Agilent Measurement Journal - Issue 5 - 2008 - (Page 69)

Repeatability on measurement uncertainty The repeatability of a switch has a direct effect on the measurement uncertainty of a test setup. Figure 8 shows an Agilent PNA network analyzer connected to a multi-port test set, which is used to test multiple devices. In this example, a total of three two-port devices can be tested simultaneously with any port. Because these errors are random rather than systematic, a root sum square (RSS) calculation is used to determine the total measurement uncertainty. Here, two scenarios are presented: Scenario 1. PNA repeatability 0.01 dB, EM Switch repeatability 0.03 dB Total measurement uncertainty 0.012 + 0.03 2 + 0.03 2 0.044 dB The repeatability of the EM switch has a signiﬁcant effect on the total measurement uncertainty of the system, in turn affecting the accuracy of all measurements. The wiping-action design of Agilent EM switches removes particle buildup to maintain a repeatability speciﬁcation of 0.03 dB. This is crucial for ensuring a lower cost of test. Conclusion Operating life and switching repeatability are important criteria that must be considered when selecting an EM switch. Operating life is highly dependent on the jumper-contact mechanism, contact resistance, materials and plating used in all key RF components. As a result, these factors must be carefully considered during the design phase, and steps should be taken to ensure that they do not adversely affect operating life and switching repeatability. Doing so delivers the lower cost of test that today’s high-volume component manufacturers demand. Scenario 2. PNA repeatability 0.01 dB, EM Switch repeatability 0.1 dB Total measurement uncertainty 0.012 + 0.1 2 + 0.1 2 0.142 dB PNA network analyzer Figure 8. PNA network analyzer with a multi-port test set

Table of Contents Feed for the Digital Edition of Agilent Measurement Journal - Issue 5 - 2008

Agilent Measurement Journal Issue 5 Finding a New Path when Assumptions Break Down Contents Testing MIPI D-PHY Protocols Oscilloscope Firmware Update DNA Replication Joining the LTE/SAE Trial Initiative Testing Proteins Praise for DC Power Analyzer Scripting Features for AMDS Testing Hybrid PCBA Systems Improving the Gene Expression System Workflow Turning a “Good Enough” Test Strategy into One That’s Reliable, Repeatable and Traceable Understanding the Effects of Limited-Bandwidth Channels on Digital Data Signals Introducing the 3GPP LTE Downlink Validating the 26 Validating the Physical and Protocol Layers in DDR Memory Interfaces Understanding Total Jitter Measurements of Low Probabilities Using Behavioral-Model Simulation to Accurately Predict First-Order PLL Performance Creating Synchronous High-Frequency Sampling across Multiple Digitizers Overcoming the Challenges of Testing FlexRay Networks Understanding Operating Life and Repeatability of Electromechanical Switches and their Effect on Total Cost of Ownership Implementing Micro and Nano LC/MS Techniques for High Sensitivity Lipidomics Analysis

Agilent Measurement Journal - Issue 5 - 2008

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