Internal Supply Voltage Generation Circuit for DRAM Cell Plate Stability
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Solution Overview
Problem
As DRAM devices become highly integrated, the cell plate voltage generation in semiconductor memory devices faces instability and prolonged setup times due to increased memory cells, requiring a more robust and stable internal supply voltage generation circuit.
Innovation Solution
The proposed solution involves an internal supply voltage generation circuit with two driving circuits and a resistive device, where each driving circuit maintains an output voltage between specific reference voltages, and the resistive device is formed by a parasitic resistor in a transmission line, ensuring stability and short setup times for the cell plate voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of memory cells is increased for high integration, then the memory capacity is improved, but the cell plate voltage becomes unstable and setup time lengthens
Solution Approach 1:
The voltage generation function is divided into two separate driving circuits (first driving circuit and second driving circuit), each responsible for generating voltage within a specific range. This segmentation allows each circuit to be optimized for its specific voltage range, improving overall voltage stability and reducing setup time even as memory capacity increases
Solution Approach 2:
The patent changes the voltage generation parameters by using two different sets of reference voltages (first and second reference voltages for the first driving circuit, third and fourth reference voltages for the second driving circuit). This parameter differentiation enables precise control over the cell plate voltage across different operating conditions, maintaining stability in high-density memory configurations
2Quantity of substance
If the number of memory cells is increased for high integration, then the memory capacity is improved, but the setup time becomes longer
Solution Approach 1:
The voltage generation is segmented into two parallel driving circuits that can operate simultaneously to establish different voltage ranges. This parallel segmentation reduces the sequential setup time required to reach stable operating voltages, allowing high-capacity memory devices to initialize faster
Solution Approach 2:
The driving circuits are designed to preemptively establish voltage within target ranges using predetermined reference voltages. This preliminary voltage establishment reduces the time required for voltage stabilization during memory operation, addressing the setup time issue in high-density configurations
3Device complexity
If a conventional voltage generation circuit is used, then the circuit structure is simple, but the internal supply voltage becomes unstable during setup
Solution Approach 1:
The voltage generation is divided into two independent driving circuits, each with its own reference voltages and control logic. This segmentation provides redundant voltage generation paths that stabilize the internal supply voltage during setup, preventing the instability issues present in conventional single-circuit designs
Solution Approach 2:
Each driving circuit receives feedback from its respective node (first feedback voltage from first node, second feedback voltage from second node) and adjusts its output accordingly. This feedback mechanism ensures stable voltage generation by continuously monitoring and correcting voltage deviations, addressing the stability issue while maintaining reasonable circuit complexity
Data Source
AI summary
An internal supply voltage generation circuit includes first and second driving circuits and a resistive device. The first driving circuit receives a feedback voltage from a first node and generates a first output voltage based on first and second reference voltages to provide the first output voltage to the first node. The first output voltage is maintained between the first and second reference voltages. The second driving circuit receives a feedback voltage from a second node voltage and generates a second output voltage based on third and fourth reference voltages to provide the second output voltage to the second node. The second output voltage is maintained between the third and fourth reference voltages, and the second output voltage of the second node is provided as an internal supply voltage. The resistive device is coupled between the first and second nodes.