User Guide

CCS Technical Documentation System Module
RH-25
Issue 1 10/2003 ©Nokia Corporation Confidential Page 23
EAR Lines
EAR lines are output signals, also routed on layer 2 and 7, to obtain immunity for con-
ducted emission from UEM. Internal EAR lines are EMC/ESD protected by radiated fields
from the earpiece by the low-impedance signal path in the PWB.
The same PWB outline has been implemented for the SALT speaker. Low ohm coils induc-
tors are used in series with the speaker for immunity against incoming fields from the
speaker.
Charger Lines
Ground from the charger is connected directly to common PWB ground for low imped-
ance path to the battery. The positive charger line will be ESD, EMC, and short-circuit
protected by appropriate circuits.
HEADINT
This line is EMC/ESD protected by routing on shielded layer 2 and by placement of resis-
tor R154 close to the bottom connector.
Battery Supply Filtering
Battery supply lines to the UEM IC are filtered with LC filter. These filters provide immu-
nity against conducted RF noise
System Connector
The immunity strategy concerning the bottom connector lines is to shield all lines to this
part in order to prevent radiation in the phone itself when external accessory is con-
nected and to prevent radiated fields from disturbing the lines as well. Appropriate dis-
crete filters close to the bottom connector are implemented for EMC and ESD protection.
Mechanical Shielding
RH-25 has metal shield over RF parts and BB parts to provide immunity for internal radi-
ation and immunity for external fields.
EMC Strategy
The RH-25 phone must comply with the given CE requirements concerning EMC and ESD.
The goal is to pass internal SPR requirements. Therefore attention has been paid to
obtaining immunity in the PWB layout itself, and the implementation of filters in the cir-
cuit design.
Requirements for EMC and ESD:
• CE requirements for EMC and ESD according to ETS 300 342-1
• Internal requirements for EMC and ESD are according to SPR4
The baseband EMC strategy is divided into electrical and mechanical items. All electrical
guide lines, clocks, and high-speed signals should be routed in inner layers and away
from the PWB edges. Clock signals distributed to other circuits should have series resis-