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IC

High-Speed IC Board-level EMI Solution Study

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IC

High-Speed IC Board-level EMI Solution Study

StudentSheng-Wang Hsieh

AdvisorDr. Lin-Kun Wu

A Thesis

Submitted to College of Electrical and Computer Engineering

National Chiao Tung University

in partial Fulfillment of the Requirements

for the Degree of

Master of Science

in

Communication Engineering

March 2009

Hsinchu, Taiwan, Republic of China

http://dpeecs.nctu.edu.tw/professor/p3.html

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IC

F F T

R C

I C

( F A M )

ii

High-Speed IC Board-level EMI Solution Study

StudentSheng-Wang Hsieh

AdvisorsDr. Lin-Kun Wu

Degree Program of Electrical and Computer Engineering

National Chiao Tung University

ABSTRACT

In this thesis, the purpose is to study the mechanism and theory of high

speed print circuit board EMI issue. And then presents a real case of a

dual-mode handset as demonstration for practical EMI solving technique and

procedure,

The main EMI mechanism comes from Ground Bounce and Simultaneous

Switching Noise (SSN). Main factors of EMI are inductance of high frequency

switching current path and length of the path. Reducing the path inductance

(such as by making wider PCB trace) and utilizing high frequency and low

frequency de-coupling capacitor combination can both reduce the EMI strength.

When solving the real case of a dual-mode handset EMI, by investigating

into clock signal frequency domain data from digital scopes FFT output, we can

identify which clock signal contributing EMI output. Having identified the EMI

source, we utilize RC circuit to reduce clock signal strength so as to make EMI

strength lower. For direct EMI emitted from IC, we use flexible absorbing

material (FAM) or conductive shielding as counter measure.

iii

iv

--------------------------------------------------- i

--------------------------------------------------- ii

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--------------------------------------------------- iv

