Texas Instruments TRF1208-EVM, User Manual, Page: 3 / 17

3. Single tone measurement setup recommendation:
a. Connect an RF signal generator to input SMA connector, J4.
When measuring single tone distortion, use an RF band pass filter as shown in Figure 1-1 .
b. The RF signal generator used must support up to 12-GHz signal frequency for testing out the TRF1208
EVM.
c. The TRF1208 device input is 50-Ω in the pass-band.
To minimize signal reflections due to impedance mismatch, TI recommends using an attenuator pad of
approximately 3-dB to 6-dB between the source and J4 SMA input.
d. The EVM outputs are fully differential (or 180° out-of-phase) at J5 and J6 SMA connectors.
The TRF1208 device has low output impedance at dc and low frequencies.
e. When connecting to a spectrum analyzer, the differential signal out of the EVM should be converted to a
single-ended signal using an external passive balun as shown in Figure 1-1 .
Usage of an attenuator pad of approximately 3-dB to 6-dB is recommended at the three terminals of the
passive balun to minimize reflections.
f. Lastly, it is recommended to properly characterize and account for the insertion loss of RF coaxial (coax)
cables, attenuator pads, and passive baluns to measure accurate gain and power levels for the device.
4. Matching considerations:
a. TRF1208 is a wide-band amplifier and it expects 50-Ω input matching over its operating bandwidth upto
about 12 GHz. A signal generator or Noise Source that drives this EVM will have 50-Ω impedance
over a wide band width. But if this EVM is driven by a narrow-band driver or a source that has non
50-Ω matching, then there may be instability issues with the amplifier. To avoid such issues, additional
matching may be require at the input. See the
TRF1208 Single Channel, 10 MHz to 8 GHz 1-dB BW,
Single Ended to Differential Amplifier data sheet for more information.
b. As mentioned earlier, the TRF1208 device has low output impedance and a zero-ohm series resistors
are used in the EVM. When the EVM outputs are connected to a balun, it is recommended to use
attenuator pads to minimize reflections.
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SBOU266 – SEPTEMBER 2021
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TRF1208 Evaluation Module 3
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