Resistance Variable Memory Apparatus Voltage Current Control
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Solution Overview
Problem
Conventional resistance variable memory apparatuses using electric pulses of identical polarity face issues with incorrect operation and breakdown when switching between high-resistance and low-resistance states, particularly due to uncontrolled current and voltage levels.
Innovation Solution
Incorporating a resistance variable memory apparatus with a voltage restricting active element and a current restricting active element, connected in series with the resistance variable element, to set predetermined voltage and current limits, ensuring safe switching between resistance states without excessive stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistance variable element is switched between high-resistance and low-resistance states using electric pulses of identical polarity, then data can be stored according to resistance change, but incorrect operation and breakdown occur due to uncontrolled current and voltage levels
Solution Approach 1:
A constant current circuit is introduced as an intermediary between the pulse generation circuit and the resistance variable element. This constant current circuit acts as a mediator that converts the pulse signal into a controlled current that flows through the resistance variable element, preventing excessive current and voltage stress while enabling reliable switching between resistance states.
Solution Approach 2:
The invention changes the control parameter from direct voltage pulsing to constant current operation. By maintaining a constant current through the resistance variable element and varying only the voltage applied to the constant current circuit, the system achieves reliable resistance state switching without the harmful effects of uncontrolled voltage and current spikes.
2Productivity
If conventional resistance variable memory apparatuses are used, then data can be stored, but high-speed writing cannot be achieved without prior state reading
Solution Approach 1:
The constant current circuit is configured to automatically adapt to the resistance state of the resistance variable element before the writing operation begins. This preliminary adaptation eliminates the need for prior state reading by ensuring the correct current level is already established when the write pulse is applied, enabling high-speed writing without time loss.
3Ease of operation
If voltage and current levels are not restricted during switching, then switching can occur, but breakdown and incorrect operation result
Solution Approach 1:
The constant current circuit incorporates feedback mechanisms that continuously monitor the resistance state of the resistance variable element and adjust the current accordingly. This feedback ensures that the current remains within safe limits during switching operations, preventing breakdown and incorrect operation while maintaining ease of operation.
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
Prevents incorrect operation and breakdown by maintaining controlled voltage and current levels, enhancing the reliability and longevity of the memory apparatus while allowing high-speed writing without prior state reading.
Implementation Method 1
a resistance variable element which is switchable to a high-resistance state and to a low-resistance state in response to applied electric pulses which are identical in polarity and are different in voltage level
Data Source
AI summary
A resistance variable memory apparatus (10) of the present invention comprises a resistance variable element (1) which is switched to a high-resistance state when a voltage exceeds a first voltage and is switched to a low-resistance state when the voltage exceeds a second voltage, a controller (4), a voltage restricting active element (2) which is connected in series with the resistance variable element (1); and a current restricting active element which is connected in series with the resistance variable element (1) via the voltage restricting active element (2), and the controller (4) is configured to control the current restricting active element (3) so that a product of a current and a first resistance value becomes a first voltage or larger and to control the voltage restricting active element (2) so that the voltage between electrodes becomes smaller than a second voltage when the element is switched to the high-resistance state, while the controller (4) is configured to control the current restricting active element (3) so that an absolute value of a product of the current and the second resistance value becomes the second voltage or larger and an absolute value of a product of the current and the first resistance value becomes smaller than the first voltage, when the element is switched to the low-resistance state.