Integration Guide

LEON-G100/G200 - System Integration Manual
GSM.G1-HW-09002-F3 Preliminary Design-In
Page 73 of 101
Rank
Function
Pin(s)
Layout
Remarks
1
st
RF Antenna In/out
Very
Important
Design for 50 characteristic impedance.
See section 2.2.1.1
2
nd
DC Supply
Very
Important
VCC line should be wide and short. Route away
from sensitive analog signals. See section 2.2.1.2
3
rd
Analog Audio
Careful Layout
Avoid coupling with noisy signals.
See section 2.2.1.3
Audio Inputs
MIC_BIAS1, MIC_GND1,
MIC_BIAS2, MIC_GND2
Audio Outputs
SPK_P, SPK_N, HS_P
4
th
Ground
GND
Careful Layout
Provide proper grounding.
See section 2.2.1.4
5
th
Charger
V_CHARGE,
CHARGE_SENSE
Careful Layout
Check Charger line width.
See section 2.2.1.5
6
th
Sensitive Pin:
Careful Layout
Avoid coupling with noisy signals.
See section 2.2.1.6
Backup Voltage
V_BCKP
A to D Converter
(If implemented)
ADC1
Power On
PWR_ON
7
th
Digital pins:
Common
Practice
Follow common practice rules for digital pin
routing
See section 2.2.1.7
SIM Card Interface
VSIM, SIM_CLK, SIM_IO,
SIM_RST
Digital Audio
I2S_CLK, I2S_RXD,
I2S_TXD, I2S_WA
DDC
SCL, SDA
UART
TXD, RXD, CTS, RTS, DSR,
RI, DCD, DTR
External Reset
RESET_N
General Purpose I/O
GPIO1, GPIO2
Table 29: Pin list in order of decreasing importance for layout design
2.2.1.1 RF Antenna connection
The RF antenna connection pin ANT is very critical in layout design. The PCB line must be designed to provide
50 Ω characteristic impedance and minimum loss up to radiating element.
Provide proper transition between the ANT pad to application board PCB
Increase GND keep-out (i.e. clearance) for ANT pin to at least 250 µm up to adjacent pads metal definition
and up to 500 µm on the area below the Data Module, as described in Figure 44
Add GND keep-out (i.e. clearance) on buried metal layers below ANT pad and below any other pad of
component present on the RF line, if top-layer to buried layer dielectric thickness is below 200 µm, to reduce
parasitic capacitance to ground (see Figure 44 for the description keep-out area below ANT pad)
The transmission line up to antenna connector or pad may be a micro strip or a stripline. In any case must be
designed to achieve 50 Ω characteristic impedance
Microstrip lines are usually easier to implement and the reduced number of layer transitions up to antenna
connector simplifies the design and diminishes reflection losses. However, the electromagnetic field extends
to the free air interface above the stripline and may interact with other circuitry
Buried stripline exhibits better shielding to incoming and generated interferences. Therefore are preferred for
sensitive application. In case a stripline is implemented, carefully check that the via pad-stack does not
couple with other signals on the crossed and adjacent layers
Minimize the transmission line length; the insertion loss should be minimized as much as possible, in the
order of a few tenths of a dB
The transmission line should not have abrupt change to thickness and spacing to GND, but must be uniform
and routed as smoothly as possible
ANT
VCC