RRAM Forming Control via Feedback Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The forming process in RRAM devices is challenging due to the need for precise control of voltage or current, as excessive energy can lead to an overly conductive state, making subsequent RESET processes difficult, while insufficient energy may result in unsuccessful channel formation, and the self-accelerating nature of the process complicates closed-loop control.
Innovation Solution
A feedback circuit system comprising a MOSFET, Trans-Impedance Amplifier (TIA), and a comparator is used to manage the forming process in RRAM cells within a crossbar circuit, allowing for automatic termination of the forming process once a channel is formed, utilizing a combination of DC or pulse ramping signal generators for controlled voltage or current application, and ensuring low power consumption with minimal propagation delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher forming voltage or current is applied to ensure successful channel formation, then the forming success rate is improved, but the RRAM device transitions into an overly-conductive state causing difficulties for subsequent RESET process
Solution Approach 1:
The patent implements a feedback circuit that continuously monitors the current through the RRAM device during the forming process. When the current exceeds a predetermined threshold indicating successful channel formation, the feedback circuit automatically terminates the forming voltage application. This prevents over-forming and the resulting overly-conductive state while ensuring reliable channel formation.
2Manufacturing precision
If the forming process is allowed to proceed without interruption to ensure complete channel formation, then the channel formation completeness is improved, but over-forming occurs within a few nanoseconds making control difficult
Solution Approach 1:
The feedback circuit provides real-time monitoring and automatic termination capability that stops the forming process precisely when the channel is formed. This eliminates over-forming while maintaining complete channel formation, and the automated control reduces the complexity of manual timing control.
Solution Approach 2:
The forming process itself generates the signal needed for termination - when the channel forms, the current naturally increases, which the feedback circuit detects and uses to trigger automatic termination. The system uses its own operational characteristics to control itself.
3Device complexity
If traditional open-loop forming method is used to simplify the control circuit, then the device complexity is reduced, but fast closed-loop control is required due to the self-accelerating nature of the forming process
Solution Approach 1:
The patent implements a feedback circuit that continuously monitors the current through the RRAM device during the forming process. When the current exceeds a predetermined threshold indicating successful channel formation, the feedback circuit automatically terminates the forming voltage application. This prevents over-forming and the resulting overly-conductive state while ensuring reliable channel formation.
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 provides precise control over the forming process, reducing over-forming, enabling faster and more accurate channel formation, enhancing the performance of RRAM crossbar arrays for applications like real-time image recognition and neural computing, while maintaining low power consumption and scalability.
Implementation Method 1
a TIA connected to the MOSFET via the source terminal
Implementation Method 2
a comparator having a first input end, a second input end, and an output end, wherein the comparator is connected to the TIA via the first input end, the second input end is connected to a reference voltage source
Data Source
AI summary
Technologies relating to controlling forming process in RRAM devices implemented in a cross-bar circuit using one or more feedback circuits are disclosed. An example apparatus includes an RRAM cell configured to form a channel; a MOSFET having a drain terminal, a source terminal, and a gate terminal, wherein the MOSFET is connected to the RRAM cell via the drain terminal; a TIA connected to the MOSFET via the source terminal; a first signal generator connected to the RRAM cell; a second signal generator connected to the MOSFET via the gate terminal; and a comparator having a first input end, a second input end, and an output end, wherein the comparator is connected to the TIA via the first input end, the second input end is connected to a reference voltage source, and the output end is connected to the first signal generator and the second signal generator.