Non-volatile Storage Circuit Power Gating for MTJ Write Stability
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Solution Overview
Problem
Conventional non-volatile storage circuits using magnetic tunnel junctions (MTJs) face challenges in reducing power consumption while maintaining stable writing, as they require a large current driver and transistor group, leading to potential short circuits and increased power consumption during logic restoration.
Innovation Solution
A non-volatile storage circuit design that includes a volatile storage unit, a non-volatile storage unit, a driver unit for performing store operations, and a switch unit that shuts off power to the driver during restore operations, utilizing a distinct restore path to manage current flow and prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a driver with large current supply capacity is used to ensure sufficient current flow during writing to MTJ, then writing stability is improved, but power consumption increases during restore operation due to potential short circuits
Solution Approach 1:
The patent divides the circuit into separate restore paths for high potential side and low potential side power supplies, with independent switch units controlling each path. This segmentation prevents direct short circuits between power supplies during restore operations while maintaining stable writing capability through the MTJ.
Solution Approach 2:
The patent introduces switch units as intermediary components between the power supplies and the driver during restore operations. These switches act as mediators that control current flow, preventing direct short circuits while allowing necessary current to reach the MTJ for stable reading.
2Power
If a large transistor group with large power supply capacity is used to drive MTJ writing, then current supply capability is improved, but device complexity increases
Solution Approach 1:
The patent designs the driver unit to serve multiple functions: it can operate as an inverter during normal operations and as a current driver during restore operations. This multi-functionality reduces the need for separate dedicated circuits, thereby reducing overall device complexity while maintaining required current supply capacity.
Solution Approach 2:
The patent employs dynamic control through switch units that activate or deactivate specific current paths based on operational mode. During restore operations, the switches dynamically reconfigure the circuit to prevent short circuits, allowing the same driver circuit to function effectively without requiring permanently oversized transistor groups.
3Loss of energy
If power gating is applied to reduce leakage current, then power consumption is reduced, but current flow capability during writing operations is limited
Solution Approach 1:
The patent applies power gating in advance during restore operations by pre-activating the switch units to control power supply paths. This preliminary action ensures that power is supplied only when needed for reading operations, reducing leakage current during idle periods while maintaining the ability to provide sufficient current during active restore operations.
Solution Approach 2:
The patent implements periodic power supply control where power gating is activated during idle periods to reduce leakage current, and deactivated during restore operations when current flow is required for reading. This periodic switching between power-on and power-off states optimizes the balance between leakage reduction and current supply capability.
Data Source
AI summary
A non-volatile storage circuit (10) of an embodiment includes a volatile storage unit (11) that stores information, a non-volatile storage unit (20) into which the information in the volatile storage unit is written by a store operation, and from which the information is read out to the volatile storage unit (11) by a restore operation via a restore path different from a store path in the store operation, a driver unit (12, 15) that receives a power supply and performs the store operation, and a switch unit (13, 14, 16, 17) that shuts off the power supply to the driver unit (12, 15) during the restore operation.