Semiconductor Device Match Line Length Optimization
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Solution Overview
Problem
Existing TCAM devices require high power consumption to set the match line to a low potential for data mismatch operations, which is inefficient and increases energy costs.
Innovation Solution
A semiconductor device with a memory array divided into memory blocks that perform retrieval operations sequentially, utilizing shorter match lines for preceding blocks and longer ones for subsequent blocks, along with timing control units to manage search line driving based on match line lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the memory array is divided into multiple memory blocks with different match line lengths, then power consumption is reduced and search speed is improved, but device complexity increases
Solution Approach 1:
The memory array is divided into multiple memory blocks (first memory block, second memory block, etc.), each with different match line lengths. The first memory block has shorter match lines while subsequent blocks have longer match lines, allowing sequential search operations that reduce overall power consumption while maintaining search functionality.
Solution Approach 2:
Different match line lengths are assigned to different memory blocks based on their position in the sequential search sequence. The first memory block uses shorter match lines for faster initial search, while subsequent blocks use longer match lines appropriate for their role in the sequential search process, optimizing both speed and power consumption locally for each block.
2Speed
If match lines are made shorter for preceding memory blocks, then search speed is improved and power consumption is reduced, but timing control complexity increases
Solution Approach 1:
The timing control unit is configured to control the driving timing of search lines in advance based on the different match line lengths. For the first memory block with shorter match lines, search lines are driven earlier, while for subsequent memory blocks with longer match lines, search lines are driven later, ensuring proper timing without requiring complex real-time adjustments during operation.
3Loss of energy
If sequential search operations are performed across multiple memory blocks, then power consumption is reduced, but search time increases
Solution Approach 1:
The sequential search operation proceeds in periodic stages through different memory blocks. The timing control unit coordinates search line driving in a periodic sequence: first driving search lines for the first memory block, then subsequently driving search lines for the second memory block, and so on. This periodic action allows the system to complete searches across all blocks while managing power consumption efficiently and maintaining acceptable search times through optimized timing.
Data Source
AI summary
A semiconductor device includes a memory array having a plurality of associative memory cells arranged in a matrix form for storing entries. The memory array is divided into a plurality of memory blocks for sequentially performing a retrieval operation along a column direction, and further includes a plurality of match lines corresponding to the respective memory blocks and provided correspondingly to each memory cell row, a plurality of search lines corresponding to the respective memory blocks and provided correspondingly to each memory cell column, and a plurality of match amplifiers corresponding to the respective memory blocks and provided to the plurality of match lines. The match line provided correspondingly to the preceding memory block is set to become shorter than the match line provided correspondingly to the subsequent memory block. The memory array further includes a timing control unit for controlling timing for driving the search line of the subsequent memory block based on a length of the match line provided correspondingly to the preceding memory block.