Negative Voltage Generator Circuit for NAND Flash Read Speed
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Solution Overview
Problem
Current NAND flash memory devices face challenges in achieving faster read speeds due to limitations in generating negative read voltages, which affect the performance of multi-level cells and require improved voltage generation techniques.
Innovation Solution
The implementation of a negative voltage generator circuit that includes a negative voltage pump and regulator, utilizing an amplifier circuit and voltage booster to rapidly and reliably generate negative target voltages, enhancing the read performance by efficiently managing voltage levels and switching times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional voltage generation methods are used in NAND flash memory devices, then device complexity is reduced, but read speed is insufficient
Solution Approach 1:
The voltage generator is divided into distinct functional modules: a negative voltage pump that generates initial negative voltage, and a negative voltage regulator that includes an amplifier circuit and voltage booster circuit. This segmentation allows each module to be optimized for its specific function, enabling faster voltage generation and switching while maintaining manageable overall system complexity.
Solution Approach 2:
The negative voltage pump pre-generates negative voltage before the regulator needs it, and the amplifier circuit is designed to rapidly amplify this pre-generated voltage. This preliminary action eliminates waiting time for voltage generation, directly improving read speed without requiring overly complex real-time voltage synthesis circuits.
2Speed
If voltage generation is slowed down to ensure stability, then reliability improves, but read speed decreases
Solution Approach 1:
The amplifier circuit in the negative voltage regulator incorporates feedback mechanisms that continuously monitor the generated voltage and adjust the amplification accordingly. This feedback ensures that the rapidly generated voltage remains stable and accurate, resolving the contradiction between fast generation speed and voltage stability.
Solution Approach 2:
The voltage generator employs dynamic switching between different circuit configurations and adjustable amplification levels. The amplifier circuit can dynamically adapt its gain and the voltage booster can dynamically adjust its boosting ratio based on operational requirements, enabling both fast response and stable output voltage.
3Reliability
If simple voltage regulation is used, then device complexity is low, but negative target voltage cannot be generated reliably and rapidly
Solution Approach 1:
The amplifier circuit and voltage booster circuit are merged into a single integrated negative voltage regulator module. This combination allows the amplifier to rapidly amplify the negative voltage from the pump while the booster simultaneously provides additional voltage enhancement, achieving reliable and rapid negative target voltage generation without requiring separate independent circuits for each function.
Solution Approach 2:
The negative voltage regulator is designed as a multi-functional unit that can generate multiple negative voltage levels (first negative voltage and second negative voltage) using the same amplifier and booster circuits. This universality reduces overall device complexity compared to having dedicated circuits for each voltage level, while still achieving reliable rapid voltage generation.
Data Source
AI summary
Provided herein is a voltage generating circuit including: a negative voltage pump configured to generate a first negative voltage; and a negative voltage regulator configured to generate a second negative voltage using the first negative voltage and output the second negative voltage through an output terminal. The negative voltage regulator includes a first amplifier circuit configured to be controlled by a voltage of the output terminal, and a voltage booster configured to increase a voltage of the output terminal depending on an output voltage of the first amplifier circuit.