Variable Word Line Pulse Widths for Low-Power Memory Reads
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Solution Overview
Problem
Conventional memory devices consume excessive power due to uniformly long word line pulse widths, which are necessary to ensure accurate read operations across memory cells with varying bit line lengths, leading to inefficient power usage.
Innovation Solution
The memory device generates word line signals with varying pulse widths tailored to the specific bit line lengths of each memory cell, reducing power consumption by ensuring only the necessary duration for the read margin to develop on each bit line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniformly long word line pulse widths are used to ensure accurate read operations across all memory cells, then read accuracy is maintained, but power consumption increases excessively
Solution Approach 1:
The patent applies local quality by customizing the word line pulse width for each memory cell based on its specific bit line length. Instead of using a uniform pulse width for all cells, the system tailors the pulse duration to match the RC characteristics of each individual bit line, ensuring that each cell receives exactly the amount of time needed for accurate reading without excess.
Solution Approach 2:
The patent implements dynamics by making the word line pulse width variable rather than static. The pulse width dynamically adjusts based on the bit line length and RC characteristics of each memory cell, allowing the system to optimize power consumption while maintaining read accuracy across cells with varying electrical characteristics.
2Reliability
If uniformly long word line pulse widths are applied to all memory cells, then read operations are reliable, but power usage becomes inefficient
Solution Approach 1:
The patent applies parameter changes by modifying the pulse width parameter of the word line signal based on the specific RC characteristics of each memory cell's bit line. This allows the system to change the temporal parameter dynamically, ensuring that each cell receives the minimum necessary pulse duration for reliable reading, thereby reducing unnecessary energy loss.
3Reliability
If word line pulse widths are extended to accommodate the longest bit lines, then all memory cells can be read accurately, but power consumption increases for cells with shorter bit lines
Solution Approach 1:
The patent resolves this contradiction by applying local quality - each memory cell receives a word line pulse width specifically matched to its bit line length. Cells with short bit lines receive shorter pulses, while cells with long bit lines receive longer pulses, ensuring that no cell receives more time than necessary, thus eliminating the power waste that occurs when uniform long pulses are applied to all cells.
Data Source
AI summary
A memory device includes a plurality of memory cells, a plurality of word lines, and a word line driver. The word lines are respectively coupled to the memory cells. The word line driver is configured to respectively drive the word lines with word line signals that have varying pulse widths.