VDD Generator Circuit Stabilization for NAND Flash Memory
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Solution Overview
Problem
Conventional NAND flash memory devices face challenges in stabilizing and efficiently generating internal power supply voltage (VDD) due to oscillations and delayed responses to changes in load conditions, which affect data read/write operations and overall system performance.
Innovation Solution
The semiconductor device incorporates a VDD generator circuit with a current mirror part, reference and monitor transistors, and capacitors to stabilize and quickly respond to changes in the internal power supply voltage, using a differential amplifier to adjust the output driver and minimize oscillations by feedback mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional voltage generation circuit is used, then the circuit structure is simple, but the internal power supply voltage oscillates and the response to load changes is delayed
Solution Approach 1:
The patent implements a feedback mechanism where a first capacitor connects the output part back to the current mirror part, and a second capacitor connects the output part to the reference transistor. This feedback loop continuously monitors the internal power supply voltage and adjusts the output driver accordingly, eliminating oscillations and improving stability without requiring a fundamentally complex circuit architecture.
Solution Approach 2:
The patent introduces capacitors as intermediary elements between different parts of the voltage generation circuit. The first capacitor acts as an intermediary between the output and current mirror parts, while the second capacitor intermediates between the output and reference transistor. These intermediaries smooth voltage fluctuations and improve response time to load changes.
2Speed
If the internal power supply voltage responds quickly to load changes, then the system performance improves, but voltage oscillations occur
Solution Approach 1:
The feedback mechanism continuously monitors voltage changes and provides real-time adjustment signals to the output driver. When load changes cause voltage fluctuations, the feedback loop detects these changes and immediately corrects them, achieving both fast response and stability by closing the control loop.
Solution Approach 2:
The capacitors are pre-configured in the circuit to anticipate and counteract voltage fluctuations before they manifest as oscillations. The first and second capacitors store energy and release it proactively when voltage changes are detected, preventing oscillatory behavior while maintaining rapid response to legitimate load changes.
3Reliability
If feedback mechanisms are added to reduce oscillations, then voltage stability improves, but the circuit complexity increases
Solution Approach 1:
The feedback mechanism is implemented using existing circuit components (capacitors connected to the output driver, current mirror part, and reference transistor) rather than adding entirely new feedback circuits. This approach provides the necessary feedback functionality with minimal additional complexity.
Solution Approach 2:
The capacitors in the circuit serve multiple functions: they provide feedback, filter voltage fluctuations, and improve response time. By making these components multi-functional, the patent achieves voltage stability without requiring dedicated feedback components that would increase circuit complexity.
Data Source
AI summary
A semiconductor device includes an input-part receiving a first voltage and an output-part outputing a second voltage. A current mirror part receives the first voltage. A reference voltage is supplied to a gate of a reference transistor. The reference transistor is electrically connected between the current-mirror part and a ground voltage. A monitor transistor includes a gate electrically connected to the second power-supply voltage, and is electrically connected between the current-mirror part and the ground voltage. A voltage-generation transistor includes a gate electrically connected to both the current-mirror part and the reference transistor. The voltage-generation transistor is electrically connected between the input-part and the output-part. A first capacitor including one end electrically connected to the output-part, and the other end electrically connected to both the current-mirror part and the reference transistor.