High-Voltage Memory Switch Circuit for Bi-Directional Leakage Control
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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 utilizing two switch circuits and level shift circuits in series, with each circuit comprising multiple p-channel transistors to manage voltage drops and ensure bi-directionality, using diodes for leakage protection and enabling control logic to manage switching states.
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 separate n-channel and p-channel transistor circuits, each handling specific voltage ranges and directions. This segmentation isolates parasitic effects to individual transistor types and allows optimized layout for each, reducing overall parasitic sensitivity while maintaining reliable high voltage switching.
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 and p-channel high voltage transistor circuits into a unified switch architecture. The n-channel transistors handle one direction of voltage switching while p-channel transistors handle the reverse direction, achieving bi-directional operation. This combination eliminates reverse leakage current by using complementary transistor types with opposite conduction characteristics.
3Power
If high voltage MOS pass transistor is used with local boosting charge pump, then voltage switching is achieved, but voltage stress on transistors increases
Solution Approach 1:
The patent applies different transistor types (n-channel and p-channel) to different parts of the switching circuit based on local voltage requirements. Each transistor is positioned and sized to handle specific voltage drops, distributing the voltage stress across multiple devices rather than concentrating it on a single pass transistor. This local optimization reduces peak voltage stress on individual transistors while maintaining overall switching capability.
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.