Nonvolatile Memory Write Voltage Control via Local Selector Current
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Solution Overview
Problem
Conventional nonvolatile semiconductor memory experiences variations in write voltage and speed due to wiring resistance and manufacturing variations, leading to potential write defects and inefficiencies in data storage.
Innovation Solution
The implementation of a control circuit that sets a write voltage for memory devices by controlling the gate voltage of selectors, eliminating the effect of wiring resistance and ensuring consistent write voltage across the chip, thereby maintaining accurate write speed and data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a hierarchical selector structure is used to increase memory capacity, then memory capacity increases, but wiring resistance increases causing write voltage variations
Solution Approach 1:
The patent changes the control parameter from write voltage (supplied from write circuit) to write control current (generated locally in selector). By controlling current instead of voltage, the system eliminates the impact of wiring resistance variations on write voltage, thereby maintaining consistent write characteristics across large memory arrays with hierarchical selectors.
Solution Approach 2:
The patent introduces a control circuit as an intermediary between the write circuit and memory devices. This control circuit generates write control current locally in each selector, acting as a mediator that compensates for wiring resistance effects and ensures uniform write operation across all memory devices regardless of their position in the hierarchical structure.
2Device complexity
If write voltage is supplied from a centralized write circuit, then circuit control is simplified, but wiring resistance causes write speed variations
Solution Approach 1:
The patent segments the write control function by distributing control circuits to each selector throughout the memory array. Instead of one centralized write circuit controlling all memory devices, multiple distributed control circuits generate write control current locally, reducing the impact of long wiring paths and resistance variations on write speed consistency.
3Quantity of substance
If memory devices are arranged in a large array, then memory capacity increases, but layout variations affect write voltage
Solution Approach 1:
The control circuit acts as a local intermediary that generates write control current independently of the centralized write circuit. This local current generation compensates for layout variations and wiring resistance differences, maintaining stable write voltage characteristics across large memory arrays with varying device layouts.
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 allows for precise control of write voltage and current, reducing variations in write speed and enhancing data storage accuracy, making it suitable for multilevel memory applications and achieving high integration with minimal controllable range issues.
Implementation Method 1
variations in write voltage and speed due to wiring resistance and manufacturing variations
Implementation Method 2
The selector controls a write control current into a memory device. The selector also determines a write voltage into the memory device.
Data Source
AI summary
The nonvolatile semiconductor memory includes a plurality of memory devices for storing data, a write circuit for supplying a high voltage for data writing, a plurality of selectors connected between the write circuit and the plurality of memory devices, for selecting one from the plurality of memory devices; and a control circuit for selecting one from the plurality of selectors, inputting a control voltage to a control terminal of the selected selector, and setting a write voltage for the memory device according to the control voltage.