Multi-Stage Content Addressable Memory Power Management
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Solution Overview
Problem
Content-addressable memory (CAM) devices experience high power consumption and peak currents due to their parallel design, limiting their applicability in various applications, despite existing techniques that partition memory architecture into stages to reduce power consumption.
Innovation Solution
A multi-stage content addressable memory device is designed with distinct segments and power regimes for each stage, where the first segment operates at a lower power and voltage for frequent comparisons, and subsequent segments at higher power and voltage for conditional comparisons, allowing for dynamic power management and reduced peak currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If CAM devices use parallel design for search operations, then search speed is improved, but power consumption increases
Solution Approach 1:
The CAM device is divided into multiple segments, each handling a portion of the search operation. Match lines are segmented and processed in stages, allowing the parallel search capability to be maintained while reducing the power consumption of any single segment by limiting the number of active comparators at any given time.
Solution Approach 2:
The CAM device dynamically activates different segments based on the search requirements. By controlling which segments are active during each clock cycle, the system can maintain high search speed when needed while reducing power consumption during operations that require fewer comparisons, creating a dynamic balance between speed and power usage.
2Productivity
If CAM devices operate in single clock cycle for entire content search, then search efficiency is improved, but peak current increases
Solution Approach 1:
The search operation is segmented into multiple stages processed across different clock cycles. Instead of activating all comparators simultaneously in a single clock cycle, the device processes segments sequentially through multiple cycles, maintaining overall search efficiency while distributing the peak current demand across time, thereby reducing the maximum instantaneous current draw.
Solution Approach 2:
The CAM device uses periodic clock cycles to activate different segments in a structured sequence. By organizing the search into periodic stages where different segment groups are activated in alternating clock cycles, the system maintains productivity through systematic progression while reducing peak current by ensuring not all segments are active simultaneously.
3Use of energy by moving object
If CAM devices partition memory into stages, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The memory is partitioned into segments with corresponding match line segments and comparator groups. While this segmentation reduces power consumption by enabling selective activation, it inherently increases device complexity. The patent manages this complexity through systematic organization of the segmented components and control logic that coordinates their operation across multiple clock cycles.
Solution Approach 2:
The segmented architecture introduces dynamic control mechanisms to manage the increased complexity. By using dynamic segmentation where different segment configurations can be activated based on operational requirements, the system balances the added architectural complexity with flexible power management capabilities, allowing the complexity to be justified by the power savings in specific operating conditions.
Data Source
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AI summary
Multi-stage content addressable memory devices are described. Some embodiments relate to memory devices including a plurality of rows of memory cells, multiple match lines and multiple pre-charge circuits. A first row of the plurality of rows includes a first segment and a second segment. The first segment may include a first subset of the memory cells of the first row and the second segment may include a second subset of the memory cells of the first row. The first match line is coupled to the memory cells of the first subset, and the second match line is coupled to the memory cells of the second subset. The first pre-charge circuit is configured to pre-charge the first match line to a first pre-charge voltage, and the second pre-charge circuit is configured to pre-charge the second match line to a second pre-charge voltage different from (e.g., greater than) the first pre-charge voltage.