Antenna Interface; Power Supply; Sim Card Interface; Audio Interface - SIM Tech SIMCom SIM800C Hardware Design

5.2.1

Antenna Interface


The length of trace between pin output and connector should be as short as possible;

Do not trace RF signal over across the board;

The RF signal should be far away from SIM card, power ICs.
5.2.2

Power Supply


Not only VBAT but also return GND are very important in layout;

The positive line of VBAT should be as short and wide as possible;

The correct flow from source to VBAT pin should go though Zener diode then huge capacitor;

Pin 36 and Pin37 are GND signals, and shortest layout to GND of power source should be designed;

There are 10 GND pads in middle of module; these pads could enhance the GND performances. On
the upper layer of these pads, do not trace any signal if possible.
5.2.3

SIM Card Interface


SIM card holder has no anti-EMI component inside. Thus SIM card interface maybe interfered,
please pay more attention on this interface during layout;

Ensure SIM card holder is far way from antenna or RF cable inside;

Put SIM card holder near the module, as nearer as possible;

Add ESD component to protect clock, data, reset and SIM_VDD signals which should be far away
from power and high-speed-frequency signal.
5.2.4

Audio Interface


The signal trace of audio should far away from antenna and power;

The audio signal should avoid to parallel with VBAT trace.
5.2.5

Others


It is better to trace signal lines of UART bunched, as well as signals of USB.
SIM800C_Hardware_Design_V1.00 42
Smart Machine Smart Decision
2014-10-30