Ternary Content Addressable Memory Cell Integration
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Solution Overview
Problem
Conventional ternary content addressable memory (TCAM) devices face challenges in increasing memory capacitance and integration, with a lack of concrete layouts for TCAM cells, which hinders their performance and efficiency in high-speed operations.
Innovation Solution
A semiconductor memory device configuration featuring memory cells arranged in rows and columns, with each cell capable of holding two bits, utilizing a bit line pair and word lines for data storage and search operations, and a logical operation cell for matching search data, while reducing the number of interconnection layers to enhance integration and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional TCAM cell configuration is used, then device complexity is reduced, but memory capacitance and integration are insufficient
Solution Approach 1:
The memory cell is segmented into multiple functional components: first cell (546), second cell (548), comparing circuit (550), and logical operation cell (552). Each component performs a specific function, allowing the system to achieve high integration and capacitance while maintaining manageable complexity through functional decomposition.
Solution Approach 2:
The patent implements a nested structure where the logical operation cell (552) is placed adjacent to and integrates with the first and second cells (546, 548). The comparing circuit (550) is also integrated within the same cell structure, creating a compact nested arrangement that increases memory capacitance without proportionally increasing device complexity.
2Productivity
If conventional TCAM layout is used, then manufacturing simplicity is maintained, but integration degree and speed are limited
Solution Approach 1:
The patent merges multiple functions into a single integrated cell structure. The first cell (546), second cell (548), comparing circuit (550), and logical operation cell (552) are combined in a compact arrangement shared by common bit line pairs (BIT, BITN) and word lines (WL1, WL2). This merging increases integration degree while maintaining manufacturing feasibility through standardized semiconductor processes.
3Ease of operation
If more interconnection layers are used, then connectivity is improved, but manufacturing cost and power consumption increase
Solution Approach 1:
The bit line pairs (BIT, BITN) and word lines (WL1, WL2) serve multiple functions: they provide data input paths, enable comparison operations, and support logical operations within the same physical structures. This multi-functionality reduces the need for additional dedicated interconnection layers, thereby reducing power consumption while maintaining connectivity.
Data Source
AI summary
A TCAM (ternary content addressable memory) cell array is provided with a search input node into which one bit of search data is inputted, a plurality of data input nodes into which a bit corresponding to one bit of search data is inputted, and a plurality of memory cells arranged in rows and columns. Each of the plurality of memory cells further includes a first cell storing one bit of said storage data, and a logical operation cell determining whether or not said search data and storage data match. A gate of a transistor forming each of a plurality of memory cells extends along the direction of said rows. Each of a plurality of wells in the region where the memory array is formed is formed so as to continue to a corresponding well of an adjacent memory cell in the direction of said columns.