Features
• 24 dB Gain
• 6.5 dB Noise Figure
• Probe-Power Bias Connection
• Compact Size
Benchtop/general purpose use
Used alone on the bench, the Agilent Technologies
87405A can be added to any application in which
additional gain and low noise are required. The
compact and inexpensive 11899A probe power
supply is a suitable source of DC bias in remote
applications.
The Agilent 87405A preamplifier brings reliable
gain and low noise figure to measurement systems
to improve overall system performance and reduce
systematic errors. With its compact size and convenient probe-power bias connection, the 87405A
is ideal for use as the front end preamplifier for a
variety of Agilent instruments such as the 8590E
series of portable spectrum analyzers. The 87405A
is the recommended preamplifier for use with the
8594E Noise Figure Measurement Solution. The
rugged design along with its insertable configuration of connectors makes the 87405A ideal for
test port applications.
Agilent 87405A
Preamplifier 10 MHz to 3 GHz
Data Sheet
2
Improve noise figure measurements
Add a preamplifier to noise figure measurement
systems to significantly lower system noise figure.
The noise figure of the system is dominated by the
noise figure of the preamplifier.
F
new
= F pa + F
sys
- 1
G
pa
Where F and G are noise figure and preamplifier
gain, both in linear terms.
NF
sys
= 10 log (F
sys
) in dB
For systems having a single preamplifier, where
the gain of the preamplifier is greater than or
equal to the spectrum analyzer noise figure, the
system noise figure approximately equals the noise
figure of the preamplifier.
Increase sensitivity and speed
Adding preamplifiers to measurement systems can
improve sensitivity for measuring low-level signals.
Boost the sensitivity of your Agilent spectrum analyzer 15 to 25 dB by using the 87405A preamplifier.
Alternatively, better sensitivity can be traded for
measurement speed. Spurious tests often require
narrow resolution bandwidths to reduce the noise
floor of the analyzer, allowing low-level signal
detection. An analyzer with low noise figure allows
you to use a wider resolution bandwidth, yet
achieve the same sensitivity. Sweeptimes can
improve one hundred fold for each decade increase
in bandwidth. The 87405A preamplifier has gain
and noise figure characteristics that optimize
dynamic range and sensitivity.
Gain (dB)
28
27
26
25
24
23
22
21
0.01
0.5 1
1.5
2 2.5 3
Frequency (GHz)
Noise Figure (dB)
10
9
8
7
6
5
4
3
0.01
0.5 1
1.5
2 2.5 3
Frequency (GHz)
2
1
Output Power (dBm) @ 1 dB compression (dB)
12
11
10
9
8
7
6
5
0.01
0.5 1
1.5
2 2.5 3
Frequency (GHz)
4
3