8 of 10
RF3330
Rev A4 DS060908
7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical
support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
offset needs to be applied to the signal generator. The formulas used to calculate this offset are given below in Equations 1
through 3. It should be noted that the unbalanced 1000
Ω load is used, because all data in the datasheet is referenced to sin-
gle-ended operation. Using a spectrum analyzer probe, the actual offset measured was 7.5dB, and this is what is used for the
amplitude offset in the signal generator.
Mismatch Loss (ML)=-10*log(1-|
ΓL|2)Eq. 1
ΓL =(Z-Z0)/(Z+Z0)Eq. 2
ML=-10*log(1-[(1000-50)/(1000+50)]2)=7.4dB
Eq. 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 trans-
former, 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))=-31.7dBEq. 4
3330410 Evaluation Board
1:1
Transformer
Frequency =
1 MHz to
150 MHz
Spectrum Analyzer
Resistive
Match
Mini-Circuits
ZMSCJ-2-1
Divider
Frequency =
1 MHz to
150 MHz
Frequency =
1 MHz 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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