Parallel Test Apparatus for Memory Module Rank Testing
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Solution Overview
Problem
Conventional test methods for semiconductor memory devices, such as DRAMs, face challenges in accurately detecting defective parts and locating them due to increased storage capacities and the complexity of dual in-line memory modules, leading to longer test times and higher costs.
Innovation Solution
A memory module with a parallel test apparatus that generates parity data during write operations and transmits it as read data, allowing simultaneous testing of multiple ranks by controlling write and read operations in a parallel test mode, using XOR gates and multiplexers to identify defective ranks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional test methods are used for increased storage capacity DIMMs, then test accuracy may be maintained, but test time and test cost increase significantly
Solution Approach 1:
The memory module is divided into multiple ranks (first rank, second rank, etc.), each with its own parallel test apparatus. This segmentation allows independent parallel testing of each rank, enabling simultaneous testing of multiple memory structures without interfering with each other, thus reducing overall test time while maintaining detection accuracy for each segment
Solution Approach 2:
Multiple test operations are merged into a single parallel test framework where multiple ranks are tested simultaneously using shared control signals and coordinated test cycles. The test controller merges the test sequences of different ranks to execute them in parallel, achieving time compression while preserving the ability to detect defects in each rank
2Measurement precision
If conventional test methods are used for increased storage capacity DIMMs, then test accuracy may be maintained, but test cost increases
Solution Approach 1:
The parallel test apparatus is designed with universal components that can test multiple ranks using the same hardware resources. The test controller, signal lines, and control logic are configured to handle multiple ranks simultaneously, making the test system multi-functional rather than requiring separate dedicated test equipment for each rank, thereby reducing test cost
Solution Approach 2:
The test structure is replicated across multiple ranks where each rank has a corresponding parallel test apparatus that mirrors the test logic and control mechanisms. This copying approach allows standardized test procedures to be applied uniformly across all ranks, reducing development and implementation costs while maintaining consistent detection accuracy
3Loss of time
If various conventional test methods with reduced test time are used, then test time is reduced, but the ability to accurately detect defective parts and locations deteriorates
Solution Approach 1:
The parallel test apparatus incorporates feedback mechanisms where test results from each rank are independently captured and analyzed. The test controller receives feedback signals from each rank's test apparatus, allowing real-time monitoring and identification of defective parts and their locations across multiple ranks, ensuring high detection accuracy even while testing in parallel
Solution Approach 2:
The invention replaces sequential mechanical testing operations with parallel electronic test operations. By using electronic control signals and digital logic to coordinate simultaneous testing of multiple ranks, the system achieves time reduction without sacrificing detection capability, as electronic parallel processing maintains signal integrity and measurement precision
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 reduces test time and cost by enabling efficient simultaneous testing of multiple ranks, maximizing the number of DRAMs tested while accurately determining whether each rank is passed or failed.
Implementation Method 1
The parallel test apparatus may include at least one XOR gate configured to generate the first parity data for the write data during the write operation and generate the second parity data for the first data during the read operation
Data Source
AI summary
A memory module including a plurality of ranks. Each of the ranks includes a parallel test apparatus for simultaneous testing and a parallel test control unit. In response to a parallel test mode control signal, the parallel test apparatus generates first parity data for write data including a plurality of bits and generating first data obtained by replacing a bit value of at least one bit of the plurality of bits of the write data with the first parity data during a write operation, and generates second parity data for the first data and transmitting the second parity data as read data during a read operation. The parallel test control unit controls the write operation and the read operation in a parallel test mode by generating the parallel test mode control signal. Combinations of read data from the plurality of ranks correspond to different bits of the write data.