Resistance Change Memory Device Voltage Control via Mirror Circuit
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Solution Overview
Problem
Existing memory devices with resistance change memory elements face challenges in controlling falling voltage, especially when a rectifier element like a diode is used as a selector, making it difficult to achieve appropriate voltage control for setting low resistance states.
Innovation Solution
A memory device configuration that includes a first circuit with a resistance change memory element and a first rectifier element in series, and a second circuit with a current source and a second rectifier element in series, where the second circuit has a mirror relationship with the first circuit, allowing for precise control of voltage and current to set low and high resistance states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rectifier element such as a diode is used as a selector element, then the memory device can be manufactured with simpler structure, but it becomes difficult to perform appropriate falling voltage control on the resistance change memory element
Solution Approach 1:
A capacitor is introduced as an intermediary element connected in parallel with the resistance change memory element. This capacitor mediates the voltage control by maintaining voltage during the fall time, enabling appropriate voltage control when using a simple rectifier element as selector. The capacitor charges during voltage rise and discharges during voltage fall, controlling the falling speed of voltage applied to the memory element.
2Device complexity
If conventional memory device structure is used, then the device complexity is reduced, but the falling voltage control precision deteriorates
Solution Approach 1:
The capacitor serves as a mediator that enhances voltage control precision without adding complex control circuits. By simply adding the capacitor in parallel with the memory element, the falling voltage profile is controlled through the capacitor's discharge characteristics, achieving precise voltage control while maintaining simple device structure.
Solution Approach 2:
The voltage fall time is controlled by changing the capacitance value of the capacitor. By adjusting the capacitor value, the falling speed of voltage can be precisely controlled to achieve the desired voltage profile for setting low resistance state, providing a simple parameter-based control mechanism.
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
Enables effective control of voltage and current to accurately set low and high resistance states in resistance change memory elements, improving the performance of memory devices when using rectifier elements as selectors.
Implementation Method 1
a first rectifier element connected in series to the resistance change memory element
Implementation Method 2
a resistance change memory element capable of setting a low resistance state or a high resistance state according to a falling speed of an applied voltage
Data Source
AI summary
According to one embodiment, a memory device includes a first circuit including a resistance change memory element capable of setting a low resistance state or a high resistance state according to a falling speed of an applied voltage, and a first rectifier element connected in series to the resistance change memory element, and a second circuit including a current source, and a second rectifier element connected in series to the current source, the second circuit having a mirror relationship with the first circuit.