MAX2402 Evaluation Kit

2

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_________________________Quick Start

The MAX2402 EV kit is fully assembled and factory test-

ed. 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 differen-

tially. 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 differ-

ential 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 appli-

cations, 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.

and GND terminals on the EV kit.

5) Place a shorting termination on the MOD SMA con-

nector 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.

Analysis

1) R1 is a 121

Ω surface-mount resistor on the EV kit

which is parallel with the 50

Ω termination of the

spectrum analyzer. This sets the load of the power

amplifier at 35

Ω, which is a close match to the power

amplifier’s output impedance. As a result, the spec-

trum 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 accu-

rate information.

R1 can be removed, if desired, with about a 0.7dB

reduction in transmitted power due to the load mis-

match. 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 power-

amplifier output to the LO port and cable. When sig-

nal 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 neces-

sary 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 volt-

should be at a minimum when VGC is adjusted below

0.8V. The output power should be at a maximum

4) The BADJ pin is used to control the bias level of the

final stages of the PA. The adjustment range on

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

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

settings and lower frequencies within the 800MHz to

1000MHz range, the power-supply current may

increase unacceptably or the circuit may oscillate.