Power level is the power of the source at the test ports.
See other 'Setup Measurements' topics
The test port output power is specified over frequency.
See the Power Range specifications for your analyzer.
How to make Power settingsUse one of the following methods to set port power. |
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Using Hardkey/SoftTab/Softkey |
Using a mouse |
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This dialog provides basic control of source power for a specific port. See Power and Attenuators dialog box. Power On (All Channels) Check to enable source power for all channels. Only turns power ON if channel power setting is ON or Auto. Port 'n' Active source port for which power is being set. Port Power Sets the power level for the specified port. To accurately set the power level at any point after the test port, perform a Source Power Calibration. Power SweepStart / Stop Power Set the start and stop power values of a power sweep.
Power SlopeHelps compensate for cable and test fixture power losses at increased frequency. Slope Select to set the power slope. Clear to set power slope OFF. Learn more about power slope. |
How to make Power settingsUse one of the following methods to set port power. |
Using Hardkey/SoftTab/Softkey |
Detailed settings for Power and Attenuators:
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Defines and controls the source power and attenuation for the active channel. Note: External sources can be controlled from this dialog. Learn more. Power On (All Channels) Check to enable source power for all channels (same function as RF Power). Only turns power ON if channel power setting is ON or Auto.
Name Lists the analyzer test ports.
Port Power Sets the power level at the output of the source.
Start / Stop Power Available ONLY when sweep type is set to Power Sweep. Set the start and stop power values of a power sweep. Learn how to set Power Sweep.
Auto Range Check to allow the analyzer to select the optimum attenuation value to achieve the specified test port power. Clear to manually set the attenuation for each port. Type or select the attenuation value in the adjacent Attenuator Control box. When using manual attenuation (Auto Range cleared), Port Power can be set within a 60 dB range. For example:
Important Note: The available power range can also be adjusted AUTOMATICALLY by a Source Power Calibration, Guided Power Cal, or Power Compensation. If you are NOT seeing the range that you expect, or the correct power level at your DUT, view the Power Offset column in the Power Limits and Offsets dialog. Source Attenuator When Port Powers are Uncoupled, manual attenuator control allows you to set a wide range of power levels by setting the attenuation. See Setting Independent Port Power. Also use manual attenuation control when a measurement requires a very good impedance match with the source, such as with oscillators or conditionally unstable amplifiers. Choose an attenuation level of 10 dB or more to ensure the best source match.
Default Source Attenuation Based on Measurement ClassThe table below lists the default source attenuation values (dB) for each port, based on the selected measurement class. These are the initial source attenuation values that appear when you open the Power and Attenuators dialog box.
Leveling Mode (ALC Hardware Softkey)- Refer to the following diagram:
Channel Power SlopeHelps compensate for cable and test fixture power losses at increased frequency. With power slope enabled, the port output power increases (enter positive value) or decreases (enter negative value) as the sweep frequency increases. Slope Select to set the power slope. Clear to set power slope OFF. Power slope is computed and applied from 0 GHz – not from the measurement start frequency. For example, with the following measurement settings:
The power into the DUT from 10 GHz to 20 GHz is 10 dBm sloping to 20 dBm Offset and Limits Launches the Power Offset and Limits dialog. Receiver Leveling Launches the Receiver Leveling dialog. Receiver Attenuator Launches the Receiver Attenuator dialog. Path Configurator Launches the Path Configurator dialog. When the power level that is required at a test port is higher than can be supplied, a Source Unleveled error message appears on the screen and the letters LVL appear on the status bar. To perform a power sweep, the range of power is usually limited to the range of the Automatic Leveling Control (ALC) loop. (The PNA-X allows a very wide power range using Open Loop). Specifications guarantee the ALC power range over which power can be supplied without an unleveled indication. However, the actual achievable power range on your analyzer is probably greater than the specified range. How to calculate the specified achievable power rangeFrom the specifications for a frequency span from 15 GHz to 20 GHz:
For this frequency range the specified power range is calculated as:
When using Source Attenuators:
To resolve an unleveled condition, change either the Test Port Power or Attenuator setting. Important Note: The available power range can also be adjusted AUTOMATICALLY by a Source Power Calibration, Guided Power Cal, or Power Compensation. If you are NOT seeing the range that you expect, or the correct power level at your DUT, view the Power Offset column in the Power Limits and Offsets dialog. Setting Independent Port Power You can uncouple port power and specify different power levels at each test port. There are a few things to consider when setting independent port powers.
Setting Port Power On/Off for the Second source and Multi Module/Unit configurationWhen the unit has the second source capability or multi module/unit configuration in PXI/USB VNA, Source power ALWAYS ON can be applied for each source group. The following dialog shows an example of three module configuration of six, four and two port PXI VNAs. In this case, there are three independent source group, port 1to 6, 7 to 10 and 11 to 12. You can set one port in each group at ON state. The attenuator has different positions, allowing a wide range of power levels. The number of power ranges available is determined by the source attenuation installed in your VNA. See VNA Options to see the availability and range of source attenuation on your VNA.
Note: Error correction is fully accurate only for the power level at which a measurement calibration was performed. However, when changing power within the same attenuator range at which the measurement calibration was performed, ratioed measurements can be made with nearly full accuracy (non-ratioed measurements with less accuracy).
Power ON and OFF during Save / Recall, User Preset, and Preset To protect your DUT from being inadvertently powered ON, the following RF Power ON/OFF settings occur: Instrument State Save/RecallIf power is OFF when an instrument state is saved, then power will always be OFF after the instrument state is recalled. If power is ON when an instrument state is saved, and the current power setting is OFF, then power will be OFF after the instrument state is recalled. User PresetIf power is OFF when a User Preset is saved, then power will always be OFF after a User Preset. If power is ON when a User Preset is saved, and the current power setting is OFF, then power will be OFF after a User Preset. PresetInstrument Preset sets power ON by default. This can be changed with a Preference setting so that, if the current power setting is OFF, then power will be OFF after Preset. Power ON and OFF during Sweep and Retrace The frequency range of the VNA covers several internal frequency bands. The higher the frequency range of the VNA, the larger the number of bands. For example, a 9 GHz VNA has 6 frequency bands, a 50 GHz VNA has 25 frequency bands. See the frequency band crossings. Power to the DUT is turned OFF during band changes to avoid causing power spikes to the DUT. Retrace occurs when the source gets to the end of your selected frequency span and moves back to the start frequency. Power to the DUT is again turned OFF when retracing across frequency bands. The following power ON/OFF states occur for various stimulus settings:
Caution: Avoid expensive repairs to your analyzer. Read Electrostatic Discharge Protection.
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