AD8351
CHARACTERIZATION SETUP
The test circuit used for 150 Ω and 1 kΩ load testing is shown
in Figure 47. The evaluation board uses balun transformers to
simplify interfacing to single-ended test equipment. Balun effects
must be removed from the measurements to accurately charac-
terize the performance of the device at frequencies exceeding
1 GHz.
Data Sheet
The output L-pad matching networks provide a broadband
impedance match with minimum insertion loss. The input lines
are terminated with 50 Ω resistors for input impedance matching.
The power loss associated with these networks must be accounted
for when attempting to measure the gain of the device. The
required resistor values and the appropriate insertion loss and
correction factors used to assess the voltage gain are shown in
Table 5.
Table 5. Load Conditions Specified Differentially
Load Condition
R1 (Ω) R2 (Ω) Total Insertion Loss (dB)
150 Ω
43.2
86.6
5.8
1 kΩ
475
52.3
15.9
Conversion Factor 20 log (S21) to 20 log (AV)
7.6 dB
25.9 dB
RS
50Ω
BALANCED
SOURCE
RS
50Ω
RT
50Ω
50Ω CABLE
0.1nF
100nF R1
50Ω CABLE
RT
50Ω
AD8351 RLOAD
0.1nF DUT
100nF R1
50Ω CABLE
R2
50Ω CABLE
R2
50Ω
50Ω TEST
EQUIPMENT
50Ω
Figure 47. Test Circuit
Rev. D | Page 16 of 19