Resistance Change Memory Write Circuit with Dynamic Current and Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Resistance change memories face challenges in preventing write errors due to heat generation during the transition of resistance states, as constant voltage or current applications can increase heat and affect the storage state of the resistance change element.
Innovation Solution
A write method where the write current is held constant when changing the resistance change element from a high-resistance state to a low-resistance state, and the write voltage is held constant when changing from a low-resistance state to a high-resistance state, to minimize heat generation and prevent write errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If constant voltage is applied during resistance state transition, then write operation is simplified, but heat generation increases causing write errors
Solution Approach 1:
The patent applies dynamic control of the write voltage, transitioning from constant voltage to time-varying voltage control. The write voltage is applied as a pulse with controlled width and amplitude, allowing the voltage to vary dynamically during the resistance transition process. This dynamic approach enables precise control of the transition timing while limiting total energy input and heat generation, resolving the contradiction between operational simplicity and heat control.
Solution Approach 2:
The patent employs periodic pulsed voltage application rather than continuous voltage. The write operation uses precisely timed voltage pulses that are applied only during the necessary transition period, then removed. This periodic action allows the system to achieve the resistance transition during the pulse while avoiding continuous heat generation, thus maintaining operational effectiveness while reducing thermal effects that cause write errors.
2Ease of operation
If constant current is applied during resistance state transition, then write operation is simplified, but heat generation increases affecting storage state
Solution Approach 1:
The patent implements dynamic current control where the write current varies over time during the transition process. The current is applied as a controlled pulse that increases during the transition and then decreases, rather than maintaining a constant level. This dynamic current profile achieves the resistance state transition efficiently while minimizing excess current flow that would generate harmful heat and affect the stability of the stored state.
3Speed
If high current is applied to achieve fast resistance change, then write speed is improved, but heat generation increases causing write errors
Solution Approach 1:
The patent uses short-duration high-current pulses to achieve fast resistance transitions. The current is applied intensively for a brief period just long enough to complete the transition, then immediately removed. This periodic, pulsed approach maintains high write speed by delivering the necessary current surge while minimizing the total duration of high current flow, thereby reducing cumulative heat generation and preventing write errors.
Solution Approach 2:
The patent employs a rush-through approach where a high current pulse is applied just long enough to force the resistance transition to complete, then the current is immediately reduced or removed. This skipping strategy delivers the necessary energy surge to achieve fast switching without sustaining high current levels that would generate excessive heat, thus maintaining speed while avoiding thermal write errors.
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 reduces heat generation after the resistance change, thereby minimizing write errors and resistance variations, ensuring accurate data storage in resistance change memories.
Implementation Method 1
a resistance change element having a high-resistance state and a low-resistance state in accordance with write information
Implementation Method 2
care should be taken so that the write current or voltage after the resistance has changed has no effect, e.g., causes no write error on the state of the resistance change element
Data Source
AI summary
A resistance change memory includes a resistance change element having a high-resistance state and a low-resistance state in accordance with write information, and a write circuit configured to supply a write current that the write current flowing through the resistance change element is held constant before and after the resistance change element is changed from the high-resistance state to the low-resistance state, and apply a write voltage that the write voltage applied to the resistance change element is held constant before and after the resistance change element is changed from the low-resistance state to the high-resistance state.