Ternary Content Addressable Memory Switch Set Design
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Solution Overview
Problem
Conventional ternary content addressable memory (TCAM) designs require a large number of circuit components, which increases complexity and cost, while also not efficiently managing search operations for match, miss, and don't care conditions.
Innovation Solution
A TCAM design utilizing a minimal set of circuit components, including first and second memory cells and a switch set, which adjusts the resistance between a match line and a reference ground based on search signals to determine search results, incorporating a pull-up circuit for voltage management during pre-charge and evaluation phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional TCAM designs are used, then search functionality is provided, but the number of circuit components increases complexity and cost
Solution Approach 1:
The patent merges multiple functionality into a single switch set that handles match, miss, and don't care conditions. The switch set integrates the control logic for different search operations (search 0, search 1, search don't care) into one component structure, eliminating the need for separate circuit paths for each condition and thereby reducing overall device complexity while maintaining reliable search operation management.
Solution Approach 2:
The switch set is designed as a universal component that performs multiple functions: it controls the match line for match conditions, handles miss conditions, and manages don't care conditions. This multi-functional design eliminates the need for dedicated circuits for each search operation type, reducing the number of circuit components while ensuring reliable management of all search operations.
2Area of stationary object
If more circuit components are used, then search operation management is improved, but circuit area increases
Solution Approach 1:
The patent combines multiple search operation controls into a single switch set structure, reducing the total circuit area occupied by separate control circuits for match, miss, and don't care conditions. This merged structure maintains ease of operation by providing unified control mechanisms while occupying less silicon area compared to conventional designs with separate circuits for each function.
Solution Approach 2:
The patent extracts the essential control functionality into a minimal set of circuit components centered around the switch set. By taking out only the necessary control elements and eliminating redundant circuits, the design achieves compact circuit area while preserving the ease of managing different search operations through the streamlined switch set interface.
3Ease of manufacture
If conventional TCAM designs are used, then search functionality is provided, but costs increase
Solution Approach 1:
The patent merges multiple control functions into a single switch set, reducing the total number of transistors required compared to conventional TCAM designs that use separate circuits for each search operation. This consolidation simplifies the manufacturing process and reduces component count, thereby lowering manufacturing costs while maintaining full search functionality for match, miss, and don't care conditions.
Solution Approach 2:
The patent employs a minimalist circuit architecture using a small number of transistors in the switch set, replacing complex conventional circuits with a simpler, more cost-effective design. This approach uses fewer expensive transistor components while achieving the same functional outcomes, making the TCAM more economical to manufacture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design reduces the number of transistors required for each encoded bit, saving circuit area and reducing costs while effectively managing search operations for match, miss, and don't care conditions by adjusting voltage levels on the match line.
Implementation Method 1
The switch set adjusts a resistance of a path between the match line and the reference ground according to a voltage on the common end and a third search signal
Implementation Method 2
the pull-up circuit pulls up a voltage level of the match line to the first logic level during the pre-charge phase before each of the search 0, search 1, and search don't operations being operated
Data Source
AI summary
A ternary content addressable memory includes at least one first memory cell, at least one second memory cell and at least one switch set. The first memory cell receives a first search signal, determines whether to send first stored data to a common end or not according to the first search signal. The second memory cell receives a second search signal, determines whether to send second stored data to the common end or not according to the second search signal. The switch set adjusts a resistance of a path between the match line and the reference ground according to a voltage on the common end and a third search signal.