Datasheet

AD8331/AD8332/AD8334
Rev. G | Page 20 of 56
TEST CIRCUITS
MEASUREMENT CONSIDERATIONS
Figure 55 through Figure 68 show typical measurement
configurations and proper interface values for measurements
with 50 Ω conditions.
Short-circuit input noise measurements are made as shown in
Figure 62. The input-referred noise level is determined by
dividing the output noise by the numerical gain between Point A
and Point B and accounting for the noise floor of the spectrum
analyzer. The gain should be measured at each frequency of
interest and with low signal levels because a 50 Ω load is driven
directly. The generator is removed when noise measurements
are made.
0
3199-055
LMD
18nF
22pF
FB*
120nH
*
FERRITE BEAD
INOUT
0.1µF
DUT
NETWORK ANALYZE
R
0.1µF
28
237
28
1:1
5050
270
INH
237
0.1µF
0.1µF
Figure 55. Test Circuit—Gain and Bandwidth Measurements
10k
10k
03199-056
LMD
18nF
22pF
FB*
120nH
*FERRITE BEAD
INOUT
0.1µF
VGN
DUT
NETWORK ANALYZER
0.1µF
28
237
28
1:1
5050
INH
237
0.1µF
0.1µF
Figure 56. Test Circuit—Frequency Response for Various Matched Source Impedances
03199-057
LMD
22pF
FB*
120nH
*FERRITE BEAD
INOUT
0.1µF
VGN
DUT
NETWORK ANALYZER
0.1µF
28
237
28
1:1
5050
INH
237
0.1µF
0.1µF
Figure 57. Test Circuit—Frequency Response for Unterminated LNA, R
S
= 50 Ω