Ferroelectric Nonvolatile Flip-Flop for Low-VDD Data Retention
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Solution Overview
Problem
In mobile devices, the reduction of driving voltage (VDD) leads to increased leakage current and performance degradation, especially in volatile systems where data is lost when power is shut off, requiring a nonvolatile flip-flop solution with low power consumption and small hardware area.
Innovation Solution
A nonvolatile flip-flop incorporating a sense amplifier and a ferroelectric transistor-based nonvolatile storage element that operates in normal, standby, and restore modes without a separate backup mode, utilizing a high ION/IOFF ratio and independent reading/writing routes to minimize power consumption and data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the driving voltage VDD is reduced to achieve low-power operation, then power consumption decreases, but transistor speed exponentially reduces and process variation increases
Solution Approach 1:
The patent changes the fundamental operating parameter from volatile to nonvolatile memory operation, allowing the system to maintain data storage capability at low VDD levels where volatile memory fails. The ferroelectric transistor enables stable operation and data retention even when the driving voltage is reduced to ultra-low levels, resolving the contradiction between low power consumption and functional performance.
2Area of moving object
If the transistor size is reduced to improve degree of integration, then integration density increases, but threshold voltage lowers and leakage current increases
Solution Approach 1:
The patent changes the material parameter of the transistor from conventional semiconductor to ferroelectric material, fundamentally altering the I-V characteristics. The ferroelectric transistor provides high ION/IOFF ratio even at scaled dimensions, enabling small transistor sizes with low leakage current through the inherent nonvolatile switching characteristics of the ferroelectric layer.
3Object-generated harmful factors
If power gating is used to reduce leakage current, then leakage current is significantly reduced, but data is lost when power is shut off requiring restore operations
Solution Approach 1:
The ferroelectric transistor inherently maintains its state without requiring continuous power or external maintenance operations. The nonvolatile nature of the ferroelectric material allows the transistor to retain its on/off state and stored data even when power is completely shut off, eliminating the need for power gating and restore operations while maintaining zero leakage current.
4Use of energy by moving object
If power is completely shut off to eliminate leakage current, then power consumption decreases, but volatile systems lose held data requiring time and power to restore
Solution Approach 1:
The ferroelectric transistor inherently maintains its state without requiring continuous power or external maintenance operations. The nonvolatile nature of the ferroelectric material allows the transistor to retain its on/off state and stored data even when power is completely shut off, eliminating the need for power gating and restore operations while maintaining zero leakage current.
5Reliability
If a separate backup mode is added to maintain data during low VDD operation, then data integrity is improved, but device complexity and hardware area increase
Solution Approach 1:
The ferroelectric transistor serves multiple functions simultaneously: it acts as the storage element, the switching device, and the low-power operation enabler in a single integrated component. This multi-functionality eliminates the need for separate backup modes, write circuits, and additional control logic, achieving high data integrity with minimal device complexity.
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 solution enables low power operation with reduced leakage current, maintaining data integrity even when power is shut off, and supports energy-harvesting devices with unstable power sources by using a ferroelectric transistor-based nonvolatile storage element with high ION/IOFF ratio, achieving efficient data storage and retrieval.
Implementation Method 1
a nonvolatile storage element which is connected to the sense amplifier or the latch and is applied with a ferroelectric transistor
Implementation Method 2
The plurality of ferroelectric transistors have opposite states and the state represents a low resistance state (LRS) or a high resistance state (HRS)
Data Source
AI summary
Exemplary embodiments provide a sensing amplifier based flip-flop applying a nonvolatile memory device which is applicable to a mobile device which has a small hardware area, uses a small control signal, does not include a separate write circuit, has low writing power consumption, a short reading time and small power consumption, and requires a low power operation.