MAX2402EVKIT-SO View Datasheet(PDF) - Maxim Integrated

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MAX2402EVKIT-SO

MAX2402 Evaluation Kit

Maxim Integrated 

MAX2402 Evaluation Kit

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.

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 termina-

tion and supplying a modulation signal to the SMA

MOD input. The MOD input is linear from approxi-

mately 1.5V to 3.5V, and has a bandwidth of DC to

25MHz. The MOD input is self-biasing to approxi-

mately 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 car-

rier rejection. The MOD input will act as an attenua-

tor 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 resis-

tors. 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 low-

value capacitor, since the high-impedance at the BADJ

node may be sensitive to circuit noise. Although the eval-

uation board uses four layers, it is possible to use two.

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