MRAM Control Circuit Optimizes Write Power via Preliminary Read
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Solution Overview
Problem
Magnetic random access memory (MRAM) faces challenges in balancing power consumption during reading and writing operations, leading to increased power usage when used as a cache memory or main storage memory, and vice versa when used as a storage device, affecting overall memory system efficiency.
Innovation Solution
The implementation of a control circuit that selectively switches between two modes based on mode selection signals to optimize write operations by either inhibiting writing of matching bits or inverting data, depending on the number of '1' and '0' bits, to reduce power consumption during reading or writing, utilizing magnetoresistive elements with different resistance states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If MRAM is used as a cache memory or main storage memory with frequent read operations, then reading performance is improved, but power consumption during writing increases
Solution Approach 1:
The patent performs a read operation before a write operation to obtain current data from the magnetoresistive element. This preliminary read allows the control circuit to compare with incoming write data and determine which bits actually need to be rewritten, thereby reducing unnecessary write operations and lowering power consumption during writing while maintaining fast read performance
Solution Approach 2:
Instead of always performing full write operations to magnetoresistive elements, the patent applies partial writing by only rewriting bits where the write data differs from the current data. This partial action approach reduces the number of bits that need to be rewritten, thereby reducing power consumption during writing operations while preserving read performance
2Productivity
If MRAM is used as a storage device with frequent write operations, then writing efficiency is improved, but power consumption during reading increases
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit compares incoming write data with current data read from magnetoresistive elements. This feedback information is used to determine the optimal write strategy - whether to perform full writes, partial writes, or no writes at all - thereby reducing unnecessary reading operations and lowering power consumption during reading while maintaining high writing efficiency
3Speed
If conventional write operations are used without data comparison, then write speed is maintained, but power consumption increases due to unnecessary bit rewriting
Solution Approach 1:
The patent performs a preliminary read of the current data from the magnetoresistive element before executing a write operation. This preliminary action provides the control circuit with the information needed to compare against incoming write data and identify only the bits that actually need to be rewritten, thereby reducing unnecessary bit rewriting and associated energy consumption while maintaining write speed
Solution Approach 2:
The patent applies partial writing by only rewriting bits where the write data differs from the current data. This partial action approach reduces the number of bits that need to be rewritten, thereby reducing power consumption from unnecessary bit rewriting while preserving write speed for the necessary bits
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 allows MRAM to effectively reduce power consumption in both reading and writing operations, optimizing its use as either a cache memory or storage device by adapting write operations to minimize energy usage based on usage scenarios.
Implementation Method 1
magnetoresistive elements capable of storing one of a first resistance value and a second resistance value that is different from the first resistance value
Data Source
AI summary
According to one embodiment, a magnetic random access memory includes a write circuit to write s-bit (s is a natural number equal to 2 or greater) write data to magnetoresistive elements, and a read circuit to read s-bit read data from the magnetoresistive elements. The control circuit is configured to select one of first and second modes based on a mode selection signal, read the read data by the read circuit and write one of the write data and inversion data of the write data to the magnetoresistive elements by the write circuit based on the read data and the write data if free space of the buffer memory is equal to a fixed value or more when the second mode is selected.