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Preliminary
3-8
RF3330
Rev A2 010820
3
Output
On the output, the losses due to the resistive matching
pad must also be calibrated out of the setup. Because
of the 1:1 transformer, the spectrum analyzer appears
as a 50
Ω resistor in parallel with this circuit (see Figure
2). Equation 4 illustrates the calculation necessary to
obtain the amount of loss due to this matching circuit.
The balun also has an additional 0.5dB to 1.0dB of
loss, which is added in to the overall output losses.
This was verified with a spectrum analyzer probe. The
offset used in the test setup is 32.5dB on the spectrum
analyzer.
Resistive Pad Loss=
20*log(25/ (470 +25+ 470))=-31.7dB
Eq. 4
3330410 Evaluation Board
1:1
Transformer
Frequency =
1MHz to
150 MHz
Spectrum Analyzer
Resistive
Match
Mini-Circuits
ZMSCJ-2-1
Divider
Frequency =
1MHz to
150 MHz
Frequency =
1MHz to
150 MHz
Signal Generator
RF3330
Figure 1. RF3330 Test Setup
R4
470
Ω
R3
51
Ω
50
Ω
R2
470
Ω
Figure 2. Equivalent Output Circuit
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