Analog Devices EVAL-ADRF5345, User Manual

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User Guide EVAL-ADRF5345
EVALUATION BOARD HARDWARE
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OVERVIEW
The ADRF5345-EVALZ is a connectorized board, assembled with
the ADRF5345 and its application circuitry. All components are
placed on the primary side of ADRF5345-EVALZ. An assembly
drawing for the ADRF5345-EVALZ is shown in Figure 10 , and an
evaluation board schematic is shown in Figure 9 .
BOARD LAYOUT
The ADRF5345-EVALZ is designed using RF circuit design techni-
ques on an 8-layer printed circuit board (PCB). The PCB stack-up is
shown in Figure 2 .
Figure 2. Evaluation Board Stack-Up
The outer copper layers are 2 oz (2.7 mil) thick and the inner layers
are 1 oz (1.3 mil) thick.
The top dielectric material is 10 mil Rogers 4350B, which provides
50 Ω controlled impedance and optimizes the high frequency per-
formance. All RF traces are routed on the top layer, and the second
layer is used as the ground plane for RF transmission lines. The
remaining six layers are also ground planes filled with FR4 material
to manage the thermal rise during high power operations, and
are supported with dense and filled vias to the PCB bottom for
thermal relief. The overall board thickness is approximately 63 mil
for mechanical strength.
The RF transmission lines are designed using a coplanar wave-
guide (CPWG) model with a width of 18 mil and ground spacing
of 13 mil to have a characteristic impedance of 50 Ω. Ground via
fences are arranged on both sides of a coplanar waveguide to
improve isolation between nearby RF lines and other signal lines.
The exposed ground pad of the ADRF5345, which is soldered
on the PCB ground pad, is the main thermal conduit for heat
dissipation. The PCB ground pad is densely populated with filled,
through vias to provide the lowest possible thermal resistance path
from the top to the bottom of the PCB. The connections from the
package ground leads to ground are kept as short as possible.
POWER SUPPLY AND CONTROL INPUTS
The ADRF5345-EVALZ has one power supply input, three control
inputs, and a ground, as shown in Table 1 . The dc test points are
populated on VDD, V1, V2, LS, and GND. A single 5 V supply
is connected to the dc test points on VDD. Ground reference can
be connected to GND. Connect the control inputs, V1, V2, and
LS, to 3.3 V or 0 V. The typical total current consumption for the
ADRF5345 is 2 mA.
The VDD supply pin of the ADRF5345 is decoupled with 100 pF
and 4.7 μF capacitors, and the control pins of the ADRF5345 are
decoupled with a 100 pF capacitor.
Table 1. Power Supply and Control Inputs
Test Points
Description
VDD Supply voltage
V1 Control Input 1
V2 Control Input 2
LS Logic select
GND Ground