Base-3 CAM Cell Storage Density and Power Optimization
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Solution Overview
Problem
Content addressable memory (CAM) devices, particularly quaternary CAM cells, do not fully utilize their storage capacity as they only use three out of four possible states, leading to suboptimal data storage density and increased power consumption.
Innovation Solution
Implementing a base-3 numeral system in CAM cells, allowing each cell to store a trit (base-3 digit) and utilizing all four possible states, thereby increasing data storage density and reducing power consumption by optimizing the configuration of match lines and comparand lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If quaternary CAM cells use only three out of four possible states, then the device complexity is reduced and ease of operation is improved, but data storage density decreases and power consumption increases
Solution Approach 1:
The patent changes the fundamental parameter of data representation from binary (base-2) to ternary (base-3), allowing each CAM cell to store one of three values (0, 1, or don't-care) instead of requiring two bits. This parameter change enables full utilization of the four possible states in quaternary CAM cells, achieving 406% increase in storage capacity while reducing power consumption by 14% through optimized match line and comparand line configurations.
2Quantity of substance
If quaternary CAM cells use only three out of four possible states, then manufacturing and operation become simpler, but the storage capacity is underutilized
Solution Approach 1:
The patent makes the CAM cell structure universal by designing it to handle three distinct data values (0, 1, and don't-care) within a single cell architecture. The match line logic is designed to universally accept any of the three stored values and compare them against input data, eliminating the need for separate circuitry for each state and achieving full utilization of all four possible states in quaternary CAM cells.
Solution Approach 2:
Instead of using two bits to represent three values (leaving one state unused), the patent inverts the approach by using a single ternary digit to represent three values, thereby utilizing all four possible states of the quaternary cell. This inversion of the representation method maximizes storage capacity while simplifying the cell structure.
3Quantity of substance
If more CAM cells are used to increase storage capacity, then data storage density improves, but power consumption and device complexity increase
Solution Approach 1:
The patent merges multiple binary CAM cells into a single ternary CAM cell by combining the functionality of multiple cells into one. A single ternary cell can store one of three values, effectively replacing what would traditionally require multiple binary cells, thereby increasing storage density while reducing the total number of cells and associated power consumption.
Solution Approach 2:
The patent transitions from a two-dimensional binary representation (0 or 1) to a three-dimensional ternary representation (0, 1, or don't-care), adding an extra dimension of data storage capability. This dimensional change allows each cell to store more information, increasing storage capacity without proportionally increasing the number of cells or power consumption.
Data Source
AI summary
A CAM cell is disclosed that can be selectively configured to store either base-2 data words or base-3 data words. When configured to store base-3 data words, the quaternary CAM cell compares 3 comparand bits representative of a base-3 comparand value with the base-3 data value stored in the CAM cell. Storing base-3 data words in such CAM cells increases the data storage density of associated CAM arrays.