--------------------------------------------------- v

--------------------------------------------------- vi

----------------------------------------------- 1

1.1 --------------------------------- 3

1.2 ------------------------------------- 5

1.3 ----------------------------------- 7

1.4 ------------------------------- 7

1.5 --------------------------------- 8

1.6 ------------------------------- 9

1.7 ----------------------------------- 11

1.8 ------------------------------------- 12

------------------------------------- 15

2.1 EMI-------------------------------- 15

2.2 ----------------------------------------------- 16

2.3 ----------------------------------------------- 28

------------------------------------- 30

3.1 78MHz------------------------------------------ 30

3.2 96MHz------------------------------------------ 34

----------------------------------------------- 44

--------------------------------------------------- 45

v

1.1 CMOS [1]---------------------- 6

1.2 CMOS PCB ----------------- 6

1.3 CMOS [1]-------------------- 7

1.4 CMOS PCB --------------- 7

1.5 RLC ---------------------------- 11 1.6 -------------------------------- 11

1.7 RLC ------------------------ 12 1.8 ---------------------------- 12

1.9 -------------------------------------- 13

1.10 CPU -------------------------------- 14

2.1 EMI 30~300MHz------------------ 15

2.2 EMI 300~1000MHz---------------- 16

2.3 39MHz ----------------------------------- 19

2.4 39MHz --------------------- 20

2.5 39MHz --------------------- 20

2.6 39MHz ------------------------- 21

2.7 39MHz ------------------------- 22

2.8 39MHz FFT --------------------- 22

2.9 39MHz FFT --------------------- 23

2.10 39MHz / FFT -------------- 23

2.11 78MHz ----------------------------------- 24

2.12 78MHz ----------------------------------- 24

2.13 78MHz --------------------- 25

2.14 78MHz --------------------- 25

2.15 78MHz ----------------------------------- 26

2.16 78MHz FFT ------------------------------- 27

2.17 ------------------------------------------ 28

2.18 78MHz RC -------------------------------- 29

3.1 78MHz ------------------------- 30

3.2 78MHz FFT ------------------------- 31

3.3 78MHz FFT --------------- 31

3.4 78MHz EMI 30~300MHz---- 32

3.5 78MHz EMI 300~1000MHz-- 33

3.6 ABSORBER #1 EMI 30~300MHz 35

3.7 ABSORBER #1 EMI 300~1000MHz 36

3.8 CPU shielding 14mm 30~300MHz------- 38

vi

3.9 CPU shielding 14mm 300~1000MHz----- 39

3.10 CPU shielding 30mm 30~300MHz------- 40

3.11 CPU shielding 30mm 300~1000MHz----- 41

3.12 CPU shielding 30~300MHz-------- 42

3.13 CPU shielding 300~1000MHz------ 43

1

CPU

PCB

2

PCB SMT

3

1.1

( )

(Ground Bounce)

L i(t)

V(t)

V(t) = L di(t) / dt (1.1)

-I (Delta-I noise)

Ground Bounce (Simultaneous

Switching Noise, SSN)

( )

4

i(t)

IC IC

1. IC

IC

2.

(Noise Margin) IC

(False Switching)

3. (Voltage Controlled Oscillator VCO)

VCO

VCO

4.

5. (Multi-layer PCB)

5

(Cross-talk)

6. ( ) Patch Antenna

Patch Antenna

IC

1.2

(Power

Plane) ( IC )

(Ground Plane) (Reference

Plane)

6

1.1 CMOS

, PMOS

PMOS

CMOS 1.2

PCB PCB

1.1 CMOS [1]

1.2 CMOS PCB

7

1.3

0

1.3 CMOS [1]

1.4 CMOS PCB

1.4

8

1.3 1.4 CMOS

(Non-ideal Current Return Path)

PMOS

( )

1.5

(Voltage Droop)

9

( )

Zc = 1 / jwC (1.2)

C w

Zc 0

1.6

RLC 1.5 Rs

(Equivalent Series Resistance) L

C

10

Zc (Self Resonant

Frequency) fO

1.6 f O Zc

fO

C f O

L

11

1.5 RLC

1.6

1.7

12

1.7

1.8

1.7 RLC

1.8

13

1.8

GSM+WiFi

block diagram 1.9

1.9

clock source CPU PLL

CPU 1.10

1. CPU 96MHz 14.72MHz 48MHz

2. CPU 32KHz

12MHz13MHz39MHz48MHz78MHz 78MHz

SDRAM 39MHz LCM

14

1.10 CPU

CPU

30MHz 1000MHz

PCB

(Flexible Absorber Material FAM)

15

2.1 EMI

2.1 (30MHz 300MHz)

2.2(300MHz 1000MHz)

