ADL5240ACPZ-R7 datasheet(23/28 Pages) AD

23 / 28 page

Data Sheet

ADL5240

Rev. A | Page 23 of 28

EVALUATION BOARD

The schematicof the ADL5240 evaluation boardis shown in

Figure 41, the evaluationboardconfigurationoptionsaredetailed

in Table 8, and the layout of the ADL5240 evaluation board is

shown in Figure43 and Figure44. Each RFtrace on theevaluation

board has a characteristicimpedance of 50 Ω and is fabricated

on Rogers3003 material. In addition, each trace is a coplanar

waveguide(CPWG)witha width of25 mils, a spacing of20 mils,

and a dielectric thickness of 10 mils. The input to and output

from theDSA and amplifier shouldbeac-coupled with capacitors

of appropriatevaluesto ensurethe broadband performance.

The bias to the amplifier is provided by connecting a choke to

the AMPOUT pin. Bypassing capacitors arerecommendedon

all supply lines to minimize the RF coupling. The DSA and the

amplifier can be individually biased or connected to the VDD

plane using Resistors R2 and R1.

The ADL5240 can be operated in two ways: the amplifier can

precede the DSA (AMP-DSA loopconfiguration)or the DSA

can precede the amplifier (DSA-AMP loop configuration). The

evaluation boardcan be configured to handleeitheroption. In

normal operation, R12 and R13 are open, and R10 and R11 are

0 Ω and are used to terminateany RF coupling onto the bypass

trace. ToconfiguretheADL5240 in AMP-DSA loopconfiguration,

R12 should be replaced with a capacitor, R13 should be replaced

with a 0 Ω resistor,andR10 andR11 shouldbeleft open.Similarly,

to configure the ADL5240 in the DSA-AMP loop configuration,

R16 should be replaced with a capacitor, R17 should be replaced

with a 0 Ω resistor, and R14 and R15 should be left open.

The digital signal traces incorporate a footprint for an RC filter

to prevent potential noisefromcouplingontothesignal.In normal

operation, series resistors are0 Ω and shunt resistorsand

capacitors are open.

The evaluation board is designed to control DSA in either

parallel or serial mode by connecting the SEL pin to the supply

or ground by a switch.

For adjusting attenuation at DSA, the ADL5240 can be

programmedin two ways: through the on-board USBinterface

from a PC USB port, or through an SDP board, which will

become the Analog Devicescommon control board in the

future. The on-board USBinterfacecircuitry of the evaluation

board is powered directly by the PC. USB based programming

software is availableto download fromthe ADL5240 product

page at www.analog.com. Figure45 shows the window of the

programming softwarewhere the user selects serial or parallel

mode for the attenuation adjustmentat DSA. The selection of

the mode in the window should match the mode of the

evaluation boardswitch.

It is highly recommended to referthe evaluation boardlayout

for the optimal and stableperformanceof each blockas well as

for the improvement of thermal efficiency.

ADL5240ACPZ-R7 数据表(PDF) 23 Page - Analog Devices

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