Transistor Charge Sharing Circuit for Flash Memory Protection
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Solution Overview
Problem
Conventional FLASH memory devices are susceptible to damage from unexpected transient conditions such as power loss or voltage spikes during operating modes, which can lead to device inoperability due to permanent physical damage to transistors.
Innovation Solution
A charge sharing circuit and control logic are implemented to establish a charge sharing path between the gate and bulk nodes of transistors, enabling equalization of charge differences and decoupling from supply voltages during conditions like power loss, thereby reducing the risk of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage is applied to gate and bulk nodes during erase operation, then erase function is achieved, but transistor damage occurs upon power loss
Solution Approach 1:
A charge sharing circuit is introduced as an intermediary between the gate node and bulk node. This circuit includes a switch that can couple the gate and bulk nodes together, allowing charge to redistribute and equalize. When power loss is detected, the switch closes to create a charge sharing path, preventing dangerous voltage differentials from forming across the transistor structure.
Solution Approach 2:
The charge sharing circuit is activated in advance upon detection of power loss conditions, before destructive voltage differentials can fully develop. The control circuit monitors for power loss and preemptively couples the gate and bulk nodes through the charge sharing path, equalizing charges before they can create harmful voltage spikes that would damage the transistor.
2Reliability
If charge sharing circuit is always active, then transistor protection is improved, but device complexity increases
Solution Approach 1:
The charge sharing circuit is designed with a switch that dynamically changes its state based on operating conditions. During normal operation, the switch remains open and the charge sharing circuit is disconnected, avoiding unnecessary complexity. When power loss is detected, the control circuit activates the switch to enable charge sharing only when needed, making the protection mechanism conditional rather than continuous.
Solution Approach 2:
A control circuit implements feedback by monitoring the operational state of the memory device and detecting power loss conditions. Based on this feedback, the control circuit selectively activates or deactivates the charge sharing circuit. This feedback mechanism ensures the protection circuit is only engaged when actually needed, minimizing its impact on overall device complexity while maintaining reliability.
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 solution effectively reduces the incidence of destructive voltage establishment across transistors, preventing physical damage and maintaining device operability by equalizing charges and decoupling from supply voltages during transient conditions.
Implementation Method 1
a charge sharing circuit may be coupled between gate and bulk nodes of a transistor, and the charge sharing circuit is configured to equalize charge difference between the gate and bulk nodes
Data Source
AI summary
Apparatuses and methods for protecting transistors through charge sharing are disclosed herein. An example apparatus includes a transistor comprising a gate node and a bulk node, a charge sharing circuit coupled between the gate and bulk nodes, and logic. The charge sharing circuit is configure to equalize charge differences between the gate and bulk nodes, and the logic is configured to enable the charge sharing circuit based at least in part on a combination of first and second signals, which indicate the presence of a condition.