In-Memory Search Using Two-Stage Voltage Read
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Solution Overview
Problem
Existing memory devices require a large circuit area and high power consumption due to the need for reference memory cells in ternary content addressable memory (TCAM) for data search operations, leading to inefficiencies in storage density and utilization.
Innovation Solution
A two-stage in-memory search method that uses a single non-volatile memory cell to perform data searches by applying different voltages and reading currents, eliminating the need for a reference memory cell and reducing circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference memory cell is used to complete the search operation, then the search function can be implemented, but the circuit area increases and storage density decreases
Solution Approach 1:
The patent extracts and eliminates the reference memory cell from the TCAM structure. By using a two-stage read operation where the first stage reads data at a first voltage level and the second stage reads data at a second voltage level, the system determines search results without requiring a separate reference memory cell, thus reducing circuit area while maintaining search functionality
Solution Approach 2:
The patent makes the single memory cell perform multiple functions by using it for both data storage and reference comparison. The same memory cell that stores the data is also used to provide reference information through the two-stage voltage application, eliminating the need for a dedicated reference memory cell and improving space utilization
2Reliability
If a reference memory cell is used for data search, then search operation can be completed, but power consumption increases
Solution Approach 1:
By removing the reference memory cell from the system, the patent eliminates the additional power consumption that would be required to operate and maintain the extra memory cell and its associated circuitry, while still achieving reliable search operations through the two-stage voltage reading method
3Area of stationary object
If two-stage read operation is used without reference memory cell, then circuit area is reduced, but measurement precision of search result may be affected
Solution Approach 1:
The patent changes the voltage parameter applied to the memory cell in two distinct stages. The first stage uses a first voltage level to read data, and the second stage uses a second voltage level to read reference information. This parameter change enables the system to achieve both reduced circuit area and maintained search accuracy by utilizing the voltage-dependent characteristics of the memory cell
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 approach increases memory cell utilization, enhances search capacity, and reduces the required circuit area, thereby improving efficiency and reducing costs.
Implementation Method 1
a first voltage VSL1 or a second voltage VSL2 is provided to a word line WL of at least one target memory cell according to a logic status of searched data
Implementation Method 2
a first current I1 is read... a second current I2 is read
Data Source
AI summary
A memory device and an in-memory search method thereof are provided. The in-memory search method includes: providing, in a first stage, a first voltage or a second voltage to a word line of at least one target memory cell according to a logical status of searched data, and reading a first current; providing, in a second stage, a third voltage or a fourth voltage to the word line of the at least one target memory cell according to the logical status of the searched data, and reading a second current; and obtaining a search result according to a difference between the second current and the first current.