Memory Interface Built-In Self-Test Circuitry
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Solution Overview
Problem
Current memory test equipment struggles to keep pace with increasing memory device frequencies, leading to inefficiencies and soaring costs due to the need for external test equipment and specialized arrangements for high-speed IO testing.
Innovation Solution
A memory interface circuitry with built-in self-test capabilities, comprising a clock generator, state machine, data pattern generator, I/O interface, write register, and comparator, which generates and compares pre-defined data patterns to verify I/O interface operations without external equipment, using a high-speed clock for testing while maintaining a low-speed command path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If external test equipment is used to test memory devices, then testing can be performed, but the test equipment cannot keep pace with increasing memory operating frequencies and test costs skyrocket
Solution Approach 1:
The memory device performs self-testing through built-in test circuitry that generates test patterns, applies them to the I/O interface, and verifies results internally. This eliminates the need for external test equipment to generate test signals, allowing the device to test itself at its full operating speed without being limited by external equipment capabilities.
Solution Approach 2:
The test functionality is merged with the existing I/O interface circuitry of the memory device. The same I/O buffer and signal paths used for normal memory operations are utilized for testing, combining the test function with the operational function to avoid adding separate dedicated test equipment.
2Reliability
If external test equipment is used for high-speed IO testing, then testing can be performed, but test costs soar due to specialized test arrangements
Solution Approach 1:
By enabling the memory device to perform self-testing, the patent eliminates the need for expensive external test equipment and specialized test arrangements. The built-in self-test circuitry uses the device's own resources to generate test patterns and verify results, making testing accessible without high-cost external equipment while maintaining reliable test coverage.
3Productivity
If memory operating frequency is increased, then data rate improves, but existing test equipment becomes ineffective
Solution Approach 1:
The memory device generates its own test clock signals and test patterns internally using its full operating frequency. This allows the device to test itself at any speed it can operate, eliminating the constraint where external test equipment must run faster than the device under test. The self-testing capability adapts automatically to the device's operating speed.
4Speed
If built-in self-test circuitry is implemented, then full-speed IO testing can be performed with low-cost equipment, but circuit size increases
Solution Approach 1:
The self-test circuitry is merged with the existing I/O interface structures. The test pattern generator uses the same data paths, the I/O buffer serves both normal operations and testing, and the register files are shared between operational and test modes. This integration minimizes the additional circuit area required for self-testing capabilities.
Solution Approach 2:
Existing I/O interface components are designed to serve multiple functions: the I/O buffer handles both data transfer during normal operations and data capture during testing; the register files store both operational data and test patterns/results; the clock generator provides clocks for both normal operation and test sequence generation. This multi-functionality reduces the need for dedicated test circuitry.
Data Source
AI summary
A memory interface circuitry includes a clock generator to convert the first clock signal into a second clock signal, a state machine to generate a test signal according to the second clock signal, a data pattern generator to generate a plurality of pre-defined data, a read register to sequentially output the plurality of pre-defined data, an I/O interface to capture a plurality of data from the plurality of pre-defined data according to a write strobe signal, a write register to receive and store the plurality of data from the I/O interface, and a comparator to compare the plurality of pre-defined data with the plurality of data to generate a test result. The test result is configured to verify an operation of the I/O interface.