MTJ Nonvolatile Latch Circuit for Scalable High-Frequency Flip-Flops
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing nonvolatile latch circuits face challenges in scalability and high endurance requirements, especially when made finer, due to the limitations of ferroelectric capacitors and the need for high endurance in flip-flop operations at high frequencies.
Innovation Solution
A nonvolatile latch circuit design incorporating spin injection type MTJ elements with resistance that changes based on current flow direction, allowing for scalable and low-power operation without the need for frequent data writing, utilizing control signals to manage latch operations and reduce power supply propagation delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferroelectric capacitors are used in storage elements to create nonvolatile sequential circuits, then data retention during power interception is improved, but scalability deteriorates because making the circuit fine reduces the readout margin
Solution Approach 1:
The patent changes the storage mechanism from ferroelectric capacitor polarization states to resistance states of MTJ elements. By utilizing the high resistance ratio characteristic of MTJ elements (parallel vs. antiparallel magnetization states), the circuit achieves nonvolatility without relying on ferroelectric effects, thereby improving scalability while maintaining data retention capability
Solution Approach 2:
The patent replaces the ferroelectric capacitor-based storage mechanism with an MTJ (magnetic tunnel junction) element-based mechanism. This substitution eliminates the need for large-area ferroelectric capacitors, enabling finer circuit dimensions while maintaining nonvolatile data storage functionality through magnetic resistance states
2Speed
If two nonvolatile latch circuits are connected to form a flip-flop operating at 1 GHz, then operation frequency is improved, but endurance requirement increases to 8.64×10^13 times per day
Solution Approach 1:
The patent implements a power management strategy where power is periodically intercepted during non-operation periods and restored when operation is needed. The nonvolatile latch circuit maintains data during power interception, eliminating the need for continuous operation and thereby dramatically reducing the cumulative endurance requirements while maintaining high operating frequency when powered
Solution Approach 2:
The MTJ-based nonvolatile latch circuit automatically maintains its data state without requiring continuous power supply or refresh operations. The magnetic resistance states are inherently stable and self-maintaining, eliminating the need for external intervention to preserve data during power interception, thus reducing overall system complexity and endurance demands
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
The design achieves scalable nonvolatile latch and flip-flop circuits that operate at high frequencies without the need for high endurance, reducing power dissipation and maintaining data integrity even when the power supply is intercepted.
Implementation Method 1
first and second injection type MTJ elements provided between the driving power supply and the first and second logic gates and changing in resistance depending upon a current flow direction
Implementation Method 2
spin injection type MTJ (Magnetic Tunnel Junction) elements R1 and R2... Depending upon the direction flow of the current, the magnetization direction of the magnetization free layer becomes parallel to (the same direction as) the magnetization direction of the magnetization pinned layer or becomes anti-parallel to (opposite to) the magnetization direction of the magnetization pinned layer
Data Source
AI summary
A nonvolatile latch circuit includes: a first gate part controlling to load or intercept an input signal based on a gate signal; a first logic gate functioning as an inverter or a gate outputting a constant voltage in response to the first control signal; a second logic gate functioning as an inverter or a gate outputting the constant voltage in response to the first control signal; a second gate part controlling to load or intercept the output of the second logic gate based on an inverted signal of the gate signal and sends the output of the second logic gate to an first input terminal of the first logic gate; and first and second injection type MTJ elements provided between the driving power supply and the first and second logic gates and changing in resistance depending upon a current flow direction.