All Rights reserved, No Spreading without GOSUNCN Permission
40
Hardware Development Guide
ME3616
transmission line;
The ground surrounding the antenna line on PCB has to be strictly connected to the main Ground Plane by means of via
holes (once per 2mm at least), placed close to the ground edges facing line track;
Place EMI noisy devices as far as possible from modules antenna line;
Keep the antenna line far away from the module power supply lines;
3.4.
S
UGGESTIONS FOR
EMC
&
ESD
D
ESIGN
3.4.1.
EMC
D
ESIGN
R
EQUIREMENTS
During the design of the whole device, the user needs to fully consider the EMC problem caused by the signal integrity and
power integrity.
During the product design, it is better to separate the module from the mainboard PCB, instead of installing the module on the
ground of the mainboard. If they cannot be separated, the module should be far from modules and components that might generate
EMI, such as chip and memory, power interface, and data cable interface.
Because the mainboard of PAD, CPE, and Internet laptops does not have a shielding cover, as that of mobile terminals, to shield
most circuits to avoid overflow of electromagnetic interference, you can spray conductive paint on the surface on non-antenna areas
within the structural components above and below the mainboard, and the conductive paint should be connected to the ground on
the mainboard by several points to shield electromagnetic interference.
Besides, data cables of the LCD and the camera might introduce interference signals, which affect the receiving performance of
the antenna. Thus, it is necessary to wrap conductive cloth around the two data cables and connected them to the ground.
RF cables of the antenna should be far from modules and components that might generate EMI, such as chip and memory,
power interface, and data cable interface. The wiring of RF cables should be close to the ground of the mainboard.
During the layout and wiring of peripheral circuits, for the wiring of power and signal cables, keep a distance of 2 times of the
line width, so as to effectively reduce the coupling between signals and keep a clean reflux path for the signal.
During the design of peripheral power circuits, the de-coupled capacitor should be placed closed to the module power PIN, the
high-frequency high-speed circuit and the sensitive circuit should be placed far away from the border of PCB. They should better be
separated during layout, so as to reduce the interference between them and protect the sensitive signal.
For the circuit or device on the side of system board that might interfere with the module, it should be shielded during design.
3.4.2.
ESD
D
ESIGN
R
EQUIREMENTS
Module is embedded on the side of system board, so the user needs to make the ESD protection during design. For the key
input/output signal interface, such as the (U)SIM card signal interface, the ESD device should be placed closely for protection.
Besides, on the side of main board, the user should reasonably design the structure and PCB layout, guarantee that the metallic
shielding shell is fully grounded, so as to leave a smooth discharge channel for ESD.
3.5.
T
EST
M
ETHODS FOR
W
HOLE
-S
ET
A
NTENNA
OTA
Figure below is the diagram of OTA test system of CTIA. The system is mainly composed of test chamber, high-precision
positioning system and its controller, Windows based PC running test software and RF test instruments with automatic test program.
The main RF instruments are integrated RF test equipment, Spectrum Analyzer, Network Analyzer.
The radio equipments, Relay Switch Unit and PC with automatic test software are communicated via GPIB interface.