Memristor Write Circuit Current Control for Conductance Precision
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Solution Overview
Problem
The existing incremental step pulse programming (ISPP) technology for memristor units requires a large number of 'read verification-correction' processes, leading to prolonged time for adjusting conductance, which hampers the speed and accuracy of data writing.
Innovation Solution
A storage device with a current-controlled circuit that limits the current passing through the memristor unit to a target current, determined based on the target conductance and gate voltage, allowing the write circuit to adjust the conductance directly without the need for continuous verification, thereby avoiding the 'read verification-correction' process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ISPP technology with read verification-correction is used to adjust conductance, then manufacturing precision of conductance is improved, but time for adjusting conductance increases
Solution Approach 1:
The patent pre-calculates and stores the relationship between pulse voltage and conductance variation in a variation amount table before actual programming. This preliminary action allows the system to directly lookup the required pulse voltage for desired conductance adjustment without iterative verification, thus improving precision while reducing time.
Solution Approach 2:
The patent creates a variation amount table that copies and stores the conductance variation characteristics of memristor units. This table serves as a reference model that enables direct determination of programming parameters without real-time verification, resolving the contradiction between precision and time.
2Reliability
If ISPP technology with read verification-correction is used, then reliability of conductance adjustment is improved, but productivity decreases
Solution Approach 1:
The patent performs preliminary characterization of memristor units to build variation amount tables that capture conductance adjustment patterns. This advance preparation ensures reliable conductance programming while eliminating time-consuming verification loops, thus improving both reliability and productivity.
Solution Approach 2:
The patent changes the programming approach from iterative voltage adjustment with verification to direct voltage selection based on pre-stored variation data. This parameter change in the programming methodology maintains reliability while significantly improving data writing speed.
3Manufacturing precision
If multiple read verification-correction processes are performed, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent copies the complex conductance variation characteristics into a pre-built variation amount table. This allows the programming circuit to use simple table lookup operations instead of complex iterative verification logic, reducing circuit complexity while maintaining precision.
Solution Approach 2:
The patent performs the complex characterization and verification processes in advance during manufacturing or initialization, storing the results in variation amount tables. This preliminary action simplifies the runtime programming operation while preserving high precision conductance adjustment.
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 significantly reduces the time required to adjust the conductance of memristor units, enhancing the speed and accuracy of data writing by eliminating the need for extensive verification processes.
Implementation Method 1
a current-controlled circuit, configured to limit a current passing through the memristor unit to a target current, where the target current is determined based on target conductance of the memristor unit and a gate voltage of the transistor
Implementation Method 2
A memristor, referred to as a memory resistor, is a circuit component indicating a relationship between magnetic flux and a charge
Implementation Method 3
the resistance value of the memristor is determined by a charge flowing through the memristor
Data Source
AI summary
A storage device may be used in a neural network. The storage device includes a memristor unit, a current-controlled circuit, and a write circuit. The memristor unit has a structure of one-transistor and one-resistive random access memory (1T1R). The current-controlled circuit is configured to limit a current passing through the memristor unit to a target current, where the target current is determined based on target conductance of the memristor unit and a gate voltage of the transistor, and the target conductance is used to indicate target data to be written into the memristor unit. The write circuit is configured to load a write voltage to the memristor unit in cooperation with the current-controlled circuit, to write the target data to the memristor unit.