Test Apparatus Masking Data Acquisition During Clock Signal Interruptions
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Solution Overview
Problem
Devices using a source-synchronous interface intermittently stop outputting data and clock signals, requiring test apparatuses to pause data acquisition during these periods, leading to inefficiencies in testing.
Innovation Solution
A test apparatus with a masking section that synchronizes data acquisition with the clock signal, allowing for continuous testing by masking data acquisition during clock signal interruptions and using a sampling clock aligned with an internal reference clock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the test apparatus continuously samples data using the clock signal from the device under test, then the measurement precision is improved, but the reliability deteriorates because data is acquired during periods when the device under test is not outputting valid signals
Solution Approach 1:
The test apparatus preliminarily determines the output state of the device under test before acquiring data. The determination section checks whether the device under test is in an output state before the data acquiring section samples data, ensuring that only valid data is acquired and preventing erroneous sampling during idle periods
Solution Approach 2:
The test apparatus uses feedback from the determination section to control the data acquiring section. When the determination section detects that the device under test is not in an output state, it provides feedback to stop or mask data acquisition, thereby preventing invalid data from being sampled and ensuring reliable test results
2Reliability
If the test apparatus stops data acquisition when the device under test stops outputting signals, then the reliability is improved, but the productivity deteriorates due to interruptions in the testing process
Solution Approach 1:
By preliminarily determining the output state before data acquisition, the system avoids stopping and restarting the testing process. The determination section continuously monitors the output state, allowing the data acquiring section to smoothly acquire only valid data without interruption-induced overhead
Solution Approach 2:
The invention extracts only the valid data portions from the continuous signal stream by using the determination section to identify when the device under test is in an output state. This allows the test apparatus to process only meaningful data while maintaining continuous operation, thereby improving productivity without sacrificing reliability
3Productivity
If the test apparatus acquires data during all clock signal periods, then the productivity is improved, but the measurement precision deteriorates because data is acquired during periods when no valid data is output
Solution Approach 1:
The test apparatus extracts only the valid data portions by using the determination section to identify when the device under test is in an output state. This selective extraction maintains high productivity by continuously processing signals while ensuring measurement precision by acquiring only valid data
Solution Approach 2:
The determination section performs preliminary identification of valid output periods before data acquisition occurs. This preliminary action enables the data acquiring section to efficiently target only productive sampling opportunities, maintaining high throughput without compromising accuracy
Data Source
AI summary
Provided is a test apparatus that tests a device under test outputting a data signal and a clock signal indicating a timing at which the data signal is to be sampled, the test apparatus comprising a data acquiring section that acquires the data signal output by the device under test, at a timing corresponding to the clock signal output by the device under test; a masking section that masks the acquisition of data by the data acquiring section, while the device under test is not outputting the clock signal; and a judging section that judges pass/fail of the device under test based on a result of a comparison between the data signal acquired by the data acquiring section and an expected value.