Level-Shifted Memory Voltage Switch for Bi-Directional Leakage Blocking
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Solution Overview
Problem
Current high voltage switching architectures in non-volatile memory devices, such as local pump high voltage switches and self-boosting high voltage switches, face limitations including parasitic element sensitivity, layout configuration dependence, and bi-directionality issues, which affect the performance of high voltage multiplexers and lead to reverse leakage currents.
Innovation Solution
A high voltage switch circuit comprising two switch circuits and level shift circuits coupled in series, with each switch circuit consisting of series-connected p-channel transistors and diodes for bi-directionality, and level shift circuits that drive the gates of transistors to achieve efficient switching of voltages greater than the supply voltage, providing leakage protection and reduced voltage drop across each transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If local pump high voltage switch architecture is used, then high voltage switching can be achieved, but parasitic element sensitivity and layout configuration dependence increase
Solution Approach 1:
The patent divides the high voltage switching function into multiple n-channel MOSFETs connected in series, where each transistor handles a portion of the total voltage. This segmentation reduces the voltage stress on each individual transistor and minimizes the impact of parasitic elements on the overall switching performance.
Solution Approach 2:
The patent introduces p-channel MOSFETs as intermediary devices coupled in parallel with the n-channel MOSFETs. These p-channel transistors act as protective elements that prevent reverse leakage currents and protect the n-channel transistors from voltage spikes and parasitic effects, thereby improving reliability without requiring sensitive layout configurations.
2Use of energy by moving object
If self-boosting high voltage switch architecture is used, then operational voltages are reduced, but bi-directionality is lost and reverse leakage current occurs
Solution Approach 1:
The patent merges n-channel MOSFETs and p-channel MOSFETs into a single hybrid switching circuit. The n-channel transistors provide low on-resistance for forward current conduction, while the p-channel transistors simultaneously provide reverse leakage protection. This combination enables the circuit to maintain reduced operational voltages while preventing reverse leakage currents and achieving bi-directional protection.
3Reliability
If high voltage MOS pass transistor is used with boosted gate voltage, then output voltage equals input voltage, but circuit complexity and parasitic sensitivity increase
Solution Approach 1:
The patent employs dynamic control of multiple transistors in series, where each n-channel and p-channel MOSFET pair is controlled independently through level-shifted gate signals. This dynamic approach allows precise voltage transmission while distributing the complexity across multiple simple switching units rather than requiring a single complex high-voltage transistor.
Data Source
AI summary
Voltage switches, memory devices, memory systems, and methods for switching are disclosed. One such voltage switch uses a pair of switch circuits coupled in series, each switch circuit being driven by a level shift circuit. Each switch circuit uses a group of series coupled transistors with a parallel control transistor where the number of transistors in each group may be determined by an expected switch input voltage and a maximum allowable voltage drop for each transistor. A voltage of a particular state of an enable signal is shifted up to the switch input voltage by the level shift circuits. The particular state of the enable signal turns on the voltage switch such that the switch output voltage is substantially equal to the switch input voltage.