ina-12063 Avago Technologies, ina-12063 Datasheet - Page 18

• Manufacturer Part Number: ina-12063
• Description: 1.5 Ghz Low Noise Self-biased Transistor Amplifier - -packard
• Manufacturer: Avago Technologies

Actual, measured test results are
shown in Figures 24 through 28.
Output power for 1 dB of gain
compression (P
was measured as -4.6 dBm.
Figure 24. Measured Gain of Example
900 MHz LNA.
Figure 25. Measured Noise Figure of
Example 900 MHz LNA.
Figure 26. Measured Input and
Output Return Loss of Example
900ּ MHz LNA.
-10
-15
-20
-25
-30
-35
20
15
10
-5
5
0
4
3
2
1
0
800
800
0
800
Input
850
850
850
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (MHz)
1dB
900
900
900
) at 900 MHz
Output
950
950
950
1000
1000
1000
Figure 27. Measured Gain of Example
900 MHz LNA for Extended Frequency.
Figure 28. Measured Input and Output
Return Loss of Example 900 ּ MHz LNA
for Extended Frequency.
Results of this step:
A prototype circuit was built and
performance goals verified by
measurement. The following
900ּ MHz data was measured on
the example LNA:
NF = 1.9 dB
Gain = 14.7 dB
P
Input Return Loss = 9.6 dB
Output Return Loss = 20.4 dB
DC Power = 8 mW
-10
-15
-20
20
15
10
-5
-5
1dB
5
0
100
0
100
(output) = -4.6 dBm
(Input VSWR = 2.0 : 1)
(Output VSWR = 1.2 : 1)
(3 volts, 2.55 mA)
500
500
FREQUENCY (MHz)
FREQUENCY (MHz)
6-133
900
900
Input
1300
1300
Output
1700
1700
2100
2100
Hints and Troubleshooting
• Oscillation
Even though a design may be
unconditionally stable (K > 1 and
B1 > 0) over its full frequency
range, other possibilities exist
that may cause an amplifier
circuit to oscillate. One thing to
look for, is oscillation in bias
circuits. It is important to capaci-
tively bypass the connections to
active bias circuits to ensure
stable operation. In multistage
circuits, feedback through bias
lines can also lead to oscillation.
Components of insufficient
quality for the frequency range of
the amplifier can sometimes lead
to instability. Also, component
values that are chosen to be much
higher in value than is appropri-
ate for the application can
present a problem. In both of
these cases, the components may
have reactive parasitics that make
their impedances very different
than expected. Chip capacitors
may have excessive inductance,
or chip inductors can exhibit
resonances at unexpected
frequencies.
In systems with high gain cas-
cades, another possible feedback
path that could lead to oscillation
is radiation. Feedback via radia-
tion is most frequently encoun-
tered in situations where a large
cavity housing is used in combi-
nation with multiple gain stages.
One solution to minimizing
radiation feedback is to design
the housing so that it is well
below its equivalent waveguide
cutoff frequency. Another solu-
tion is to use shielding to parti-
tion the gain.