2010/10/31

1

A Novel Embedded Common-mode Filter for above GHz differential signals based

on Metamaterial concept

Tzong-Lin WuProfessorProfessor

Graduate Institute of Communication Engineering, National Taiwan University, Taipei, Taiwan.

OutlineIntroductionProblems and conventional solution

c

Proposed solution and concept• DGS• Metamaterial Transmission line

Case study：component• RFI• EMI

C l iConclusion

2

2010/10/31

2

Trend of Differential Signaling

14

16 2.0

1.8

6

8

10

12

14

Dat

a R

ate

(Gb/

s)

GDDR 5

USB 3 0

SATA III

SATA IV

1.8

1.6

1.4

1.2

1.0

0.8

Giga EthernetPCI-E IV

DC

Level (V

)

SPMT

0

2

4

2008 2010 2012 2014 2016 2018 2020Year

USB 3.0

HDMI 1.3DDR 4

Display Port

0.8

0.6

0.4

EMI / RFI Trend

7

8New RFI Band

3

4

5

6

7

Freq

uenc

y (G

Hz)

LTE,

1 ~ 5 GHz with 6 dB lower limit

New EMI Band

RFI Band

WLAN 5.4 GHz

UWB 3.1 ~ 10.6 GHz

CISPR CLASS B

40

60

80

(dBμv

/m)

6 dB

Clock Rate  & Clock Rate  & Noise BandNoise Band

0

1

2

2008 2010 2012 2014 2016 2018 2020

F

Year

WLAN, Bluetooth,3G Mobile,GPS,GSM,DTV

30 MHz ~1 GHz

EMI Band0

20

1 2 3 4 5

Lev

el (

Frequency (GHz)

2010/10/31

3

Electronic SystemSATA III,USB 3.0 I/O

Common Mode Noise3D IC

Display Port,HDMI I/O

VRM

Patterned Ground

RF Chip

Diff. Pair

Analog

Processor/Memory

MEMS

EMI

5

55ntu     EMC  Group

EMI

Simultaneous Switching Noise

Common Mode Noise

Bend

Crosstalk

τr ≠ τf CM Noise

6

V1

V2L+ΔL

L

Length MismatchLayout Requirement

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4

ExampleA 3.5 Gbps differential PRBS passing through a differential pair

with length mismatch (PRBS：Pseudorandom Binary Sequence)

0.1

0.2

0.3

de (V

)

0.010

0.015

ude

Time Domain Frequency Domain

V1

V2L+ΔL

L

7

1 2 3 4 5 6 70 8

-0.2

-0.1

0.0

-0.3

time (ns)

Ampl

itu

3 6 9 120 15

0.005

0.000

Frequency (GHz)

Ampl

it

ProblemsSI - Mode Conversion：Common mode to Differential mode.

Common mode noise

EMI - Attached I/O cables (HDMI, SATA III, USB 3.0…) .

Asymmetrical structure

Zo Zo

8

, )

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5

ProblemsPI - Via transition, crossing slots (plate cavity).

RFI - Shielding metals, heat sink, daughter boards (Dipole).

Daughter

9

Vs

Mother Board

Conventional Solution

I1

CM mode I1 = I2 = Ic

L+MIc

I2

L+MIc

DM mode I1 = I2 = Id

L-M

L-M

Id

‐ Id

Ferrite： Thin Film：

Parasitic Cap.

10

2010/10/31

6

BottleneckL-M

L-M

Id

‐ Id

Parasitic Cap.Asymmetrical geometry

L ≠ M, parasitic C, and asymmetrical geometryd d

L M‐ Id

11

degrade the differential signal quality.

Proposed embedded structures1. Defected Ground Structure (DGS)

2. Transmission Line Metamaterial

h

12

2010/10/31

7

Defectd Ground Structure(DGS)Common Mode Excite (Noise)Differential Mode Excite (Signal)

13

DGS-1

0.47 λg × 0.76 λg

14

[1] W. T. Liu, C. H. Tsai, T. W. Han, T. L. Wu, “An embedded common mode suppression filter for GHz differential signals Using Periodic Defected Ground Plane”, IEEE Microwave and Wireless Components Letters, vol. 18, no4, pp. 248-250, Apr, 2008.

Use Periodic DGS to produce electromagnetic bandgap for common mode

2010/10/31

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Performance

-10

0

70

-60

-50

-40

-30

-20

Scc31

S31

(dB

)

Sdd31

S dc21

3.5~5.5 GHz

aram

eter

15

2 3 4 5 6 7 8-90

-80

-70

Frequency (GHz)

HFSS Measurement Equivalent Model

S p

DGS-2

0.44 λg × 0.44 λg

16

Apply mutual coupling to enhance the bandwidth of common mode suppression.

