (24), the first current waveform shaping unit of the first cell array group (2-0) and the first current waveform shaping unit of the second cell array group (2-1) charges and discharges electric charge accumulated in the first capacitor to wiring toward the bit line WBL at different periods from each other.