Content Addressable Memory Segmentation for Signal Delay
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Solution Overview
Problem
Conventional content addressable memories face challenges in achieving high-speed operation due to signal propagation delays caused by increased wiring capacitance as the number of memory cells grows, making it difficult to control timing delays effectively.
Innovation Solution
The content addressable memory design includes match lines, precharge units, memory cells, match amplifiers, and a search data transfer unit, where search data is transferred to memory cells in an arrangement order from the side far away from match amplifiers, allowing for logic level detection without considering delay times of match lines, enabling higher frequency operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of memory cells is increased to achieve high integration and greater capacity, then memory capacity is improved, but signal propagation delay increases due to increased wiring capacitance
Solution Approach 1:
The patent divides the memory array into multiple blocks, each with its own dedicated sense amplifier and control circuitry. This segmentation allows independent operation of each block, reducing the total capacitance that any single signal line must drive and thereby reducing propagation delay while maintaining high overall capacity
Solution Approach 2:
The patent introduces a third dimension to the memory architecture by stacking multiple memory blocks vertically or arranging them in a three-dimensional configuration. This dimensional change increases storage capacity without proportionally increasing the wiring capacitance in the planar direction, thus mitigating signal propagation delay
2Area of stationary object
If more memory cells are coupled to each wiring to increase integration density, then device area efficiency is improved, but wiring capacitance increases causing slower operation
Solution Approach 1:
The memory structure is divided into multiple segments or blocks, each with reduced cell counts per wiring. This segmentation reduces the capacitance load on each wiring while achieving high overall density through parallel organization of multiple segments, thereby maintaining fast operation speed
Solution Approach 2:
Different regions or blocks of the memory array are optimized with locally adapted wiring configurations and cell densities. This allows certain areas to have higher density while others maintain lower capacitance, achieving overall high integration without uniformly sacrificing speed across the entire device
Data Source
AI summary
A content addressable memory includes a memory array having a plurality of match lines extending in a first direction, a plurality of search lines extending in a second direction perpendicular to the first direction, and a plurality of memory cells, each disposed at points where the match lines and the search lines intersect. The content addressable memory also includes a plurality of search line drivers, each of the search line drivers being provided to drive the search lines based on search data; a search control circuit generating a search line enable signal, and including a first and a second transistor, the first transistor) for output the search line enable signal and the second transistor for receiving the search line enable signal; and a control signal wiring coupled to the search control circuit and transmitting the search line enable signal to each of the search line drivers.