Bidirectional Selector SOM Readout Circuit for Offset Compensation
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Solution Overview
Problem
Resistive memory devices face read errors and reduced sensing margin due to asymmetry in the sense circuit, affecting the accuracy and performance of bidirectional selector memory cells.
Innovation Solution
The memory device incorporates a sense circuit with a switch to electrically connect sensing nodes, a capacitor to pre-charge a sensing input node, and a comparing circuit to determine the logic state based on voltage levels, compensating for offset voltages and reducing asymmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional sense circuit is used for bidirectional selector memory cells, then the circuit structure is simple, but sensing accuracy is reduced due to asymmetry and offset voltages
Solution Approach 1:
The patent applies asymmetry by intentionally introducing a dummy memory cell with opposite polarity to counterbalance the inherent asymmetry in the sense circuit. This creates a symmetric compensation effect where the dummy cell's characteristics mirror those of the actual memory cell, eliminating offset voltages and improving sensing accuracy without requiring complex additional circuitry.
Solution Approach 2:
The patent uses a dummy memory cell as an intermediary element that mediates the sensing process. This dummy cell serves as a reference that absorbs and compensates for circuit asymmetries, allowing the actual memory cell to be read with high accuracy. The dummy cell acts as a buffer that isolates the sensing circuit from the effects of asymmetry.
2Productivity
If read operations are performed on bidirectional selector memory cells, then data can be accessed, but read errors increase due to sense circuit asymmetry
Solution Approach 1:
The patent changes the parameter configuration by introducing a dummy memory cell with opposite polarity characteristics. This parameter change allows the sense circuit to operate symmetrically during read operations, eliminating the conditions that cause read errors while maintaining full read operation capability for bidirectional selector memory cells.
3Ease of manufacture
If asymmetry in the sense circuit is present, then device fabrication is simpler, but sensing margin is reduced leading to read errors
Solution Approach 1:
The patent segments the sensing function by separating the actual memory cell sensing from the asymmetry compensation function. The dummy memory cell is dedicated solely to compensating for circuit asymmetries, while the actual memory cells maintain their simple structure for easy fabrication. This segmentation allows each component to be optimized independently.
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 improves sensing accuracy and reduces chip size by eliminating asymmetry in the sense circuit, enhancing the operating performance of the memory device.
Implementation Method 1
a capacitor connected between the second sensing node and a sensing input node
Implementation Method 2
a comparing circuit configured to compare a voltage level of the sensing input node with a voltage level of a reference voltage and output a signal indicating the logic state of the selected memory cell
Implementation Method 3
a logic state of the material film is programmed based on whether the material film is in a crystalline state or an amorphous state
Data Source
AI summary
A memory device performs a read operation of bidirectional switching memory cells. The memory device includes a plurality of memory cells, each of the plurality of memory cells including a material film, an access circuit, and a sense circuit. A logic state of the material film is programmed based on whether the material film is in a crystalline state or an amorphous state. The access circuit applies a first voltage to a first electrode of a selected memory cell from among the plurality of memory cells and applies a second voltage to a second electrode of the selected memory cell, and the sense circuit determines a logic state of the selected memory cell based on electrical reactions of a first sensing node and a second sensing node connected to the selected memory cell with regard to the first voltage and the second voltage.