AD8351

Data Sheet

Rev. D | Page 16 of 19

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.

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)

Conversion Factor 20 log (S21) to 20 log (AV)

150 Ω

43.2

86.6

5.8

7.6 dB

1 kΩ

475

52.3

15.9

25.9 dB

Figure 47. Test Circuit

0.1nF

0.1nF

100nF

100nF

RLOAD

AD8351

DUT

R1

R1

R2

R2

50Ω

50Ω

50Ω TEST

EQUIPMENT

BALANCED

SOURCE

RS

50Ω

RT

50Ω

RT

50Ω

RS

50Ω

50Ω CABLE

50Ω CABLE

50Ω CABLE

50Ω CABLE