Agilent Technologies HP 83711A - Page 129

Ke
ys/Shifted
Functions
EXT DIODE
Figure
6-1.
External
Diode
Detector
Leveling
Setup
When
external
diode
detector
leveling
is
chosen,
power
is
sampled
at
the
external
sampling
device
(either
a
directional
coupler
or
power
splitter)
by
an
external
diode
detector
that
is
typically
operating
in
the
square
law
region.
When
the
diode
detector
is
operating
in
the square
law region,
it
will
provide
a
DC
voltage
that
is
proportional
to
the power
sampled at
the
input
to
the
detector
.
This
DC
voltage
is
fed
back
to
the synthesizer
via
the
ALC
IN
connector
.
The
synthesizer
then
adjusts
its
output
power
level to
maintain
a
constant
power
level
at
the
input
to
the
external
diode
detector.
Applications
External
leveling
can
be
used
when
your application
requires long
cables
that
will
cause
frequency-dependent
losses
.
It also
enables devices
,such
as
ampliers,
mixers,
etc. to
be
inserted
into
the
RF
signal
path
so
that
the
output of
the inserted
device is
controlled by
the
synthesizer
.
6-17