Non-volatile Flip-Flop Using MTJ Segmentation for Low Latency
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Solution Overview
Problem
Existing non-volatile memory techniques for storing flip-flop states in portable devices, such as smartphones, face challenges with increased propagation delay and difficulty in optimizing latch performance due to the merging of circuitry, which affects power consumption and system reboot requirements during sleep mode.
Innovation Solution
A novel non-volatile magnetic resistive memory solution that separates flip-flop circuitry from the magnetic tunnel junction (MTJ) circuit, allowing for high flip-flop speed during normal operation and independent MTJ storage, using a sense circuit with a write circuit and precharging/sensing modes to manage write and read operations efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flip-flop circuitry is merged with MTJ circuit for non-volatile storage, then non-volatile storage capability is achieved, but propagation delay increases and latch performance deteriorates
Solution Approach 1:
The patent divides the system into two independent parts: a conventional flip-flop circuit for high-speed operation and a separate MTJ circuit for non-volatile storage. The flip-flop circuitry remains independent from the MTJ circuit, allowing each to be optimized for its specific function without compromising the other's performance.
Solution Approach 2:
The patent extracts the MTJ storage function from the flip-flop circuitry, creating a separate non-volatile memory component. This extraction allows the flip-flop to maintain its high-speed performance while the MTJ circuit provides non-volatile storage capability through a dedicated interface.
2Reliability
If flip-flop circuitry is merged with MTJ circuit, then non-volatile storage is achieved, but difficulty in optimizing latch performance increases
Solution Approach 1:
The patent segments the circuit into independent flip-flop and MTJ components, allowing separate optimization of latch performance in the flip-flop circuit without being constrained by MTJ circuit requirements. This independence simplifies the optimization process for each component.
Solution Approach 2:
By extracting the non-volatile storage function into a separate MTJ circuit, the patent removes the complexity of simultaneously optimizing both latch performance and storage functionality from a single merged circuit, allowing focused optimization of each component independently.
3Use of energy by moving object
If clocks are disabled and voltages are lowered for power-down mode, then power consumption is reduced, but machine state is lost requiring full system reboot
Solution Approach 1:
The patent performs preliminary action by storing the machine state in the non-volatile MTJ memory before entering power-down mode. This advance preparation ensures that the state is preserved and can be quickly restored upon waking, avoiding the need for a full system reboot and reducing wake-up time.
Solution Approach 2:
The patent creates a copy of the volatile flip-flop state into the non-volatile MTJ memory before power-down. This copying mechanism allows the original state to be preserved in non-volatile storage while the system enters low-power mode, enabling fast recovery without data loss.
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 solution enables efficient non-volatile storage of flip-flop states with reduced propagation delay and improved latch performance, allowing for faster system recovery from sleep mode without the need for full system reboot, thus optimizing power consumption and operational efficiency.
Implementation Method 1
a resistive element, having a magneto-resistive element, selectively coupled by the sense circuit to the retention sense node
Implementation Method 2
the first MTJ element can have a free layer and a pinned layer, and the second MTJ element can have a free layer and a pinned layer
Data Source
AI summary
A flip-flop has an output control node and an isolation switch selectively couples a retention sense node to the output control node. A sense circuit selectively couples an external sense current source to the retention sense node and to magnetic tunneling junction (MTJ) elements. Optionally a write circuit selectively injects a write current through one MTJ element and then another MTJ element. Optionally, a write circuit injects a write current through a first MTJ element concurrently with injecting a write current through a second MTJ element.