HP 8753D - Measuring Gain Compression

Measuring Gain
Compression
Gain
compression
occurs
when
the input
power of
an amplier
is increased
to a
level that
reduces
the
gain
of
the
amplier
and causes
a nonlinear
increase in
output power
.The
point at
which
the
gain
is
reduced
by
1dB
is called
the 1
dB compression
point. The
gain compression
will
vary
with
frequency
,
so
it is
necessary to
nd the
worst case
point of
gain compression
in
the
frequency
band.
Once
that
point
is
identied,
you
can perform
a power
sweep of
that
CW
frequency
to
measure
the
input
power
at
which
the
1dB
compression occurs
and the
absolute
power
out
(in
dBm)
at
compression.
The
following
steps
provide
detailed
instruction on
how to
apply various
features
of
the
analyzer
to
accomplish
these
measurements.
Figure
2-41.
Diagram
of
Gain
Compression
1.
Set
up
the
stimulus
and
response
parameters for
your
amplier
under
test.
T
o
reduce
the
eect
of
noise
on
the
trace
,
press:
4
A
V
G
5
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
IF
BW
N
N
N
N
N
N
N
N
N
N
N
N
N
N
1000
4
2
1
5
2.
Perform
the desired
error correction
procedure
.
Refer
to
Chapter
5,
\Optimizing
Measurement
Results,"
for instructions
on how
to
make
a
measurement
correction.
3.
Hook
up
the
amplier
under
test.
4.
To
produce a
normalized
trace
that
represents
gain
compression,
perform
either
step
5
or
step
6.
(Step 5
uses
trace
math
and
step
6
uses
uncoupled
channels
and
the display
function
N
N
N
N
N
N
N
N
N
NN
N
N
N
N
N
N
N
N
N
N
NN
N
N
N
N
N
N
N
N
N
N
N
NN
N
N
N
N
N
N
N
N
D1/D2 to D2 ON
.)
5.
Press 4
DISPLAY
5
NNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNN
DATA ! MEMORY
NNNNNN
NNNNNNNNNNNNNNNNNNNN
DATA/MEM to produce a normalized trace
.
6. T
o produce a normalized trace
, perform the
following steps:
a.
Press 4
DISPLAY
5 and select
NNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNN
DUAL CHANNEL ON
to view both channels simultaneously
.
Making Measurements 2-45