Content Addressable Memory Self-Test for Match Line Verification
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Solution Overview
Problem
Content addressable memories face challenges with overlarge area and complex configurations due to increased storage capacity and reduced device dimensions, necessitating an efficient self-test mechanism for match lines.
Innovation Solution
A content addressable memory circuit with internal and external test pattern generation and comparison circuits, along with a self-test control circuit, to perform compact and aligned self-tests, reducing routing area and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If storage amount is increased and device dimension is reduced, then memory capacity and integration are improved, but self-test component area and configuration complexity become overlarge and over-complex
Solution Approach 1:
The patent merges the test pattern generation circuit and comparison circuit into the content addressable memory circuit itself, making them integrated components rather than separate external circuits. This integration reduces the overall area occupied by test components and simplifies the configuration by eliminating the need for complex external test equipment and routing.
Solution Approach 2:
The content addressable memory circuit performs self-testing using internally generated test patterns and comparison signals. The memory circuit generates test data and address signals internally, compares them with stored data, and produces test results without requiring external test apparatus, thereby reducing external complexity and enabling compact self-test implementation.
2Quantity of substance
If storage amount is increased and device dimension is reduced, then memory capacity and integration are improved, but self-test component area becomes overlarge
Solution Approach 1:
The test pattern generation circuit and comparison circuit are merged within the content addressable memory circuit boundaries, sharing the same physical space and routing resources. This integration ensures that the area occupied by test components is included in the memory circuit area rather than adding extra area outside the memory device.
Solution Approach 2:
The patent utilizes the time dimension by generating test patterns sequentially through shift registers that shift test data through multiple stages. This temporal sequencing allows the same physical hardware to perform multiple test functions in sequence, reducing the need for parallel hardware components and thereby minimizing the overall area required for self-testing.
Data Source
AI summary
The present disclosure discloses a content addressable memory apparatus. A self-test control circuit generates self-test driving signals and control an external test pattern generation circuit generates search data and an address signal. A content addressable memory circuit includes a memory circuit, an internal test pattern generation circuit and an internal comparison circuit. The memory circuit receives the search data and the address signal from the external test pattern generation circuit to perform search operation to generate actual match signals corresponding to the match lines. The internal test pattern generation circuit receives the self-test driving signals from the self-test control circuit to generate expected match signals. The internal comparison circuit receives and compares the actual match signals and the expected match signals to generate match comparison results such that the self-test control circuit receives the match comparison results and performs verification accordingly.