2.1 EMI 30~300MHz

16

2.2 EMI 300~1000MHz

2.2

2.2.1 EMI

2.1 30MHz 300MHz

17

78.06Mhz96.96MHz195.24MHz

274.08MHz 232MHz 1.10

CPU CLOCK CPU PLL

EMI CPU CLOCK

CPU CLOCK

78MHz

78.06MHz = 78MHz x 1

232MHz = 78MHz x 3

96MHz

96.96MHz = 96MHz x 1.01

195.2MHz = 96MHz x 2.03 = 96.96MHz x 2.01

39MHz

274.08MHz = 39MHz x 7.03

18

2.2 300MHz 1000MHz

545MHz

312MHz350.4MHz390MHz429MHz468MHz507MHz545MHz

585MHz 623.4MHz 702MHz 781.6MHz 938.4MHz

30MHz 300MHz

CPU CLOCK

312MHz = 78MHz x 4 = 39MHz x 8

350.4MHz = 39MHz x 8.98

390MHz = 78MHz x 5 = 39MHz x 10

429MHz = 39MHz x 11

468MHz = 78MHz x 6 = 39MHz x 12

507MHz = 39MHz x 13

545MHz = 78MHz x 6.99 = 39MHz x 13.97

585MHz = 39MHz x 15

623.4MHz = 78MHz x 7.99 = 39MHz x 15.98

19

702MHz = 78MHz x 9 = 39MHz x 18

938.4MHz = 78MHz x 12.03 = 39MHz x 24.06

39MHz 78MHz 96MHz

2.2.2 39MHz

CPU 39MHz

2.3 39MHz

CPU PCB LCM

2.3

2.4 2.5 2.4 CPU

20

LCM LCM (

) ( ) CPU

CPU CPU 2.5

CPU LCM

LCM ( ) ( ) LCM

CPU CPU

2.4 39MHz

21

2.5 39MHz

39MHz 2.6

RING 2.7

39MHz 39MHz

FFT 39MHz 2.8

2.9 2.8

2.8 2.9 2.10

2.6 39MHz

22

2.7 39MHz

2.8 39MHz FFT

23

2.9 39MHz FFT

2.10 39MHz / FFT

24

2.2.3 78MHz

CPU 78MHz

2.11 78MHz

2.12 78MHz

CPU 78MHz LC

SDRAM PCB LC

CPU 78MHz

78MHz

2.13

2.14 2.13 CPU

25

SDRAM SDRAM ( )

( ) CPU CPU

CPU 2.14

CPU

SDRAM SDRAM ( ) ( )

SDRAM CPU

CPU

2.13 78MHz

2.14 78MHz

26

78MHz 2.15

RING

FFT 78MHz 2.16

2.15 78MHz

27

2.16 78MHz FFT

2.2.4 96MHz

CPU 96MHz CLOCK CPU

CPU CPU

EMI

28

2.3

2.3.1 96MHz

96MHz CPU

1. absorber( ) CPU

2. CPU

CPU 25mmx25mm absorber

30mmx30mm 12mmx12mm

30mmx30mm PCB ( )( 2.17)

2.17

2.3.2 78MHz

2.15 RING

29

LC RC

SDRAM 2.18

2.18 78MHz RC

2.3.3 39MHz

39MHz

30

3.1 78MHz

78MHz 3.1

2.15 78MHz RING

FFT 3.2

2.16 78MHz

2.16 3.2 3.3

3.1 78MHz

31

3.2 78MHz FFT

3.3 78MHz FFT

EMI 3.4 3.5

2.1 2.2 232MHz312MHz390MHz468MHz

545MHz623.4MHz702MHz 938.4MHz

32

3.4 78MHz EMI 30~300MHz

33

3.5 78MHz EMI 300~1000MHz

34

3.2 96MHz

3.2.1 absorber

3.6 3.7 3.4 3.5

195MHz 38.91

dBuv 31dBuv 7.9dBuv 96MHz

CPU absorber

35

3.6 ABSORBER #1 EMI 30~300MHz

36

3.7 ABSORBER #1 EMI 300~1000MHz

3.2.2

14mmx14mm CPU 3.8 3.9

3.4 3.5 195MHz

38.91dBuv 39.3dBuv

37

30mmx30mm CPU 3.10

3.11 3.4 3.5

195MHz 38.91dBuv 42.2dBuv

30mm PCB (

) 3.12 3.13 3.4

3.5 195MHz 38.91dBuv

36.1dBuv 2.8dBuv

1. Absorber

2.

38

3.8 CPU shielding 14mm 30~300MHz

39

3.9 CPU shielding 14mm 300~1000MHz

40

3.10 CPU shielding 30mm 30~300MHz

41

3.11 CPU shielding 30mm 300~1000MHz

42

3.12 CPU shielding 30~300MHz

43

3.13 CPU shielding 300~1000MHz

44

(PCB)

(Ground Bounce) (SSN)

FFT

LC RC IC

(FAM)

45

1. S H. Hall,G. W. Hall and J. A. Mccall, High-Speed Digital

System Design, A Handbook of Interconnect Theory and

Design Practices. 2.

2. Howward W. Johnson and Martin Graham, High-Speed Digital

Design, A Handbook of Block Magic. Prentice Hall, 1993 .

3. 4/6

2005

4. IC

2006

5. A Wireless VoIP Processor Implementing the 802.11

Standard AT76C902 Preliminary, Atmel.

6. 802.11a/b/g Baseband Controller AT76C517, Atmel.

7. (FAM)