[2] S. J. Wu, C. H, Tsai, and T. L. Wu “A novel wideband common-mode suppression filter for GHz differential signals using coupled patterned ground structure,” IEEE Trans. Microwave Theory Tech., vol. 57, no.4, pp. 848-855, Apr. 2009.

2010/10/31

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Design Concept (1/3)

0

0

0 2 4 6 8 10Frequency [GHz]

-50

-40

-30

-20

-10

Scc2

1 [d

B]

Equivalent circuit modelHFSS

• LDGS1=2.36nH, CDGS1=0.324pF.

170 2 4 6 8 10

Frequency [GHz]

-50

-40

-30

-20

-10

Scc2

1 [d

B]

Equivalent circuit modelHFSS

• LDGS3=3.39nH, CDGS3=0.276pF.

Design Concept (2/3)Magnetic Coupling Coefficient

0 2 4 6 8 10-50

-40

-30

-20

-10

0

Scc2

1 [d

B]

Equivalent circuit modelHFSS

18

11.0

22

22

=+−

==

m

me

memm

kffff

LLk

0 2 4 6 8 10Frequency [GHz]

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10

Asynchronous Tuned Magnetic Coupling

0

10

0

0 2 4 6 8 10Frequency [GHz]

-40

-30

-20

-10

Scc2

1 [d

B]

PECPMC

19

043.0

22

22

22

22

21

21

21

21

±=

⎟⎟⎠

⎞⎜⎜⎝

⎛

+−

⎟⎟⎠

⎞⎜⎜⎝

⎛

+−

=

M

em

me

em

meM

k

ffff

ffffk

0 2 4 6 8 10Frequency [GHz]

-60

-50

-40

-30

-20

-10

Scc2

1 [d

B]

Equivalent circuit modelHFSS

Performance

|Scc||Sdd|

| cc|

20

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Design Concept-TL MetamaterialPECElectric Field Line of the Differential Mode

(a) (b)

(c) (d)

PECPEC

21

(c) (d)

ws

d

p

l

p

hk

Type1：PCB/SiP Type2：Component

New Equivalent circuit

1L ′mL ′′mL

′0L

′0L′mC

1L ′1

mC'

1C' 1C'

m

′0C′

0C

Conventional

22

2L ′2C'

New

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12

New Equivalent circuit

′mL ′ L - L′ ′

PECPECPMC

1L ′1L ′

L ′

mC'

1C' 1C'

C'

2 m1C C′ ′+

m1L L

Odd Mode

C′m1L L+′ ′

PMC

2C C′ ′+

m1L - L′ ′

1C′m1L L+′ ′

2 L ′2C'

23

2L2C1C′

22 L ′22C'

Even Mode

2 m1C C+

Odd Mode

22 L22C

Even Mode

Metamaterial Differential LineAssume p << λ

1γ = α + jβ = Z Y

and lossless

m1L L+

0< < c

c 02

e e e

2 21

1 m 2 2

c

22 21

γ = α + jβ = Z Yp

C (1 - ω )jω = (L + L )p (1 - ω )

= α , ω ω ω

ωω

1 1ω = , ω =L CL (2 +

C )C

0

p

Ze

24

1C1

22L22C < 0

Effective material parameter :2 2

12 2e

c

C (1 - ω )ε(ω) = Y jω = ,

(1 - ω )ω

ω0

0 < < cω ω ωEven Mode

Ye

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Dispersion Diagram

30

10

20

30

40

50

60

Freq

uenc

y (G

Hz)

two-port circuit modeldistributed circuit

5

10

15

20

25

30

Freq

uenc

y (G

Hz) two-port circuit model

distributed circuit

10 ~ 13.6 GHz

25

0 20 40 60 80 100 120 140 160 180βp (degree)

00 20 40 60 80 100 120 140 160 180

βp (degree)

0

Example I: Embedded CMF in LTCC

w1 = 0.1 mms1 = 1.38 mm

2 18

h1h2

s3 ws1s2 = 2.18 mms3 = 0.58 mmw = 3.2 mmh1 = 0.115 mmh2 = 0.468 mmh3 = 0.312 mmg = 0.18 mmp = 1.28 mm

Top view

h3

s2

26

pgSide view

DK=7.8 4 Cells

Size：0.3 λg × 0.2 λg

c

2

0

2

12

2

1ω =(2 + C )

1ω =C

L

L

C

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Performance

0

150

200

0 1 2 3 4 5 6 7 8 9 10-50

-40

-30

-20

-10

S-pa

ram

eter

(dB

)

Sdd21_simu.Scc21_simu.Scc21_circuit_model

0 1 2 3 4 5 6 7 8 9 10-200

-150

-100

-50

0

50

100

150

phas

e (d

eg)

ang(Sdd21)

27

A designed stop-band (3.8-7.1 GHz) for common mode is seen both in simulation and measurement

Frequency (GHz) Frequency (GHz)

Example II: wideband CMF

Low Temperature Co-fired Ceramic (LTCC)：# of Layer：11 (Ag)DK = 3.9# of Cell：5Size --- 0.05 λg × 0.26 λg (1.6 x 8 mm2)

28

Size 0.05 λg × 0.26 λg (1.6 x 8 mm )

Photograph

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15

Performance-Diff.

