RF/microwave test systems are each associated with specific circumstances, requirements, and challenges. Three universal factors come into play when defining any test system: performance, speed, and repeatability. Achieving the test system’s required level of measurement integrity involves making tradeoffs between the three factors mentioned. In the application note “6 Hints for Enhancing Measurement Integrity in RF/Microwave Test Systems,” Keysight Technologies discusses these tradeoffs and offers suggestions on how to address common problems.
The first hint that is presented is regarding the prioritization of performance, speed, and repeatability. The application note states that one or two of these will be the dominant factor that drives test requirements and equipment choices in most scenarios. Three tables are presented to show how each of the three factors mentioned affects the others.
Next, the importance of reviewing the nature and behavior of the device-under-test (DUT) is discussed. A typical automated test system performs the tasks of sourcing, measuring, and switching. Deciding which test instruments and cables to use depends on the electrical and mechanical attributes of the DUT. The application note emphasizes the need to avoid mismatches at connections, among other recommendations. Another point mentioned is the number and type of connectors for signals and power, as this has an impact on factors like the required size of switch matrices used in a test system and the complexity of system cabling.
Understanding, characterizing, and correcting RF signal paths are discussed next. The application note suggests that the calibration plane be as close as possible to the DUT. The next hint is about being aware of everything that is connected to an instrument, as everything between the instrument and the DUT can affect instrument performance and measurement repeatability. Three factors to take note of here are cables, switches, and signal conditioners.
The next topic concerns examining the operational attributes of switches. The operational attributes mentioned are device longevity, power requirements, and fail-safe operation. Lastly, the application note offers suggestions to accelerate measurement setup and execution time.
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