The EMI Solution for Cellular Phone
Agenda
1.Internal Interference
1) Receiving Sensitivity Restraint
2) Decrease in RF Limit Level for Receiving
2. Emission
3. Immunity
4. TDMA Noise
Test & Measurement Facilities
Anechoic Chamber
EMI TESTER
GSM TEST SET
8922P
UHF-TEM CELL
CDMA TEST SET
E5515C
1. Internal Interference 1) Receiving Sensitivity Restraint
Internal Interference
CAMERA TV Tuner
Bluetooth IrDA
Many Function being installed
CH
Level
RF Signal
-106dBm
Less
Many
Noise
Function
Movie Mail TV Phone
Color LCD (QVGA)
Current Functions -Voice -e-mail...
EXT Memory
USB
RF MMIC
FPCB
Base Band IC
PA
LCD Control IC
Memory
Base Band IC
Power Line (DC-DC Output)
-5051015202530820
830
840
850
860
870
Frequency [MHz]
N o i s e L e v e l [d B u V ]
-5051015202530820
830
840
850
860
870
Frequency [MHz]
N o i s e L e v e l [d B u V ]
-5051015202530820
830
840
850
860
870
Frequency [MHz]N o i s e L e v e l [d B u V ]
-5051015202530820
830
840
850
860
870
Frequency [MHz]
N o i s e L e v e l [d B u V ]
Digital Noise in Base Band Block
Measure ER, disconnecting LCD
Improved Cause : LCD Lines EMI Suppression in
Conduction Path
Not improved, EMI Suppression in BB Block
What Phenomenon?
Only Specific Channel Multiple Channels Source : CLK
Confirm Base Freq. of Harmonics
Power Line Data Lines CLK Line
LCD Power
Line LCD Signal
Lines GND Identify IC operating at the Frequency
(Identify IC radiating High Level Noise)
Identify IC radiating High Level
Noise in Base Band Block
Which Line High Level Noise is conducting on?
Source : Data / Power Line Observed Receiving Sensitivity Restraint
ER: Error Rate
BB: Base Band
EMI Suppression
in Noise Source
Power Line
Data Lines
CLK Line GND Insert EMI
Filter / Resistor Insert EMI Filter
Insert EMI Filter
NFM Series
BLA Series
NFL Series
NFM Series NFA Series
Change position of
GND to return noise current to IC effectively.
GND
GND
Remove Cap which does not return noise current to IC
Vcc GND
ベースバンド
IC
L C D
Base Band IC
Memory
Base Band IC By-pass Cap
Memory
Widen GND Pattern.Connect with GND Layer
by through hole
GND Pattern
Stabilize Return
GND
Resistor
LCD Power
Line LCD Signal Lines Insert EMI Filter / Adjust By-pass
Cap.Insert EMI Filter BLM Series
Mapped Noise Radiation (GSM
Band) from FPCB with EMI Tester
20253035404550556065800
850
900
950
1000
Frequency [MHz]
N o i s e L e v e l [d B u V ]
Mapped at this Freq.
RF MMIC
LCD
FPCB
Base Band IC
PA
Radiated from FPCB, Received by Antenna
Noise Conducting on LCD Lines
Mechanism
Receiving Sensitivity Restraint of LCD
Any Solutions?
FPCB
IC
LCD
Base Band Block
CLK and Data Signals etc
Noise Related to LCD is coming from Base Band Block :-Clock and Data Signals
-Noise on Power Line to IC Processing Many Data -Noise Generated by IC Operated at High Frequency
What type of filters
are required?
What kind of solutions are necessary?
Solution Idea with EMI Filter
To Insert EMI Filter in Signal Lines
at the Position mentioned below.
Inserted here.
LCD
RF MMIC
FPCB
Base Band IC
Base Band Area
RF Area Camera
Need to pay attention to Data signal waveform to camera module.
Specification
Arrays LC Combined Type : NFA21SL Series
Chip Ferrite Beads Arrays :BLA2A Series
010
2030405060
1
10
100
100010000
Frequency [MHz]
I n s e r t i o n L o s s [d B ]
(50 ohm - 50
Insertion Loss Curve
NFA21SL207X1A4
NFA21SL307X1A4
Equivalent Circuit
①②
③④⑤⑥
⑦
⑧
G N D
G ND ⑨
⑩
③④⑤⑥：ＩＮ（ＯＵＴ）⑦⑧⑨⑩：ＯＵＴ（ＩＮ）
＊Please change IN/OUT according to the circuit condition.
Photo
(size : 0804)
100
200
300
400
1
101001000
Frequency [MHz]
I m p e d a n c e [o h m ]
BLA2AAG221SN4
BLA2AAG121SN4
Impedance -Frequency Characteristic
(size : 0804)
Verification with Actual Mobile Phone
(Data Lines)
Using NFA21SL307X1A4 on data lines in GSM,
Evaluated the improvement in RF Limit Level (Error Rate > 0%)
Insert EMI Filter
LCD
RF MMIC
FPCB
Base Band IC
Base Band Area
RF Area Camera
Measure Signal & Clock Waveform
Measurement Result
After : NFA21SL307X1A4
Before : No Filter(Short)
-1.0
-0.50.00.51.01.52.02.53.03.5-125
-100-75-50-250255075100125
Time [ns]
V o l t a g e [V ]
-1.0
-0.50.00.51.01.52.02.53.03.5-125
-100-75-50-250255075100125Time [ns]
V o l t a g e [V ]
Waveform
-110
-108-106-104-102-100-98-960
10
20
30
40
50
607080
90100110120
CH [ch]
R F L e v e l [d B m ]
No Filter
NFA21SL307X1A4
Bit Error Rate
Measurement Method
EMC Test in TEM CELL EMC Test in EMC Chamber
1. Internal Interference
2) Decrease in RF Limit Level for Receiving
Decrease in RF Limit Level for Receiving
Mapped Noise Radiation (800M-1GHz) from FPCB with EMI Tester, during
Camera Operation
Mechanism
By Noise From Camera Module
Will be Interfered
RF Signal from
Base Station
10203040506070800
850
900
950
1000
Frequency [ MHz])
N o i s e L e v e l [ d B u V ])
Noise Floor
Mapped at this Freq.
EMC noise problems
from Digital Camera module
?Decrease in RF Limit Level for Receiving
Situation: When the camera function is “ON”, we see big damages
on the RF limit level.
Concern: In feature models, we may also see more serious problem even the camera function is “OFF”….
?Bit error rate problem
Situation: More Base band functions, more serious problems come up.
Concern: Video phone function may cause more serious problem, too.
Any Solutions?
2 Way Noise Conduction would be concerned.
Flexible Circuit Board
IC
Camera
Clock / Control Signals
Data / Control Signals
Connector to main board
What kind of solutions are necessary?What type of filters are required?
EMI Solution idea for Camera Modules
To use :
(1) EMI Filters for Noise from Baseband circuit.
(2) Shielding for Noise from Camera Module
Base Band IC
(1)
LCD
FPCB
(2)