Agilent Technologies Agilent 4396B - Manual (Page 92)

Measuring Phase Response
A two input ratio measurement can also provide information about
the phase shift of a network. The analyzer can translate this
information into a related parameter , group delay .
With the same connection, instrument settings , and calibration used
in the previous example (see \Measurement Setup " in \Measuring
Transmission Characteristics of a Filter"), make the following changes:
1. Press 4 Chan 1 5 4 Sw eep 5
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
COUPLED CH on OFF to
NNNNNNNNNNNNNNNNNNNN
ON off to couple
sweep parameters of channel 2 to channel 1.
2. Press 4 Chan 2 5 4 F ormat 5
NNNNNNNNNNNNNNNNN
PHASE to display the phase response on
channel 2.
If the trace needs to be rescaled, press 4 Scale Ref 5 and
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
AUTO SCALE .
Figure 5-5 shows the phase response of the bandpass lter . Notice the
linear phase shift through the passband and the rapid
uctuations that
occur outside this region. The random phase of the broadband noise
oor causes the spurious out-of-band response .
This format displays phase over the range of 0180 to +180 degrees .
As phase increases beyond these values , a sharp 360 degree transition
occurs in the display as the trace \wraps" between +180 and 0180
degrees . This wrap causes the characteristic \sawtooth" display
usually seen on devices with linearly increasing (or decreasing) phase
responses .
Figure 5-5. Amplitude and Phase Response of a Dielectric Filter
5-6 Network Measurement Examples