Maxim Integrated
│
2
www.maximintegrated.com
Evaluates: MAX2831
MAX2831 Evaluation Kit
of 500kHz. Other recommended spectrum analyzer
settings are: Res BW of 1kHz and Ref Level of 10dB.
6) Turn on the RF signal source. The supply current draw
should be approximately 70mA. The output CW tone
at 1MHz should be approximately -2dBm.
Transmit Mode
1) Set the RXTX jumper across pins 1-2 (TX) to enable
the transmitter and disable the receiver. Keep the
ANTSEL jumper at its default position 2-3 (ANT1).
2) Connect TXRF port to the spectrum analyzer. Set the
center frequency of spectrum analyzer to 2437MHz
and span to 10MHz. Other recommended spectrum
analyzer settings are: Res BW of 3kHz, Attenuation of
30dB and Ref Level of 22dB.
3) Connect a 1MHz sinusoid to TXBBI and a 1MHz sinusoid
with a 90° phase shift (or a cosine) to TXBBQ. Set the
input amplitude of each channel to 100mV
RMS
.
4) On the Registers page of the EV kit software, set the
register values to the recommended register setting listed
in the MAX2831 data sheet by clicking the "Defaults"
and "Send All" buttons.
5) On the Entry page, make sure that the "Transmitter
Mode" is set to “normal,” "Baseband Filter Mode
Control" is set to “TX,” and the "RF Frequency" is
tuned to 2437MHz. Set the TX gain to maximum using
the "TX VGA Gain" sliding bar.
6) Enable the output of the baseband signal sources. The
supply current draw should be approximately 88mA.
7) The TX output power at 2438MHz should be
approximately 21dBm. The LO leakage at 2437MHz
should be -16dBm and unwanted sideband at 2436MHz
should be -17dBm.
Note:
CW signals can be replaced by modulated
802.11g/b signals.
Layout Considerations
The EV kit can serve as a guide for board layout. Keep
PCB trace lengths as short as possible to minimize
parasitic inductance. Also, keep decoupling capacitors as
close to the IC as possible with a direct connection to the
ground plane.
Power-Supply Layout
To minimize coupling between different sections of the IC,
use a star power-supply routing configuration with a large
decoupling capacitor at a central V
CC
node. The V
CC
traces branch out from this node, each going to a separate
V
CC
node in the circuit. Place a bypass capacitor as
close as possible to each supply pin. This arrangement
provides local decoupling at each V
CC
pin. Use at least
one throughput per bypass capacitor for a low-inductance
ground connection. Do not share the capacitor ground
vias with any other branch.
JUMPER
SETTING
FUNCTION
RXTX
Pins 2-3
Enable receive mode
Pins 1-2
Enable transmit mode
ANTSEL
Pins 2-3
Default
TXBBBUF/RXBBBUF
Pins 1-2
Enables the buffers
Pins 2-3
Disables the buffers
VREG
Pins 1-2
Short the jumper to provide voltage to the MAX2831 from the linear regulator (U10)
VCCVCO
Pins 2-3
Supply the V
CCVCO
from VREG
Pins 1-2
Supply the V
CCVCO
from the linear regulator (U10)
Table 1. Jumper Functions
