Maxim MAX2402EVKIT-SO Evaluation kit Datasheet

MAX2402 Evaluation Kit
The MAX2402 evaluation kit (EV kit) simplifies evaluation of the MAX2402 transmitter. The EV kit enables the
testing of all MAX2402 functions with no additional support circuitry and with minimal equipment.
Features
♦ Low-Cost, Flexible Transmitter
♦ More than 100mW of Output Power
♦ Operates from 800MHz to 1000MHz
♦ Single +5V Supply
♦ Easy Testing of All MAX2402 Features
Component List
DESIGNATION QTY
DESCRIPTION
C1
1
10µF, 25V, 10%, tantalum capacitor
C2
1
0.1µF, 50V, 10% ceramic capacitor
C3, C4, C5
3
39pF, 50V, 5% ceramic capacitors
C6
1
150pF, 50V, 5% ceramic capacitor
C7, C9, C12
2
0.01µF, 50V, 10% ceramic capacitors
C8
1
100pF, 50V, 5% ceramic capacitor
C10
1
220pF
L1
1
27nH, 20% inductor
Coilcraft 0805CS-270XMBC
L2
1
47nH, 20% inductor
Coilcraft 0805CS-470XMBC
LO+, LOMOD, OUT
4
Female SMA connectors
R1
1
121Ω, 1% resistor
R2, R5
2
100Ω, 5% resistors
R3, R4
2
49.9Ω, 1% resistors
R6, R7
2
51Ω, 5% resistors
R8
1
1kΩ, multi-turn potentiometer
U1
1
MAX2402EAP
W1–W4
4
2-pin headers
None
4
2-pin shunts
Ordering Information
PART
MAX2402EVKIT-SO
TEMP. RANGE
-40°C to +85°C
BOARD TYPE
Surface Mount
EV Kit
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
Evaluates: MAX2402
General Description
Evaluates: MAX2402
MAX2402 Evaluation Kit
_________________________Quick Start
The MAX2402 EV kit is fully assembled and factory tested. Do not turn on the power until all connections
are made.
Test Equipment Required
• Signal source, sine-wave generator with range up to
1000MHz (example: HP8656B)
• Signal source, function generator with range up to
10MHz
• Spectrum analyzer with range up to 4GHz (example:
TEK2755AP)
• Power supply capable of 5V, 300mA output with
current limit
Connections and Signal Conditions
1) Verify that all shunts are across jumpers W1–W4.
2) The LO port can be driven single-ended or differentially. For single-ended drive, connect an SMA cable
from the 1000MHz signal source to the LO+ SMA
input on the EV kit. For differential drive, install a
220pF ceramic capacitor (not provided) at site C11.
Using SMA cables, connect the signal source to the
LO+ and LO- inputs through a balun with sufficient
bandwidth.
The EV kit was designed for single-ended or differential LO drive. In your final layout, capacitors C10
and C11 are not required. For single-ended LO drive
applications, ground the unused LO port as close to
the package as possible. For differential drive applications, connect LO lines directly to LO port pins.
Coupling capacitors are not required, as the LO
ports are internally AC coupled.
3) Connect an SMA cable from the spectrum analyzer
to the OUT SMA on the EV kit.
4) Connect the power supply to the appropriate VCC
and GND terminals on the EV kit.
5) Place a shorting termination on the MOD SMA connector to put the mixer in a fully on position.
6) Set LO power to 0dBm and frequency to 900MHz on
the signal source. Do not apply a signal to the DUT
yet, if you have control of this function.
7) Set the spectrum analyzer’s dynamic range for a top
limit of 30dBm, and set the frequency range for an
appropriate setting to view the output.
8) Set the power supply to 5.0V and set the current limit
to 300mA. Apply power.
2
Analysis
1) R1 is a 121Ω surface-mount resistor on the EV kit
which is parallel with the 50Ω termination of the
spectrum analyzer. This sets the load of the power
amplifier at 35Ω, which is a close match to the power
amplifier’s output impedance. As a result, the spectrum analyzer will display an output power level
which is 1.5dB below the actual transmitted power.
As long as this resistor is on the EV kit, 1.5dB must
be added to any displayed power levels to get accurate information.
R1 can be removed, if desired, with about a 0.7dB
reduction in transmitted power due to the load mismatch. The output power (with 1.5dB added to the
displayed power) should be at least 20dBm. (Note:
Before signal is applied to the LO port there may be
a parasitic oscillation on the EV board. This is
caused by parasitic feedback from the poweramplifier output to the LO port and cable. When signal is applied to the LO port, this oscillation will
abate.)
2) The output power can be observed for the 800MHz
to 1000MHz LO input range and over the prescribed
input power levels. (Near 800MHz, it may be necessary to adjust BADJ to higher than 2.5V to maintain
stability.)
3) To observe the effects of the VGC voltage on output
power, connect an adjustable supply to the VGC test
point on the EV kit and remove the VGC jumper (W3).
This supply can now be adjusted and the output
power can be observed as a function of VGC voltage. The VGC range is 0V to VCC. The output power
should be at a minimum when VGC is adjusted below
0.8V. The output power should be at a maximum
when VGC is adjusted above (VCC - 0.5V).
