Preliminary
3-38
RF3322
Rev A2 010518
3
L
A
Hardware Setup
Gain and Harmonic Distortion Test Setup
To test the gain of the RF3322 PCBA, connect a low-
pass or band-pass filter to the output of the signal gen-
erator. Use a filter just above the frequency you want to
test. The filter is used to attenuate any harmonics out-
put by the signal generator. Connect the signal genera-
tor to the power meter and measure the power.
Compare with modulation enabled and disabled to
make sure the meter was measuring average rather
than peak power. No more than 0.2dB difference in
power should be observed. An offset on the signal gen-
erator may be needed to match the level shown on the
power meter. The signal generator should then be con-
nected directly to a spectrum analyzer. Make sure the
output of the signal generator is the same as the input
read by the spectrum analyzer. Adjust the offset of the
spectrum analyzer until the signal out is the same as
the signal in on the spectrum analyzer. Turn off the RF
and modulation. Check positioning of the jumpers on
the board. Refer to the PCBA section of this applica-
tion note to verify proper positions. Connect the output
of the signal generator to J2: RFIN of the PCB. Con-
nect J7: RFOUT to the spectrum analyzer. Ensure that
you are accounting correctly for the losses in the 75
to 50
conversion at the output of the device; there is
an output voltage loss of 3.5dB for the evaluation
board in its standard configuration (see output stage
circuit description). Connect one end of the serial cable
into the computer and the other end into J1 of the PCB.
Connect +5.0V
DC
into V+ and ground into GND(JP1).
Turn on the DC power and turn on RF from the signal
generator. Set the GCW to 58 and make sure TX
Enable is checked. The amplified signal should be dis-
played on the spectrum analyzer. The harmonics can
also be viewed with this setup. As you change the
GCW from 58 to 0 (in steps of one), there will be a 1dB
change in the output of the PCB.
ACPR Test Setup
To test the ACPR of the RF3322 PCBA set modulation
to:
QPSK
2Bits/Sym
160ksps
α
=0.25
PRBS-20bit Data
4
CLK Line
5
SHUTDOWN Line
3
Data Line
6
TX Enable Line
25 Pin D-Connector (Back View)
RF3322 PCBA Cable
2
CS Line
18
Ground
Figure 3. Cable Configuration
Figure 4. On-Screen Display