HP 5989-3245EN free download

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Agilent Calibrating Standards for In-Fixture Device Characterization White Paper In many products such as PCS and cellular phones, the continuing miniaturization of components and subsystems Standards (SOLT) has all but eliminated the use of coaxial connectors as an internal interconnection method. In these products, a bandpass filter may be only a few centimeters long, and is mounted directly to the PC board, without connectors. DUT Measurement This presents a problem when using a vector network plane analyzer to evaluate the characteristics of a component, since there is no longer a well-characterized interface (the connector of the device under test) to which the analyzer can connect. Figure 1(a). A bandpass filter test fixture The answer is the test fixture, which is a good solution as long as it is well constructed, its characteristics are known, and its effects can be removed from the measurement results. The fixture must be calibrated, usually by means of the short-open-load-through (SOLT) calibration technique. Calibration of a fixture used to evaluate bandpass filters for mobile phones provides a good example of the details that must be considered and the process itself. The accuracy of in-fixture network measurements is directly related to the process used to calibrate the fixture. Figure 1a shows an example fixture for testing a bandpass filter. The fixture's SMA connectors are the interface to the network analyzer, and "pogo" type connectors connect to the filter under test. Its characteristics in the time domain with the through standard in place are shown in Figure 1b. Transitions in the fixture are readily identifiable -- and markers 1 and 4 show the transition at the SMA input and output connectors respectively, and markers 2 and 3 show the transition of the input Figure 1(b). Characteristics in the time domain with the through standard and output "pogo" connectors. Between markers 2 and 3 in place of the filter shown in Figure 1(a) is the reflection coefficient of the through standard, which can be used to calculate the transmission line impedance. 2 In the time domain, a network analyzer's gating function In-fixture Standards can be used to remove all data from the measurement except that obtained from the fixture. The match of the A set of in-fixture standards consists of a short, open, fixture may then be analyzed in the frequency domain load, and through, and is the same size as the DUT with gating on (Figure 2a). In this case, the gate starts