Hierarchical Wordline Driver Timing Control
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Solution Overview
Problem
As the degree of integration and storage capacity of memory devices increase, the resistance and parasitic capacitance of wordlines also increase, requiring a wordline driver with higher current-driving capacity to optimize performance, particularly in hierarchical wordline structures.
Innovation Solution
A wordline driver is designed with a pre-driver, transmission circuit, and sub-wordline driver to efficiently control the timings of wordline enable and disable signals, using a repeater for amplifying the enable signal and transmitting the disable signal without amplification, thereby reducing the number of logic gates and improving drive capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hierarchical wordline structure is adopted to optimize wordline length and improve memory device performance, then the drive capacity requirement increases due to increased resistance and parasitic capacitance, but the device complexity and power consumption increase
Solution Approach 1:
The wordline driver is divided into a pre-driver and a sub-wordline driver. The pre-driver generates control signals (WORDLINE_ENABLE and WORDLINE_DISABLE) based on selection signals and timing control signals, while the sub-wordline driver controls the voltage level of sub-wordlines. This segmentation allows independent optimization of each driver's function, reducing overall complexity while maintaining high drive capacity for the hierarchical wordline structure.
2Productivity
If a hierarchical wordline structure is adopted to optimize wordline length and improve memory device performance, then the drive capacity requirement increases due to increased resistance and parasitic capacitance, but the power consumption increases
Solution Approach 1:
The pre-driver performs preliminary action by generating the WORDLINE_ENABLE and WORDLINE_DISABLE control signals in advance based on timing control signals. This allows the sub-wordline driver to be controlled with precise timing, ensuring that power-consuming operations are minimized by activating sub-wordlines only when needed and keeping them active for optimized durations, thus reducing overall power consumption while maintaining high performance.
3Productivity
If the wordline enable signal and wordline disable signal timings are controlled independently, then the drive capacity and power consumption are improved, but the device complexity increases
Solution Approach 1:
Timing control signals serve as intermediaries between the pre-driver and the sub-wordline driver. The pre-driver uses these timing control signals to independently control the transition time points of WORDLINE_ENABLE and WORDLINE_DISABLE. This intermediary mechanism allows independent timing control without requiring complex direct control logic in the sub-wordline driver, thus improving drive capacity while managing complexity through the intermediary timing signals.
Data Source
AI summary
A wordline driver includes a pre-driver, a sub-wordline driver and a transmission circuit. The pre-driver generates a wordline enable signal and a wordline disable signal based on one or more selection signals, a decoded address signal, and one or more timing control signals. The transmission circuit transmits the wordline enable signal and the wordline disable signal. The sub-wordline driver controls a voltage level of the sub-wordline based on the wordline enable signal and the wordline disable signal that are transmitted by the transmission circuit. Therefore, driving capacity may be improved.