Semiconductor Write Control Circuit for MTJ Energy Reduction
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Solution Overview
Problem
Existing nonvolatile flip-flop circuits consume a large amount of energy when writing data to magnetic tunnel junction (MTJ) elements, leading to increased energy consumption even during power gating, as they require a significant current flow, which diminishes the energy savings intended by the power gating process.
Innovation Solution
A semiconductor device with a write control section that compares data stored in MTJ elements with data held in a flip-flop and only writes to the MTJ elements when the data does not match, using switch elements to control the connection between the flip-flop and the nonvolatile storing section, thereby reducing unnecessary write operations and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is written to MTJ elements during power gating, then data retention is ensured, but energy consumption increases due to large current flow
Solution Approach 1:
Instead of always performing full write operations to MTJ elements, the patent applies partial action by conditionally writing data only when necessary (when flip-flop data differs from MTJ data). This reduces the frequency and extent of energy-consuming write operations while still ensuring data retention reliability when needed.
Solution Approach 2:
The patent implements a feedback mechanism by comparing the data in the flip-flop with the data in the MTJ elements before performing write operations. This feedback loop (comparison → conditional write decision) prevents redundant writes and reduces energy consumption while maintaining data integrity.
2Use of energy by moving object
If write control section compares data before writing, then energy consumption is reduced, but device complexity increases
Solution Approach 1:
The write control section performs multiple functions: it compares data between flip-flop and MTJ elements, determines write necessity, controls write operations, and manages the overall power gating process. By making this single section multi-functional, the patent reduces the need for separate dedicated circuits for each function, thereby limiting the increase in device complexity.
3Use of energy by moving object
If power gating is implemented, then energy consumption is reduced, but data loss occurs without nonvolatile storage
Solution Approach 1:
The patent performs preliminary action by transferring data from volatile flip-flops to nonvolatile MTJ elements before cutting off the power supply. This preliminary data transfer ensures that data is preserved in nonvolatile storage before the volatile memory loses its data due to power cutoff, thus preventing data loss while enabling energy reduction through power gating.
Solution Approach 2:
The patent introduces MTJ elements as an intermediary nonvolatile storage medium between the volatile flip-flops and the external environment. This intermediary preserves data during power gating by maintaining it in nonvolatile form when power is cut, bridging the gap between volatile processing and power savings.
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 significantly reduces the energy consumed during data writing to the nonvolatile storing section, minimizing wasteful energy usage and maintaining data integrity by avoiding redundant write operations.
Implementation Method 1
PTL 2 describes a nonvolatile flip-flop circuit that uses magnetic tunnel junction (MTJ) elements making up a nonvolatile storing section for storing the internal state and internal data when the supply of the source voltage is cut off
Data Source
AI summary
This invention relates to a semiconductor device that reduces energy consumed to write data to a nonvolatile storing section. A write control circuit 34 stores the same data as that held in MTJ elements MTJ1 and MTJ2. In a store operation storing the data held in a slave latch 32 into the MTJ elements MTJ1 and MTJ2, the write control circuit 34 compares the data stored therein with the data held in the slave latch 32 to control whether or not to write the data to the MTJ elements MTJ1 and MTJ2. If the internally stored data coincides with the data held in the slave latch 32, the write control circuit 34 performs control not to write the data to the MTJ elements MTJ1 and MTJ2.