HP 8753D - Page 379

Frequency
Oset
Menu
If
you press
4
SYSTEM
5
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INSTRUMENT
MODE
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FREQ
OFFS MENU
,the
analyzer allows
phase-locked
operation
with
a
frequency oset
between the
internal source
and receiver
. This
feature is
used
in
swept
RF mixer
measurements and
has an
upper frequency
limit equal
to that
of the
analyzer
being
used.
This
feature
allows
you
to
set
the
RF source
to a
xed oset
frequency
above
or
below
the
receiver
(as
required
in a
mixer test,
using a
swept
RF/IF
and
xed
LO).
Then
you
can
input
a
signal
to
a
device over
one frequency
range and
view
its
response
over
a
dierent
frequency
range
.
The
maximum delay
between the
RF source
and the
R
input
is
0.3
microseconds
.
The
analyzer
will
show
a signal
that is
a composite
of the
desired
RF
signal,
image
response
,
and
spurious
signals
.
Y
ou can
use the
frequency oset
in
any
sweep
type
in
network
analyzer
mode
.
The
two
user-dened
variables in
this mode
are receiver
frequency
and
oset
frequency
(LO).
The
analyzer
automatically sets
the source
frequency
equal
to
IF
+
LO
or
IF
0
LO
.
Mixer
measurements
and
frequency
oset
mode
applications
are explained
in
application
note
8753-2,
\RF
Component
Measurements
Mixer
Measurements
using
the
HP
8753B
Network
Analyzer
,"
HP
part
number
5956-4362.
This
application
note
was
written for
the HP
8753B but
also
applies
to
the
HP
8753D
.
Also
see
product
note 8753-2A,
HP part
number 5952-2771.
Primary
Applications
Frequency
oset
mode
is
useful
for
the following
types
of
measurements
on
frequency-
translating
device:
conversion
loss
conversion
compression
amplitude and
phase tracking
Typical T
est Setup
Figure 6-59
shows a
typical test
setup
using
frequency
oset
mode
.
Instructions
are
provided
in Chapter
3, \Making
Mixer Measurements
."
The
attenuators
shown
reduce
mismatch
uncertainties
.
The
low
pass
lter
keeps
unwanted
mixing
products
out
of
the
sampler
.
6-112 Application and Operation Concepts