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134 Chapter 4
Optimizing Performance
Adjusting Reference Oscillator Bandwidth (Option UNR/UNX)
Recalling and Applying a User Flatness Correction Array
Before performing the steps in this section, complete the section “Creating a User Flatness Correction
Array with a mm-Wave Source Module” on page 128.
1. Press
Preset.
2. Press
Amplitude > More (1 of 2) > User Flatness > Configure Cal Array > More (1 of 2) > Preset List > Confirm Preset.
3. Press
More (2 of 2) > Load/Store.
4. Ensure that the file FLATCAL2 is highlighted.
5. Press
Load From Selected File > Confirm Load From File.
This populates the user flatness correction array with the data contained in the file FLATCAL2.
The user flatness correction array title displays User Flatness: FLATCAL2.
6. Press
Return > Flatness Off On.
This activates flatness correction using the data contained in the file FLATCAL2.
Adjusting Reference Oscillator Bandwidth (Option UNR/UNX)
The reference oscillator bandwidth (sometimes referred to as loop bandwidth) in signal generators
with Option UNR/UNX (improved close-in phase noise < 1 kHz) is adjustable in fixed steps for either
an internal or external 10 MHz frequency reference. The reference oscillator bandwidth can be set to
25, 55, 125, 300, or 650 Hz; models without Option UNR/UNX have a fixed reference oscillator
bandwidth of about 15 Hz.
At frequency offsets below approximately 1 kHz, the stability and phase noise are determined by the
internal or external frequency reference. At frequency offsets above 1 kHz, stability and phase noise
are determined by the synthesizer hardware.
To optimize the overall phase noise performance of the signal generator for your particular
application, make this adjustment depending on your confidence in the stability and phase noise of
the external or internal reference versus the synthesizer hardware for various frequency offsets from
the carrier.
To Select the Reference Oscillator Bandwidth
When using the internal timebase reference:
1. Press
Utility > Instrument Adjustments > Reference Oscillator Adjustment > Internal Ref Bandwidth.
2. Select the desired bandwidth.
When using an external timebase reference:
1. Press
Utility > Instrument Adjustments > Reference Oscillator Adjustment > External Ref Bandwidth.
2. Select the desired bandwidth.