Flash Memory High Voltage Generating Circuit Feedback Control
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Solution Overview
Problem
NAND flash memory devices face challenges in accurately controlling the magnitude of program voltage during incremental step pulse programming, particularly for multi-level cells, where minor fluctuations can result in undesired threshold voltages and incorrect programming.
Innovation Solution
A high voltage generating circuit comprising a charge pump, voltage dividing circuit, comparing circuit, and clock controlling circuit, where the high voltage is fed-back as a switching voltage to stabilize and adjust the voltage dividing path, ensuring accurate control of the program voltage magnitude across successive program loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If incremental step pulse programming is used to program NAND flash memory cells, then programming flexibility and multi-level cell support are improved, but voltage magnitude control accuracy deteriorates due to fluctuations causing undesired threshold voltages
Solution Approach 1:
The patent implements a feedback mechanism where the generated high voltage is fed back to the control gate of the charge pump. This feedback loop allows the circuit to sense the actual voltage level and adjust the pumping clock signal accordingly, ensuring precise voltage magnitude control while maintaining the flexibility of incremental step pulse programming.
Solution Approach 2:
The patent replaces traditional external voltage control mechanisms with an integrated charge pump circuit that generates and self-regulates the program voltage. This substitution eliminates external mechanical or manual voltage adjustment, providing more stable and accurate voltage control through electronic feedback within the memory device itself.
2Power
If high voltage is generated using a charge pump, then program voltage magnitude is improved, but voltage stability deteriorates due to overshooting and fluctuations
Solution Approach 1:
The control gate of the charge pump receives feedback from the generated high voltage, creating a closed-loop control system. This feedback mechanism detects voltage deviations and adjusts the pumping clock signal in real-time, preventing overshooting and maintaining stable voltage levels throughout the programming operation.
Solution Approach 2:
The patent employs dynamic control of the pumping clock signal based on feedback voltage levels. The clock signal characteristics (frequency, duty cycle) are adjusted dynamically during operation to maintain optimal voltage stability, allowing the system to adapt to changing conditions while preventing oscillations and overshooting.
3Adaptability or versatility
If program voltage magnitude is increased for multi-level cell programming, then programming capability is improved, but power consumption increases
Solution Approach 1:
The feedback mechanism enables precise control of the charge pump operation, allowing the circuit to generate the necessary high voltage for multi-level cell programming only when needed. By monitoring the actual voltage level and adjusting the pumping clock signal accordingly, the system avoids excessive power consumption while maintaining the capability to program multi-level cells.
Solution Approach 2:
The charge pump operates in periodic cycles synchronized with the incremental step pulse programming sequence. The pumping clock signal activates the charge pump only during required voltage generation phases, allowing power consumption to be reduced through periodic operation rather than continuous high-power generation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution prevents overshooting and stabilizes the program voltage, reducing power consumption and improving programming accuracy by maintaining consistent switching voltage and enable signals throughout each program loop, thereby enhancing the reliability of NAND flash memory devices.
Implementation Method 1
a charge pump (10) adapted to generate a high voltage in response to a pumping clock signal
Data Source
AI summary
In a flash memory device, a high voltage generating circuit generates a high voltage and receives the high voltage as a switching voltage for controlling a voltage dividing circuit.