MAX9981 Evaluation Kit

2

_______________________________________________________________________________________

Quick Start

The MAX9981 EV kit is fully assembled and factory test-

ed. Follow the instructions in the Connections and

Setup section for proper device evaluation.

Test Equipment Required

Table 1 lists the equipment required to verify the opera-

tion of the MAX9981 EV kit. It is intended as a guide

only, and some substitutions can be made.

Connections and Setup

This section provides a step-by-step guide for testing

the basic functionality of the EV kit. As a general pre-

caution to prevent damaging the outputs by driving

high-VSWR loads, do not turn on DC power or RF

signals until all connections are made.

This procedure is specific to operation with an RF input

frequency range of 825MHz to 915MHz, low-side injected

LO for a 100MHz IF. Choose the test frequency based on

the particular system’s frequency plan, and adjust the

following procedure accordingly. See Figure 1 for the

main mixer test setup diagram.

1) Calibrate the power meter for 870MHz. For safety

margin, use a power sensor rated to at least

+20dBm, or use padding to protect the power head

as necessary.

2) Connect 3dB pads to DUT ends of each of the

three RF signal generators’ SMA cables. This

padding improves VSWR and reduces the errors

due to mismatch.

3) Use the power meter to set the RF signal genera-

tors according to the following:

• RFMAIN signal source: -5dBm into DUT at

870MHz (approximately -2dBm before the 3dB

pad)

• LO1 signal source: 0dBm into DUT at 770MHz

(approximately +3dBm before the 3dB pad)

• LO2 signal source: 0dBm into DUT at 771MHz

(approximately +3dBm before the 3dB pad)

4) Disable the signal generator outputs.

5) Connect the RF source (with pad) to RFMAIN.

6) Connect the LO1 and LO2 signal sources to the EV

kit LO inputs.

7) Measure loss in the 3dB pad and the cable that is

connected to IFMAIN. Losses are frequency

dependent, so test this at 100MHz (IF frequency).

Use this loss as an offset in all output power/gain

calculations.

8) Connect this 3dB pad to the EV kit’s IFMAIN con-

nector, and connect a cable from the pad to the

spectrum analyzer.

9) Connect a 50

Ω terminator to the unused RF input

and IF output.

10) Set the DC supply to +5.0V, and set a current limit to

around 500mA if possible. Disable the output voltage

and connect supply to the EV kit through a low inter-

nal resistance ammeter. Enable the supply. Re-adjust

the supply to get +5.0V at the EV kit since there will

be a voltage drop across the ammeter when the

mixer is drawing current.

11) Select LO1 by leaving LOSEL (TP3) unconnected

or connecting it to +5V. If left floating, LOSEL will

be pulled high by an on-board pullup resistor.

12) Enable the LO and the RF sources.

To test the diversity mixer, disable the LO and RF

sources, turn off the DC supply and repeat steps 3

through 12, replacing RFDIV for RFMAIN and IFDIV for

IFMAIN. Be sure to terminate RFMAIN and IFMAIN with

50

Ω terminators. See Figure 2 for diversity mixer test

setup.

Testing the Mixer

Adjust the center and span of the spectrum analyzer to

observe the IF output tone at 100MHz. The level should

be about -5.4dBm (2.6dB conversion gain, 3dB pad

loss). The spectrum analyzer’s absolute magnitude

accuracy is typically no better than ±1dB; therefore,

use the power meter to get an accurate output power

measurement. There will also be a tone at 99MHz which

is due to the LO signal applied to LO2. The amount of

suppression between the 100MHz and 99MHz signals

is the switch isolation.

Connect LOSEL to GND to select LO2. Observe that

the IF output level at 99MHz increases while the

100MHz level decreases.

EQUIPMENT

QTY

DESCRIPTION

HP E3631A

1

DC power supply

Fluke 75 series II

1

Digital multimeter (ammeter)

HP/Agilent 8648B

3

RF signal generators

HP 437B

1

RF power meter

HP 8561

1

Spectrum analyzer

HP 8482A

1

High-power sensor (power head)

3dB pad

4

3dB attenuators

50

Ω termination

2

50

Ω (1W) terminations

Table 1. Test Equipment Required