Negative Voltage Output Circuit for Multi-Mode Flash EEPROM
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Solution Overview
Problem
Existing apparatuses for selecting negative voltages in flash memory devices are limited to only one negative voltage and ground voltage, and cannot adapt to varying voltage levels across different modes like programming, erasure, or read, making them unsuitable for flash EEPROMs that require multiple negative voltages.
Innovation Solution
A circuit comprising switching units and a driving unit that selectively outputs a relatively lower negative voltage from among multiple negative voltage signals, using MOS transistors to manage voltage-on and voltage-off signals based on selection signals, allowing for the selection of appropriate voltages in different operational modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an apparatus is designed to select only one negative voltage and ground voltage, then the circuit structure can be simplified, but the adaptability to varying voltage levels across different modes (programming, erasure, read) is lost
Solution Approach 1:
The voltage selection apparatus is designed to handle multiple negative voltage signals (first negative voltage signal and second negative voltage signal) in addition to ground voltage, enabling it to serve multiple operational modes (programming, erasure, read) with a single unified circuit structure. The switching units and driving unit work together to selectively output any of the available voltage signals based on mode requirements, achieving multi-functionality without requiring separate dedicated circuits for each voltage selection scenario.
2Adaptability or versatility
If multiple switching units and driving units are added to support multiple negative voltages, then the adaptability to different modes is improved, but the device complexity increases
Solution Approach 1:
The voltage selection apparatus is divided into distinct functional modules: first switching unit, second switching unit, and driving unit. Each switching unit independently handles selection between specific voltage signals, while the driving unit coordinates their operation based on the operational mode. This segmentation allows the complex function of multi-voltage selection to be achieved through modular, manageable components rather than a monolithic complex circuit.
Solution Approach 2:
The driving unit receives the operational mode signal in advance and pre-configures the switching units accordingly. Based on the detected mode (programming, erasure, or read), the driving unit proactively activates the appropriate switching unit and configures the voltage signal paths before the actual voltage selection is needed, ensuring rapid and accurate voltage output without delay.
3Ease of manufacture
If the apparatus is dedicated to a single negative voltage signal, then the manufacturing precision requirements are reduced, but the reliability for flash EEPROM operations is insufficient
Solution Approach 1:
The apparatus is designed to accommodate variations in voltage signal parameters (different negative voltage levels) by providing multiple input terminals and switching paths. Each voltage signal path is independently controllable, allowing the system to adapt to different voltage requirements of flash EEPROM operations (programming, erasure, read) without requiring extremely tight manufacturing tolerances, as the electrical parameters are programmatically controlled rather than physically fixed.
Data Source
AI summary
An apparatus selectively outputs one negative voltage from among a plurality of negative voltages. The apparatus includes a first switching unit configured to perform a switching operation and output a first voltage-on signal and a first voltage-off signal according to a selection signal and a first negative voltage signal, and a second switching unit configured to perform a switching operation and to output a second voltage-on signal and a second voltage-off signal according to the selection signal and a second negative voltage signal. The apparatus also includes a driving unit to select and output one negative voltage signal from among the first and second negative voltage signals according to the first negative voltage signal, the second negative voltage signal, the first voltage-on signal, the first voltage-off signal, the second voltage-on signal, and the second voltage-off signal.