4) The BADJ pin is used to control the bias level of the
final stages of the PA. The adjustment range on
BADJ is 0V to VCC, with 0V representing the greatest
bias current and 5V the least. More bias current will
result in more output power, less efficiency, and less
distortion. The intended configuration for this pin is a
single resistor pull-up or pull-down to VCC or GND,
respectively. The value of this resistor will determine
the bias voltage at the BADJ pin. See Table 1 in the
MAX2402 data sheet for a guide to resistor use at
the BADJ input.
The MAX2402 BADJ input is self biasing to about
VCC/2 and can be left open. At low BADJ voltage
settings and lower frequencies within the 800MHz to
1000MHz range, the power-supply current may
increase unacceptably or the circuit may oscillate.
_______________________________________________________________________________________
MAX2402 Evaluation Kit
5) The MAX2402 SHDN pin connects to VCC through a
jumper and 100Ω. To test the shutdown function,
ensure that either W1 or W2 is removed, which will
prevent current draw through R6, R7, and R8. When
the SHDN jumper is removed and the SHDN test
point is grounded, the supply current should drop
below 1µA.
6) The modulated spectrum can be examined on the
spectrum analyzer by removing the shorting termination and supplying a modulation signal to the SMA
MOD input. The MOD input is linear from approximately 1.5V to 3.5V, and has a bandwidth of DC to
25MHz. The MOD input is self-biasing to approximately VCC/2. Any offset at the MOD input from a
symmetric signal around the self-bias voltage will act
as an offset and cause less than optimal carrier
rejection. Capacitive coupling into the MOD input
will eliminate this situation and result in optimum carrier rejection. The MOD input will act as an attenuator if it is left open.
Adjustments and Control
VGC
The VGC jumper (W3) shorts the VGC input of the
MAX2402 to VCC. The VGC test point can be used to
manipulate the gain control voltage. The VGC jumper
(W3) should be removed before trying to control this
VGC voltage. It connects to VCC when in place.
SHDN
The SHDN jumper (W4) shorts the SHDN input to VCC
to keep the part in normal operating condition. The
SHDN test point can be used with a controlling voltage
to power down the MAX2402. The SHDN jumper (W4)
should be removed when adjusting the voltage on the
test pin. It connects to VCC when in place.
BADJ
The two bias adjust jumpers connect either end of the
1kΩ potentiometer to VCC and GND through 50Ω resistors. The wiper on the potentiometer has been factory
adjusted to provide 2.5V to the BADJ input on the
MAX2402. The BADJ test point is for monitoring the
BADJ voltage. The BADJ jumpers (W1, W2) connect R8
to VCC and GND, respectively. BADJ voltage is altered
by adjusting the R8 potentiometer.
Layout Considerations
The evaluation board can serve as a guide for board
layout. C3, C4, and C5 should be small surface-mount
capacitors, placed directly from each VCC pin to the
adjacent ground. Place them as close to the MAX2402
as possible, and make connections directly to the pins
(not through vias or long traces). C6, C7, and C8 should
also be surface mount. C7 should be next to C3. C8 and
C9 should be located at the VCC terminal of choke L2. If
the LO is driven single-ended, ground the unused LO
port. If a single resistor is used to bias BADJ, it may be
necessary to AC couple BADJ to ground with a lowvalue capacitor, since the high-impedance at the BADJ
node may be sensitive to circuit noise. Although the evaluation board uses four layers, it is possible to use two.
_______________________________________________________________________________________
3
Evaluates: MAX2402
At these lower frequencies, more than 20dBm of
power can easily be obtained with BADJ set at 3V or
above (see the BADJ Input section of the MAX2402
data sheet).
Removing the VCC jumper (W1) on the EV kit will
connect BADJ to GND, while removing the GND
jumper (W2) will connect BADJ to VCC. Removing
both will cause BADJ to rely on its internal bias.
Evaluates: MAX2402
MAX2402 Evaluation Kit
VCC
W4
R2
100Ω
C5
39pF
W3
C4
39pF
4
R5
100Ω
VCC
C7
0.01µF
VCC
OUT
R6
51Ω
VGC
W1
SHDN
1
C12
0.01µF
9
10
R8
1k
VGC
2
MOD
R7
51Ω
LGND
6
LO+
MOD
LO+
R4
49.9Ω
7
LOR3
49.9Ω
16
LO-
L2
47nH
C2
0.1µF
C1
10µF
25V
C8
100pF
C9
0.01µF
14
OUT
C6
150pF
11
R1
121Ω
L1
27nH
BADJ
U1
GND
MAX2402
GND
GND
C10
220pF
C11
OPEN
OUT
SHDN
BADJ
W2
12
VCC
C3
39pF
19
GND
3
5
8
GND
13
GND
15
GND
17
GND
18
GND
20
Figure 1. MAX2402 EV Kit Schematic
4
_______________________________________________________________________________________
MAX2402 Evaluation Kit
Figure 3. MAX2402 EV Kit PC Board Layout—Component Side
Figure 4. MAX2402 EV Kit PC Board Layout—Solder Side
Note: Ground layers 2 and 3 not shown.
_______________________________________________________________________________________
5
Evaluates: MAX2402
Figure 2. MAX2402 EV Kit Component Placement Guide—
Component Side
Evaluates: MAX2402
MAX2402 Evaluation Kit
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
6 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1996 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
Similar pages