0 200

Amplitude Phase

-40

-35

-30

-25

-20

-15

-10

-5

S pa

ram

eter

(dB

)

Sdd21_Sim.Sdd21_Meas.Sdd11_Sim.Sdd11_Meas. -150

-100

-50

0

50

100

150

Phas

e (D

egre

e)

Phase(Sdd21)_Sim.Phase(Sdd21)_Mesu.

29

1 2 3 4 5 6 7 8 9 10Frequency (GHz)

-451 2 3 4 5 6 7 8 9 10

Frequency (GHz)

-200

A good differential mode transmission is seen both in simulation and measurement

Performance-CM

-10

0

3 1 8 9 GHz

-60

-50

-40

-30

-20

S pa

ram

eter

(dB

)

Scc21_Sim.Scc21_Meas.Scd21_Sim.Sdc21 Meas.

3.1 ~ 8.9 GHzFBW = 103 %

30

1 2 3 4 5 6 7 8 9 10Frequency (GHz)

-80

-70

Sdc21_Meas.

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Example III: Compact CMFLow Temperature Co-fired Ceramic (LTCC)：# of Layer：17 (Ag)DK = 7.8

1 3

Goal：Size ---0606 (60 mil X 60 mil)Case 1 --- 2.5 ~ 8 GHz

60 mil60 mil

PCB

2 4

Performance

-5

0

35

-30

-25

-20

-15

-10

5

S pa

ram

eter

s (d

B)

Sdd21_simuScc21 simu

2.2 ~6.5 GHz

32

0 1 2 3 4 5 6 7 8 9 10Frequency (GHz)

-45

-40

-35 _Scc21_measSdd21_measSdc21_meas

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Example IV: CMF for EMI/RFI Suppression

Low Temperature Co-fired Ceramic (LTCC)：# of Layer：17 (Ag)DK = 7 8

L1 0.86 nH

L2 2.02 nH

L 0 05 H

1 3

DK = 7.8

Goal：Frequency---@ 2.1 G for UMTSSize ---0606 (60 mil X 60 mil)

Lm 0.05 nH

C1 1.5 pF

Cm 0.07 pF

0

2 1

1 2 .1 G H zL C

ω = =

33

PCB

2 41.6 mm 1.6 mm

RFI for 3G UMTS

UMTS：Universal Mobile Telecommunications System is one of the third-generation (3G) mobile telecommunication technologies.

Frequency band Frequency (MHz) Region2100 1920-1980, 2110-2170 Europe, Asia, Oceania, Brazil1900 1850-1910, 1930-1900 North America , Latin America1700 1710-1755, 2110-2155 USA, Canada

O

34

900 880-915, 925-960 Europe, Asia, Oceania 850 824-849, 869-894 USA800 830-840, 875-885 Japan

[1] http://www.umtsworld.com/technology/frequencies.htm

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S parameter

0 180

PhaseMagnitude

-25

-20

-15

-10

-5

S pa

ram

eter

(dB

)

Sdd21 -- simulationScc21 -- simulationSdd21 -- measurement Scc21 -- measurement Sdd21 -- equivalent model

1.7~2.6 GHz

-120

-60

0

60

120

Phas

e (D

egre

e)

ang(Sdd21) -- measurementang(Sdd21) -- simulation

35

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Frequency (GHz)

-30

Sdd21 equivalent modelScc21 -- equivalent model

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Frequency (GHz)

-180

RFI-Measurement setupFrequency @ 2.1 GHz UMTSInput Power ：-30 dBmW

Antenna

RF Board

GND

via

TEST SAMPLE

connector

36

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RFI-Performance

Without CM filter With CM filter

Ampl

itude

(dBm

)

Ampl

itude

(dBm

)

37

Frequency (MHz) Frequency (MHz)

EMI-Measurement setupBottom

Top

38

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20

EMI-Performance

40

50

CM current rejection

‐20

‐10

0

10

20

30

CM

Cur

rent

[dB

uA]

w/o CMFw/ CMF

1.7~2.6GHz

39

‐30

0 0.5 1 1.5 2 2.5 3 3.5

Frequency[GHz]

About 6-8 dB suppression for CM current is observed from 1.7 GHz to 2.6 GHz

ConclusionDGSs and Metamaterial concept are proposed to design the embedded common-mode filterdesign the embedded common-mode filter.

Good diff. mode transmission with low mode conversion.

Wid b d d iWideband common mode suppression.

Realized on PCB and LTCC substrate (SiP).

40

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41