Evaluation Board Hardware; Overview; Board Layout - Analog Devices EVAL-ADRF5714 User Manual

User Guide EVAL-ADRF5714

EVALUATION BOARD HARDWARE

OVERVIEW

The ADRF5714-EVALZ is a connectorized board, assembled with
the ADRF5714 and its application circuitry. All components are
placed on the primary side of the ADRF5714-EVALZ. An assembly
drawing for the ADRF5714-EVALZ is shown in Figure 8, and an
evaluation board schematic is shown in Figure 7.

BOARD LAYOUT

The ADRF5714-EVALZ is designed using RF circuit design techni-
ques on a 4-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 1.5 oz (2.2 mil) thick and the inner
layers are 0.5 oz (0.7 mil) thick.
The top dielectric material is 12 mil Rogers 4003, which provides 50
Ω controlled impedance and optimizes the high frequency perform-
ance. 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 two 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 62 mil
for mechanical strength.
The RF transmission lines are designed using a coplanar wave-
guide (CPWG) model with a width of 16 mil and ground spacing
of 6 mil to have a characteristic impedance of 50 Ω. Ground
via fences are arranged on both sides of the CPWG to improve
isolation between nearby RF lines and other signal lines.
The exposed ground pad of the ADRF5714, 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.
analog.com Rev. 0 | 3 of 9