Voltage Supply Circuit for Semiconductor Memory Devices
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Solution Overview
Problem
Semiconductor memory devices face challenges in quickly raising operating voltages due to high loads from global word lines, which are not adequately reduced by existing methods, leading to prolonged pass voltage rising times.
Innovation Solution
A voltage supply circuit and semiconductor memory device design that redistributes charges stored in a line capacitor by precharging unselect local word lines and coupling them with global word lines, reducing the load on the output node and accelerating the rise of the pass voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of global word lines is increased to support higher integration, then the capacity of the memory device is improved, but the load on the output node is greatly increased and the pass voltage rising time is prolonged
Solution Approach 1:
The patent applies preliminary action by precharging unselected local word lines before the main operation. The precharge unit charges the line capacitor of unselected local word lines in advance, so that when the operation starts, the charges are already available and can be redistributed to quickly raise the pass voltage without waiting for the main pump circuit to charge everything from scratch.
Solution Approach 2:
The patent introduces an intermediary mechanism by adding a line capacitor coupled to both the global word line and unselected local word lines. This line capacitor acts as a mediator that stores charges and enables charge redistribution between the global and local word lines, facilitating fast pass voltage rise without increasing the pump capacitor size.
2Power
If the pump capacitor size is increased to supply higher loads, then the power supply capability is improved, but the circuit area is greatly increased
Solution Approach 1:
The patent segments the power supply function by dividing the word lines into selected and unselected groups, and by introducing local line capacitors that handle the charging of unselected lines. This segmentation allows the main pump capacitor to be smaller since it only needs to supply the selected word lines, while the line capacitors handle the additional load of unselected lines through charge redistribution.
Solution Approach 2:
The line capacitor serves as an intermediary energy storage element that supplements the pump capacitor. Instead of making the pump capacitor large enough to handle all loads, the line capacitor mediates by storing charges from the global word line and redistributing them to unselected local word lines, thereby reducing the required pump capacitor area.
3Quantity of substance
If existing methods (half string method or reducing global word lines) are used to reduce load, then the line and junction capacitor loads are reduced, but the pass voltage rising time is not greatly reduced
Solution Approach 1:
The patent applies preliminary action by precharging unselected local word lines before the main operation. The precharge unit charges the line capacitor of unselected local word lines in advance, so that when the operation starts, the charges are already available and can be redistributed to quickly raise the pass voltage without waiting for the main pump circuit to charge everything from scratch.
Solution Approach 2:
The patent changes the parameter of charge distribution by introducing a line capacitor that can store and redistribute charges. Instead of simply reducing the number of global word lines or using half-string methods, the system changes how charges are distributed by enabling fast charge redistribution from the line capacitor to the selected word lines during the 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
This approach significantly reduces the time it takes for the pass voltage to rise, enhancing the driving ability of the voltage generator and minimizing the size of the pump capacitor, thereby improving the efficiency and speed of semiconductor memory device operations.
Implementation Method 1
a line capacitor coupled to the global word line and the unselected local word line, and charges stored in the line capacitor are redistributed to raise the pass voltage quickly when the operation starts
Implementation Method 2
a precharge unit configured to supply a precharge voltage to an unselect local line switch adjacent to a select local line switch to which the operating voltage will be supplied
Data Source
AI summary
A voltage supply circuit includes a high voltage generator configured to generate an operating voltage, a global word line switch configured to transfer the operating voltage to global word lines, a plurality of local line switches coupled to the global word lines and configured to transfer the operating voltage to corresponding local word lines, a precharge unit configured to supply a precharge voltage to an unselect local line switch adjacent to a select local line switch to which the operating voltage will be supplied, from among the plurality of local line switches, in a preparation section before an operation is started, and a coupling unit configured to couple the unselect local line switch and the global word line switch when the operation is started.