Calibrating Device Interface Board Signal Paths
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Solution Overview
Problem
Automatic test equipment (ATE) lacks comprehensive calibration beyond the specified calibration plane, particularly for signal transmission paths between the calibration plane and the device under test (DUT) signal contacts, leading to unknown performance characteristics in this region.
Innovation Solution
A test system with a device interface board (DIB) that injects test signals and measures their transmitted versions to generate calibration factors, correcting for effects such as power, frequency, linearity, gain, and impedance changes along the signal transmission paths, which are stored in computer memory and used to correct signals passing through the DIB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed only at the specified calibration plane, then the calibration process is simple and fast, but the signal transmission accuracy beyond the calibration plane (to DUT signal contacts) is unknown and inaccurate
Solution Approach 1:
The calibration process is segmented into two distinct parts: (1) calibration at the calibration plane using standard procedures, and (2) separate measurement and characterization of the signal transmission paths between the calibration plane and DUT signal contacts. This segmentation allows each part to be optimized independently, achieving high accuracy without overly complicating the overall process.
Solution Approach 2:
The patent introduces an intermediary measurement system that characterizes the signal transmission paths. This intermediary layer captures the effects of the transmission paths (insertion loss, impedance, time delay) and uses this information to correct measurements, thereby extending accurate calibration beyond the original calibration plane without requiring direct recalibration at each point.
2Measurement precision
If comprehensive calibration of signal transmission paths is performed, then signal accuracy is improved, but the calibration time and resources increase
Solution Approach 1:
The signal transmission path characteristics (insertion loss, impedance, time delay) are measured and stored in advance during the calibration process. This preliminary characterization allows the system to apply pre-determined correction factors during actual testing, eliminating the need for repeated time-consuming measurements and enabling fast, accurate testing thereafter.
Solution Approach 2:
The patent creates a digital model (copy) of the signal transmission paths by measuring their characteristics and storing them in a data structure. This digital copy contains all the necessary information about the transmission paths and can be reused multiple times without additional physical measurements, significantly reducing calibration time for subsequent tests.
3Adaptability or versatility
If calibration factors are stored locally on the DIB, then re-calibration is unnecessary when reusing DIBs, but the system requires additional memory resources on the DIB
Solution Approach 1:
The calibration data (signal transmission path characteristics) is extracted from the measurement system and stored locally on the DIB itself in a data structure. This extraction allows the DIB to be self-contained and portable, carrying its own calibration information so it can be reused in different test systems without requiring re-calibration or external lookup tables.
Data Source
AI summary
An example test system includes a device interface board (DIB) having one or more signal transmission paths and an interface for connecting to one or more other components of the test system. Test circuitry is configured to inject test signals into the one or more signal transmission paths and to measure transmitted versions of the test signals at the interface to obtain measurement signals. One or more processing devices are configured to generate calibration factors based on differences between the injected test signals and the measurement signals, and to store the calibration factors in computer memory. The calibration factors are for correcting for effects on the test signals of the one or more signal transmission paths.