HP 70427A User Manual page 103

Downconverter Operation
Phase Noise Measurement <26.5 GHz User Control
•
1.0 ppm/V (600 MHz PLL bandwidth must be greater than
the HP 3048A PLL bandwidth)
•
20 ppm/V
Noise performance depends on tuning sensitivity so it may be necessary to
trade off noise performance for tuning range. Refer to the specification table
in chapter 9 for noise performance for each tuning sensitivity.
Tuning the DUT:
Refer to the Signal Source Applications chapter of the HP 3048A manual
for information on tuning the DUT.
Step 4 - Select the downconverter tuning sensitivity
Do this only if the downconverter is being used.
1. Press the softkey.
Ref Chain
2. Press the
Tune Sens
3. Press the or the
1.0 ppm/V
Step 5 - Change the 600 MHz PLL bandwidth (if needed)
The only reason to use anything other than the default bandwidth is if the
downconverter is being tuned using the ppm/V tuning sensitivity, and the HP
3048A system PLL bandwidth is greater than 10 kHz. If the downconverter
is being tuned, its phase-lock-loop bandwidth must be wider than the HP
3048A system bandwidth. If it isn't, the system software can't accurately
compensate for loop suppression.
1. Press the softkey.
Ref Chain
2. Press the
600 MHz PLL BW
3. Press the appropriate bandwidth softkey.
Step 6 - Define the measurement
Follow the instructions in the HP 3048A manual together with the
information below:
1. Specify Measurement Type and Frequency Range
•
Measurement type: Phase Noise using a Phase Lock Loop
2. Enter Source and Interface Parameters
•
Carrier Frequency: Downconverter's input frequency
•
Detector/Disc. Input Frequency: Downconverter's IF frequency
•
VCO Tuning Constant: This depends on which instrument will be tuned:
HP 70427A: ...................................carrier frequency
3-4 HP 70427A/HP 70428A User's Guide
softkey.
softkey.
20 ppm/V
softkey.
×
Tuning Sensitivity