
Figure
EXBLK12
here.
Figure
12-7.
External
Source
Mode
Tuned
Receiv
er
Mode
In
tuned
receiv
er
mo
de,
the
analyzer
is
a
syn
thesized,
sw
ept,
narrow-band
receiv
er
only
.
The
external
signal
source
m
ust
b e
syn
thesized
and
reference-lo c
k
ed
to
the
analyzer.
T
o
ac
hiev
e
this,
the
analyzer's
source
and
phase
lo
c
k
circuits
are
completely
un
used.
See
Figure
12-8 .
The
fractional-N
syn
thesizer
is
tuned
so
that
one
of
its
harmonics
(1st
LO)
do
wn-con
v
erts
the
RF
input
to
the
samplers.
(In
con
trast
to
external
source
mo
de,
the
analyzer
do es
not
phase
lo
c
k
at
all.
Ho
w
ev
er,
the
1st
LO
is
syn
thesized.)
The
analyzer
can
function
as
a
sw
ept
tuned
receiv
er,
similar
to
a
sp ectrum
analyzer,
but
the
samplers
create
spurious
signals
at
certain
frequencies,
whic
h
limit
the
accuracy
of
suc
h
measuremen
ts.
Figure
TRBLK12
here.
Figure
12-8.
Tuned
Receiv
er
Mode
DRAFT
3/21/106
15:14
Theory
of
Operation
12-17
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