Selective Write Control for Resistance Change Memory Power Reduction
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Solution Overview
Problem
Existing storage apparatuses with resistance change memory, such as MRAM or ReRAM, face inefficiencies in power consumption due to the need to rewrite entire batches of data when correcting errors, leading to unnecessary power usage when only a subset of data bits require correction.
Innovation Solution
A storage apparatus with a write control section that selectively writes specific values to only the affected cells by controlling current flow to those cells while grounding or setting other cells to high impedance, thereby minimizing power consumption by targeting only the cells requiring correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If write-back data is written in a batch to multiple cells, then data correction is achieved, but power consumption increases due to current flowing to all cells including those not requiring correction
Solution Approach 1:
The patent segments the write-back operation by selectively enabling current flow only to specific memory cells that require correction, rather than applying current to all cells in a batch. The write control section divides the memory array into targeted cells (requiring write-back) and non-targeted cells (maintaining original state), applying current only to the segmented portion that needs correction.
Solution Approach 2:
The patent implements local quality by applying different electrical states to different regions of the memory array. Targeted cells receive write current to update their data, while non-targeted cells are maintained in high-impedance state or connected to fixed potential (ground or power supply) to prevent current flow. This localized treatment ensures power is consumed only where necessary for correction.
2Reliability
If current is applied to all cells for write-back, then correction is performed, but unnecessary current flow to normal bits worsens power loss
Solution Approach 1:
The patent applies partial action by performing write-back operation on only the subset of cells that actually require correction, rather than applying the action to all cells in the memory array. The write control section identifies which specific cells contain erroneous data and limits the write current application exclusively to those cells, avoiding excessive action on cells that are already correct.
Solution Approach 2:
Different electrical conditions are applied to different regions: targeted cells receive write current pulses, while non-targeted cells are connected to fixed potential (ground or power supply) or maintained in high-impedance state. This localized differentiation ensures that energy is expended only where correction is needed, minimizing overall power loss.
3Use of energy by moving object
If selective write control is implemented, then power consumption is reduced, but control complexity increases
Solution Approach 1:
The control function is segmented into distinct components: error detection logic, write-back determination logic, and write control logic. The write control section receives write-back data and independently determines which cells require correction, then selectively applies current only to those cells. This segmentation of control functions manages complexity by organizing the selective write control into modular, manageable stages.
Solution Approach 2:
The error detection and write-back determination are performed in advance before the actual write operation. The write control section pre-identifies which cells require correction based on error detection results, then executes the selective write-back. This preliminary action simplifies the control complexity during the actual write phase, as the target cells are already identified and prepared.
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 reduces power consumption by ensuring that only the necessary cells are written to during the correction process, optimizing energy usage and extending the lifespan of the storage apparatus.
Implementation Method 1
a resistance change memory such as an MRAM or ReRAM has its retained data inverted when a current is applied to the storage elements
Implementation Method 2
the write control section performs control to let a current flow only to the cell corresponding to the position indicative of the specific value in the write-back data in a direction corresponding to the specific value
Data Source
AI summary
Provided is a storage apparatus that reduces the power needed to write corrected data back to a memory.The storage apparatus includes a memory and a write control section. The memory stores data in units of multiple cells each representing a predetermined value. The write control section receives write-back data having a specific value in a position corresponding to at least one of the multiple cells, as well as a write-back command regarding the specific value. The write control section performs control to write the specific value only to the cell corresponding to the position indicative of the specific value in the write-back data.