Series High-Voltage Memory Switch With Level Shifters for Reverse Leakage
Find Innovative SolutionsGenerate Solutions
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 dependency, 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 stress on individual transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If local pump high voltage switch architecture is used, then high voltage switching capability is achieved, but parasitic element sensitivity and layout configuration dependency increase
Solution Approach 1:
The high voltage switch is divided into multiple transistor stages (first high voltage transistor, second high voltage transistor, third high voltage transistor) connected in series. Each transistor handles a portion of the voltage switching task, reducing the voltage stress and parasitic effects on any single transistor while maintaining the overall high voltage switching capability.
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 combines features of both local pump and self-boosting architectures by using a series connection of multiple high voltage transistors with shared control signals. This merging approach maintains bi-directional switching capability while reducing the voltage stress on individual transistors, and prevents reverse leakage current through proper transistor configuration and control.
3Reliability
If high voltage MOS pass transistor is used with boosted gate voltage, then output voltage equals input voltage, but circuit complexity and parasitic element sensitivity increase
Solution Approach 1:
The high voltage transistors are controlled by control signals generated from the same charge pump that provides the high voltage input. The control circuitry uses the available high voltage signals to generate appropriate gate control voltages, making the circuit self-sufficient and reducing the need for additional external control voltage generation circuitry.
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.