CAM Power Cut-Off Circuit for Reduced Energy Use
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Solution Overview
Problem
Conventional content-addressable memory (CAM) systems consume high power due to the need to keep the entire CAM array operational for high-speed search results, making them expensive and inefficient.
Innovation Solution
A power cut-off circuit is integrated with the valid bit cell to isolate the sense voltage from the matchline when an invalid validity state is stored, reducing voltage contention and overall power consumption, while maintaining valid bit cell functionality without additional circuitry or thermal design considerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the entire CAM array is kept operational to provide high-speed search results, then search speed is improved, but power consumption increases
Solution Approach 1:
The patent divides the CAM array into multiple banks or segments, allowing selective activation of only those segments needed for the current search operation. This segmentation enables the system to maintain high search speed in active segments while reducing power consumption by keeping inactive segments in a low-power state.
Solution Approach 2:
The patent implements dynamic power management by adjusting the operational state of CAM segments based on real-time search requirements. The system dynamically activates or deactivates specific CAM banks, matchlines, or bit cells depending on the search pattern and data set being processed, thereby optimizing the balance between search speed and power consumption.
2Speed
If the entire CAM array is powered for high-speed search, then search functionality is maintained, but on-chip space increases
Solution Approach 1:
By segmenting the CAM array into multiple independent banks, the patent enables spatial reuse of CAM resources. Different banks can be activated for different search operations, allowing the system to maintain high search speed capability while using less total on-chip space compared to a fully operational single-array design.
Solution Approach 2:
The patent makes CAM banks multi-functional by allowing them to be selectively activated for different search operations. A single CAM bank can serve multiple search functions by being dynamically enabled or disabled, reducing the need for dedicated CAM arrays for each function and thereby reducing overall on-chip space requirements.
3Use of energy by moving object
If additional circuitry is added to reduce power consumption, then power efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges the power management functionality with the existing valid bit cell circuitry. By integrating the power cut-off function into the valid bit cell that already exists in each CAM entry, the system achieves power reduction without adding separate dedicated power management circuits, thereby avoiding increased device complexity.
Solution Approach 2:
The valid bit cell is given multiple functions: it not only tracks the validity of CAM entries but also controls the power state of associated circuitry. This multi-functionality eliminates the need for separate power management circuits, maintaining device simplicity while improving power efficiency.
Data Source
AI summary
According to one disclosed embodiment, a content-addressable memory (CAM) system configured for reduced power consumption includes a sensing circuit utilized to apply a sense voltage to a matchline of the CAM system, a valid bit cell coupled to the matchline, and a power cut-off circuit configured to isolate the sense voltage from the matchline when an invalid validity state is stored in the valid bit cell, thereby reducing power consumption by the CAM system. In one embodiment, the power cut-off circuit isolates the sense voltage from the matchline by decoupling the sensing circuit from a control signal when an invalid validity state is stored in the valid bit cell.