Internal Voltage Generation Circuit for Semiconductor Memory
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Solution Overview
Problem
The Widlar-type internal voltage generation circuit requires a large circuit area and faces challenges in generating stable internal voltages due to the need for a reset operation time, which can lead to instability when the enable signal is reactivated before the reset time is guaranteed.
Innovation Solution
An internal voltage generation circuit that includes an enable control circuit to limit the activation time of the enable signal after a reset time, a start-up control circuit to perform a reset operation and generate a start-up signal, a reference voltage generation circuit, a current generation circuit, and multiple voltage generation circuits to generate internal voltages based on reference currents, ensuring stable operation and reduced circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Widlar-type internal voltage generation circuit is used to generate stable internal voltage, then voltage stability is improved, but circuit area increases
Solution Approach 1:
The circuit is divided into functional modules: voltage generation circuit, start-up circuit, and enable control circuit. Each module performs a specific function, allowing for optimized area usage while maintaining stability. The segmentation enables the enable control circuit to manage the start-up timing independently, reducing the overall area requirement compared to a monolithic Widlar circuit.
Solution Approach 2:
The enable control circuit performs preliminary action by controlling the enable signal to ensure the start-up circuit completes its reset operation before the voltage generation circuit is activated. This preliminary control of the enable signal timing prevents instability without requiring additional area for reset management, as the enable signal itself is used to coordinate the start-up sequence.
2Reliability
If a Widlar-type internal voltage generation circuit is used to generate stable internal voltage, then voltage stability is improved, but device complexity increases
Solution Approach 1:
The enable control circuit merges the functions of enable signal generation and start-up control into a single circuit block. By combining these functions and using the enable signal to control both the start-up sequence and the voltage generation activation, the circuit complexity is reduced compared to having separate control circuits for each function.
Solution Approach 2:
The enable signal serves multiple functions: it controls the start-up circuit operation, manages the reset timing, and activates the voltage generation circuit. This multi-functionality reduces the need for additional control signals and circuits, thereby reducing overall device complexity while maintaining voltage stability.
3Productivity
If the enable signal is reactivated before reset time is completed, then productivity is improved, but voltage stability deteriorates
Solution Approach 1:
The enable control circuit uses feedback from the enable signal timing to control the start-up circuit. The circuit monitors the enable signal activation and ensures the start-up operation completes before voltage generation begins. This feedback mechanism allows rapid response to enable signals while preventing instability by ensuring proper start-up sequencing.
Solution Approach 2:
The enable control circuit dynamically adjusts the activation timing of the voltage generation circuit based on the completion of the start-up operation. Rather than using a fixed delay, the circuit responds dynamically to the actual start-up completion time, allowing maximum productivity while ensuring voltage stability is maintained through proper sequencing.
Data Source
AI summary
An internal voltage generation circuit includes an enable control circuit configured to generate a final enable signal by limiting an activation time point of an enable signal to a point in time after a reset time, after the enable signal is inactivated. The internal voltage generation circuit also includes a start-up control circuit configured to perform a reset operation during the reset time and generate a start-up signal based on the final enable signal, a reference voltage generation circuit configured to generate a reference voltage based on the start-up signal, a current generation circuit configured to generate a reference current based on the reference voltage, and a voltage generation circuit configured to generate an internal voltage based on the reference current.