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Phase or Group Delay Measurements
For information on group delay principles, refer to “Group Delay Principles” in Chapter 6.
The accuracy of this measurement depends on the quality of the mixer that is being used for
calibration and how well this mixer has been characterized. The following measurement must
be performed with a broadband calibration mixer that has a known group delay. The following
table lists the specifications of two mixers that may be used for calibration:
1.
2.
3.
4.
Model
Nnmber
ANZAC
MCD-123
USefIll
Group
Freqaency
Bange
DeLay
.03
to 3
Gllz
.5
ns
Mini~ircui~
ZFM-4
dc to 1250 MHz
.6
ns
Set the LO source to the desired CW frequency and power level. For this example the LO
source is set to the following values:
CW frequency = 1000 MHz
power = 13
dRm
Initialize the analyzer by pressing
Q%+.
From the front panel of the HP 8753E, set the desired receiver frequency and source
output power by pressing:
Connect the instruments as shown in Figure 3-17, placing a broadband “calibration” mixer
(ZFM-4)
between PORT 1 and PORT 2.
Caution
To prevent connector damage, use an adapter (HP part number 1250-1462) as a
connector saver for R CHANNEL IN.
3-24
Making Mixer Measurements