MAX2392EVKIT 查看數據表（PDF） - Maxim Integrated
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MAX2392EVKIT Datasheet PDF : 18 Pages
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MAX2391/MAX2392/MAX2393 Evaluation Kit
3) Calibrate the power meter, with the low-power
head, at 2140MHz. A rough interpolation of the cal
factor does not introduce noticable error, if reading
the cal factor from a table.
4) Set the signal generator for a 2140.18MHz CW
(unmodulated) output at -27dBm, and connect a
3dB pad to the DUT side of the SMA cable. Use the
power meter to set the input power to the DUT at
-30dBm. Use measured attenuators and/or the
signal generator’s internal step attenuators (-40dB)
to reduce the signal to -90dBm.
5) Connect the RF source’s SMA cable and attenua-
tors to the EV kit’s LNAIN SMA input.
6) Connect the BNC cable from either I or Q to the
spectrum analyzer. Connect the other output into
the oscilloscope—be sure to set the oscilloscope’s
inputs to 50Ω, and not 1MΩ. Cable loss at 180kHz
is neglible; as long as cables are about the same
length, no calibration is required at the output to
observe proper signal level as well as proper I/Q
gain-and-phase balance.
7) Set one of the DC supplies to 2.8V and set a current
limit of 100mA (if available). Connect this supply
through the ammeter to “VCC_IC”, and readjust the
supply if necessary to get 2.8V at the IC when pow-
ered up. This supply connection only powers the IC
on the EV kit – read the ammeter to watch IC supply
current for the receiver. Connect another line direct-
ly from the 2.8V supply to “VCC_EXT” to supply the
external logic on the kit. Not having the voltage
drop of the ammeter inline means the voltage is
slightly higher than VCC_IC, but this does not
cause a problem.
8) Set the other supplies for ±5.0V with a current limit
of about 100mA. Connect these supplies to the +5V,
GND, and -5V on the opposite side of the kit. These
are the bipolar supplies for the MAX4444 differential
line drivers that buffer the I/Q outputs. Note that all
GND test points are connected to the same ground
plane—it is only necessary to use one of them.
8) Set the spectrum analyzer to span from DC (mini-
mum sweep) to 2MHz. Set the reference level to
+10dBm.
9) Set the oscilloscope for a sweep rate of about
1µs/div, DC coupling, with an amplitude scale of
about 100mV/div.
Testing the WCDMA Receiver
The power-up default state of the MAX2391 receiver is for:
• LO midband (2140MHz)
• LNA high gain
• Mixer high gain, normal linearity
• Powered on (out of shutdown)
1) Verify that the IC itself is drawing about 32mA (from
VCC_IC). The two MAX4444 differential line drivers
at the baseband outputs should draw about 80mA
from each of their supplies.
2) Use the AGC adjust potentiometer on the board to
set VAGC at +2.2V (maximum gain).
3) Spot-check the VCO tuning voltage (TUNE) to see
that the synthesizer is locked. The voltage should
be about mid-supply with the RFLO running at its
power-up default of 2140MHz. Disconnect any
leads from this before continuing, as the noise pick-
up onto the tuning line directly frequency-modu-
lates the VCO, and degrades LO phase noise.
4) Observe the 180kHz tone on the spectrum analyzer.
Adjust AGC to to achieve a -3.5dBm output level.
5) The on-board TCXO has a fine-tuning control—the
other potentiometer on the EV kit allows for external
temperature compensation of the TCXO to further
decrease frequency error. Adjust the TCXO poten-
tiometer if desired to bring the output tone exactly
to 180kHz.
6) Observe the other output on the oscilloscope. At
these input power levels, the SNR is typically much
too low to see the output tone through the noise. If
available, use the internal low pass filter option
(often 20MHz) and lots of averaging.
7) To make a gain/phase error measurement, connect
both outputs to the scope. Increase the input power
to about -50dBm, and back off the AGC until the
outputs are swinging about 0.42VP-P. Again, use
digital averaging to get both I and Q sinusoids visi-
ble on the scope. If automated measurements for
phase and amplitude are not available, use the cur-
sors to make the measurement. Calculate phase
error in degrees, and gain error in dB, and verify
that the results are better than 2 degrees and
0.6dB, respectively.
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