MAX3509 Evaluation Kit

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5

where:

160kHz bandwidth

trum analyzer

GAMP = Gain of the postamplifier in dB

If the spectrum analyzer being used does not have a

noise marker function, corrections must be made to

account for the IF bandwidth used to make the mea-

surement. Consult the user’s manual for your spectrum

analyzer for details. Once the correction is made, the

value read from the spectrum analyzer can be convert-

ed to a noise density (dBm/Hz), and the above formula

can be used.

Noise can now be measured at various gains. Output

noise in transmit-disable mode is insignificant.

Layout Considerations

The MAX3509 evaluation board can serve as a guide

for your board layout. Particular attention should be

paid to thermal design and to the output network.

The MAX3509 package exposed paddle (EP), labeled

GND2, conducts heat out of the part and also provides

a low-impedance electrical connection. The EP must be

attached to the PC board ground plane with a low ther-

mal and electrical impedance contact. Ideally, this

would be provided by soldering the backside package

contact directly to a top metal ground plane on the PC

board. Alternatively, the EP could be connected to a

ground plane using an array of plated vias directly

below EP. The EV kit incorporates both of these meth-

ods.

The output circuit that connects OUT+ and OUT- (pins

16 and 17) to the output transformer (T2) should be as

symmetrical as possible to reduce second-order distor-

tion. In addition, the inductance of this path should be

kept low to minimize gain rolloff at high frequencies.

Component Suppliers

Note: Please indicate that you are using the MAX3509 when

contacting these suppliers.

SUPPLIER

PHONE

FAX

AVX

803-946-0690

803-626-3123

M/A-COM

978-442-5000

978-442-4178

Murata

814-237-1431

814-238-0490

Coilcraft

847-639-6400

847-639-1469