TCAM MTJ Bitcell Resistor Divider Read Disturb
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Solution Overview
Problem
Ternary content addressable memory (TCAM) systems using magnetic tunnel junction (MTJ) devices face significant challenges with read disturb, where bits unintentionally change states, leading to reduced reliability and accuracy in search operations.
Innovation Solution
The implementation of two MTJ devices with parallel coupled bi-directional resistive elements forms a resistor divider, shared series coupled bi-directional resistive elements, and the use of internal and external reference bitcells to improve read disturb immunity and enhance match line detection, allowing for accurate identification of bitcell states during search operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If MTJ devices are used to store bits in TCAM bitcells, then storage density is improved and power consumption is reduced, but read disturb becomes more severe causing bits to change states unintentionally
Solution Approach 1:
The patent divides the MTJ device into two separate MTJ devices within each bitcell, where each MTJ stores one bit of the ternary state. This segmentation allows independent control and reading of each MTJ, reducing the read disturb effect on the other MTJ when performing search operations.
Solution Approach 2:
The patent introduces additional circuitry including sense amplifiers and reference bitcells that act as intermediaries between the MTJ devices and the search operation. These intermediaries enable accurate detection of the ternary state without directly reading both MTJ devices simultaneously, thereby reducing read disturb.
2Use of energy by stationary object
If MTJ devices are used in TCAM bitcells, then power consumption is reduced, but read disturb causes unintentional state changes reducing search operation accuracy
Solution Approach 1:
By segmenting the storage function into two separate MTJ devices, the patent enables selective reading of one MTJ while keeping the other in a stable state, maintaining search accuracy without requiring high power to read both devices simultaneously.
Solution Approach 2:
The patent employs sense amplifiers and reference bitcells that provide feedback signals to accurately detect the state of the MTJ devices. This feedback mechanism ensures precise measurement of the ternary state even when reading operations are performed on individual MTJ devices, maintaining search accuracy with lower power consumption.
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
This configuration effectively prevents read disturb by limiting voltage stress on resistive elements and improves the detection of match and mismatch conditions, enhancing the overall reliability and accuracy of TCAM systems.
Implementation Method 1
magnetic tunnel junction devices may be used
Data Source
AI summary
A ternary content addressable memory (TCAM) cell is coupled to a first word line and a first match line and includes a first data storage portion coupled to a first search line, a second data storage portion coupled to a complement of the first search line, and a resistor divider portion including two resistive elements coupled in series with the first and second data storage portions of the first TCAM cell. The first and second data storage portions of the first TCAM cell are coupled to a first supply voltage and include two resistive elements coupled in parallel.