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UNCORRECTED POWER
CORRECTED POWER OUTPUT POWER
Agilent PN 8510-16
Controlling Test Port Output
Power Flatness
Product Note
Agilent 8510C Network Analyzer
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Power flatness correction is useful for characteriz- Introduction ing active devices by allowing measurements of Designers and manufacturers of active devices absolute power, gain versus input power, and often need to control the power level at the test 1 swept-frequency gain compression. Swept-power port of their power-sensitive devices, but find dif- gain compression measurements are possible in ficulty in overcoming insertion losses. The insertion the power domain with the flatness correction
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The Agilent 8511B frequency converter test System Configuration set may be used with the test port power flatness- The basic 8510C measurement system configura- correction feature. The range of the test port tion needed for test port flatness correction is power is determined by the available power of shown in Figure 1. A single channel power meter the 8360 source and the insertion loss of the com- such as the Agilent 437B, E4418A, or E4418B is ponents added to the measurement system. required
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When the flatness correction is enabled in an Flatness-Correction Operation 8510C measurement system the analyzer’s Power The basic setup procedure to obtain flat test port Source 1 softkey controls the test port power level. output power is illustrated in Table 1. To simplify The source and test set used will determine the the execution of the procedure, the front panel available test port power range. hardkeys are enclosed in [brackets]. The softkeys are enclosed in {braces}. Table 2 provides
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Table 1. Flatness-correction calibration procedure 8510C Keystrokes Description Set up the power meter (see Table 2) For proper operation, the E4418B must be set up before initiating the flatness-correction routine. See Table 2 for specific instructions. Verify the power meter's address on the 8510 system [LOCAL] When shipped from the factory, the address of the power meter is 13. If this conflicts with another instrument on the system bus, {POWERMETER} change the address of the conflicting in
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Table 2. Agilent E4418B power meter setup E4418B Keystrokes Description Preset and zero the power meter [PRESET/LOCAL] Return the power meter to a known state. {CONFIRM} [ZERO/CAL] {ZERO} Set up the 437B emulation on the power meter [SYSTEM/INPUTS] The 437B command set must be activated in order to perform the power flatness calibration. Power meters that can be used in {REMOTE INTERFACE} place of the E4418B are the E4418A and 437B. The E4419B dual channel power meter does not have the 437B
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Operational Considerations Calibration time The user may choose to speed up the calibration process by reducing the number of trace points on the analyzer. Table 5 provides some typical calibration times for flatness correction over the full frequency span of the source for different source/test set combinations. Calibration times may be slightly reduced by increasing the stepped measurement speed with the quick step feature on the Agilent 8510C. Table 5. Typical calibration times (in minutes) v
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Verifying a flatness-correction calibration When to recalibrate To verify the flatness-correction calibration, the The flatness-correction calibration does not need power sensor should be reconnected to the test to be repeated unless: (1) the user wants to cali- port to measure the test port power at individual brate over a wider frequency range, (2) the meas- frequencies. Since the measurement system is urement path between the source and the test calibrated in 50W, inaccuracies will occur when
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Using test port 1 calibrations on test port 2 Flatness corrections in fixture or wafer-probing In most cases, port 1 will be the input port of the environments DUT. When port 2 must be used as the input port Test port flatness correction may be applied to the device, the user may choose to use a port 1 with any other power function. Power slope may flatness-correction calibration on port 2 since the be used to compensate for the path loss in non- 1 port 1 and port 2 signal paths are symmetric
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Practical Application Examples Absolute output power measurements with flatness correction One benefit of the flatness-correction capability is the ability to measure the absolute output power of active devices. Since the input power level to the DUT is kept constant, the magnitude offset feature of the Agilent 8510 can be used to display absolute output power across the entire frequency span of the device. Table 6 shows the procedure for absolute output power versus frequency measure- ments wi
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Amplifier measurement example output power, and gain compression measurements Step-by-step instructions for setting up and apply- procedures are covered. For more information on ing flatness corrections for the measurement of measuring amplifiers, refer to Agilent product note an amplifier are shown in Table 7. Gain, absolute 8510-18, literature number 5963-2352E. Table 7. Absolute output power and 1 dB compression measurements of an amplifier 8510C Keystrokes Description Perform the flatness-co
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