LeCroy SPARQ Pass/Fail Testing Capability
LeCroy SPARQ users can perform pass/fail testing on S-parameters, time domain views or on math and zoom traces. Up to 8 pass/fail conditions can be configured to determine an overall pass/fail result. Conditions can be either limit tests using waveform measurements, or mask tests to determine if a trace remains in an allowed region or outside of a disallowed region. Users can configure actions to occur on a passing or failing result, and can read back the results via remote control. This application note shows pass/fail testing performed on an impedance profile of a test board with coupled differential lines that should maintain an impedance of ~68 ohms. If the impedance within the coupled region stays with 65-70 ohms, the test passes; otherwise the test fails.
Configuring Pass/Fail Testing
Users configure the conditions via the Pass/Fail dialog, which is an item in the Analysis menu. The dialog includes tabs for each of the 8 conditions (“Qx”) that may be enabled for use (shown in figure 1). For each Qx being setup, the user can select the whether to compare to a parametric measurement result or to perform mask testing, and configure the type of comparison to make. The Pass/Fail tab (not shown) includes a master enable checkbox to turn testing on or off, and shows a summary of the configured conditions. The Actions tab includes allows users to configure the overall logic to use (i.e. whether to consider “true” as passing or failing), and what actions to take in case of a passing or failing result.
n Figure 1 we have configured Q1 to test against the value of the measurement configured in measurement slot P1. Q2 is configured to test on the value of measurement P2. P1 is configured to measure the maximum value of trace S1 (shown in figure 2), and P2 is configured for the minimum of S1. In figure 1, the limit condition for Q1 is shown; Q1 = All P1<=70. Condition Q2 = All P2 >=65. (Note that some measurements – especially “horizontal” measurements – are “multi-valued”, such that you can test against “all” or “any” of the measured values. Since the Max and Min measurements are single-valued, the choice of “all” or “any” does not apply.)
Measurement Setup
The Maximum and Minimum measurements have been configured in measurement slots P1 and P2 via the SPARQ’s parametric measurement feature (via the Measure menu.) For both P1 and P2, the measurement is being performed within grids 2 through 6 by configuration of the measure gates, as shown in figure 2. The result of the measurement on a sample DUT is also shown in figure 2.
The trace shown (trace identifier S1) is the impedance profile looking into port 1. S1 was configured to use the S11 Sparameter, and to display the Z result type. When configuring to show timedomain responses, the user can configure a risetime to use; for this example, 10ps was configured. The trace has also been zoomed to setting that is convenient for viewing.
Pass/Fail Test Results
For this DUT, the Q1 and Q2 tests both pass, yielding an overall passing result for the impedance test for port 1. The results for each individual condition are shown in the table: Q1: True, Q2: True. The overall result is shown as well: (Q1&Q2) = True. The pass/fail logic has been set to pass if all conditions are True; users can change the logic used in the Pass/Fail Actions dialog. This test is easily extended to test multiple ports at one time by setting up additional traces, such as S2 = Z(S22), and configuring Max and Min measurements in slots P3 and P4. The results of each individual condition can be viewed or readout via remote control, as well as the overall result.
Remote Control Readout
The SPARQ application can be controlled and monitored via almost any programming environment. Figure 3 shows the LabVIEW VI to read back the overall pass/fail result. The results of each individual condition can be read out as well.
Going Beyond Limit Testing
The example above shows pass/fail testing using limit tests on waveform measurements. Users can configure conditions to perform mask-testing as well. Figure 4 below shows the SPARQ performing pass/fail mask testing on two insertion loss plots (upper left and right grids), a peak-to-peak test on an impedance profile (lower left), and a test against the maximum value of a mode conversion result (lower right). Conditions Q2 and Q4 fail the tests, Q1 and Q3 pass. For more information on making masks and performing mask testing, see the application note on this topic.
