Flash Memory Decoupling Circuit for Parasitic Capacitance Reduction
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Solution Overview
Problem
The existing flash memory systems face issues with parasitic capacitance and resistance between word lines and control gate lines, leading to voltage coupling and reduced accuracy in read operations due to prolonged charging and discharging times, which can result in read errors.
Innovation Solution
The implementation of a decoupling circuit with switches that adjusts the voltage of control gate lines relative to word lines during operations to mitigate parasitic capacitance and resistance effects, ensuring accurate voltage levels during read, program, and erase operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If word lines and control gate lines are placed in close proximity to enable efficient memory cell operation, then device density and operational efficiency are improved, but parasitic capacitance and resistance increase causing voltage coupling and read errors
Solution Approach 1:
The patent introduces an intermediary structure (insulating layer or barrier) between the word line and control gate line to reduce parasitic capacitance. This intermediary element allows the lines to remain in close proximity for efficient operation while preventing harmful electrical coupling, thus resolving the contradiction between density and parasitic effects.
Solution Approach 2:
The patent modifies electrical parameters by adjusting the voltage levels applied to word lines and control gate lines during different operations. By dynamically changing voltage parameters and timing sequences, the system compensates for parasitic capacitance effects and maintains accurate read operations despite close line proximity.
2Area of stationary object
If word lines and control gate lines are positioned close together to minimize space, then device area is reduced, but charging and discharging times increase due to parasitic capacitance
Solution Approach 1:
The patent applies preliminary action by pre-charging or pre-discharging the parasitic capacitance before the main read operation. This preliminary conditioning of the capacitive coupling allows the word line and control gate line to reach their operational voltage levels faster during actual read operations, reducing the effective charging and discharging time despite close positioning.
Solution Approach 2:
The patent employs periodic action through alternating voltage sequences on word lines and control gate lines during read operations. By periodically switching voltages in a coordinated sequence, the system minimizes the impact of parasitic capacitance on charging and discharging times, enabling faster operation within the constrained space.
3Power
If voltage coupling between word lines and control gate lines is strong to enable efficient signal transmission, then signal integrity is improved, but read accuracy deteriorates due to parasitic effects
Solution Approach 1:
The patent implements feedback mechanisms that monitor the voltage levels on word lines and control gate lines during read operations. Based on this feedback, the system adjusts the read voltage sequences and timing to compensate for parasitic coupling effects, maintaining both efficient signal transmission and high read accuracy despite the presence of parasitic capacitance.
Solution Approach 2:
The patent dynamically changes voltage parameters during read operations to optimize the balance between signal transmission efficiency and read accuracy. By adjusting voltage levels and timing parameters in response to parasitic coupling conditions, the system maintains strong enough signal coupling for efficient transmission while preventing accuracy degradation from parasitic effects.
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
The decoupling circuit effectively reduces parasitic capacitance and resistance, enhancing the switching speed and accuracy of flash memory systems by maintaining precise voltage levels, thereby minimizing read errors and improving overall system performance.
Implementation Method 1
parasitic capacitance and parasitic resistance between word lines and control gate lines
Implementation Method 2
parasitic capacitance and parasitic resistance between word lines and control gate lines
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A method and apparatus are disclosed for reducing the coupling that otherwise can arise between word lines and control gate lines in a flash memory system due to parasitic capacitance and parasitic resistance. The flash memory system comprises an array of flash memory cells organized into rows and columns, where each row is coupled to a word line and a control gate line.