A Novel Embedded Common-mode Filter for above GHz differential signals based on Metamaterial concept. Tzong-Lin Wu

Transcription

1 c //3 A Novel Embedded Common-mode Filter for above GHz differential signals based on Metamaterial concept Tzong-Lin Wu Professor Graduate Institute of Communication Engineering, National Taiwan University, Taipei, Taiwan. Introduction Outline Problems and conventional solution Proposed solution and concept DGS Metamaterial Transmission line Case study:component RFI EMI Conclusion

2 //3 Trend of Differential Signaling 6. Data Rate (Gb/s) GDDR 5 SATA III USB 3. HDMI.3 Display Port SATA IV DDR 4 SPMT Giga Ethernet PCI-E IV DC Level (V) Year EMI / RFI Trend 8 7 New RFI Band WLAN 5.4 GHz EMI Band 3 MHz ~ GHz Clock Rate & Noise Band RFI Band LTE, WLAN, Bluetooth, 3G Mobile, GPS,GSM, DTV New EMI Band ~ 5 GHz with 6 db lower limit (dbμv/m) Level ( db CISPR CLASS B UWB 3. ~.6 GHz Year 3 4 5

3 //3 Electronic System Common Mode Noise 3D IC SATA III, USB 3. I/O VRM Processor /Memory RF Chip Diff. Pair Patterned Ground Display Port, HDMI I/O Analog MEMS EMI ntu EMC Group 5 5 Simultaneous Switching Noise 5 Common Mode Noise Crosstalk τr τf CM Noise Bend L L+ΔL V V Layout Requirement Length Mismatch 6 3

4 //3 Example A 3.5 Gbps differential PRBS passing through a differential pair with length mismatch (PRBS:Pseudorandom Binary Sequence) L L+ΔL V V de (V) Amplitu Time Domain time (ns) ude Amplit Frequency Domain Problems SI - Mode Conversion:Common mode to Differential mode. Common mode noise Zo Asymmetrical structure Zo EMI - Attached I/O cables (HDMI, SATA III, USB 3. ). 8 4

5 //3 PI - Via transition, crossing slots (plate cavity). Problems RFI - Shielding metals, heat sink, daughter boards (Dipole). Daughter Vs Mother Board 9 Conventional Solution I I Ferrite: Thin Film: CM mode DM mode I = I = Ic Ic Ic I = I = Id Id Id L+M L+M Parasitic Cap. L-M L-M 5

6 //3 Id Id Bottleneck Parasitic Cap. Asymmetrical geometry L-M L-M L M, parasitic C, and asymmetrical geometry degraded the differential signal quality. Proposed embedded structures. Defected Ground Structure (DGS). Transmission Line Metamaterial h 6

7 //3 Defectd Ground Structure(DGS) Common Differential Mode Mode Excite (Noise) (Signal) 3 DGS-.47 λg.76 λg Use Periodic DGS to produce electromagnetic bandgap for common mode [] 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. 8, no4, pp. 48-5, Apr,

8 //3 Performance S cc3 S dd3 3.5~5.5 GHz arameter S 3 (db) S p S dc -7 HFSS -8 Measurement Equivalent Model DGS-.44 λg.44 λg Apply mutual coupling to enhance the bandwidth of common mode suppression. [] 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 , Apr

9 Scc [db] Scc [db] Scc [db] //3 Design Concept (/3) Equivalent circuit model HFSS L DGS =.36nH, C DGS =.34pF Frequency [GHz] Equivalent circuit model HFSS L DGS3 =3.39nH, C DGS3 =.76pF Frequency [GHz] Design Concept (/3) Magnetic Coupling Coefficient Equivalent circuit model HFSS k k m m Lm = = L =. f f e e + f f m m Frequency [GHz] 8 9

10 Scc [db] Scc [db] //3 Asynchronous Tuned Magnetic Coupling PEC PMC Frequency [GHz] - k k M M f e f = fm + f = ±.43 m e f e m f + fm fe Equivalent circuit model HFSS Frequency [GHz] Performance S cc S dd

11 //3 Design Concept-TL Metamaterial Electric Field Line of the Differential Mode PEC (a) PEC (b) PEC (c) (d) Type:PCB/SiP Type:Component s w d l h p k p New Equivalent circuit C L C m L m L C L C' m L m L Conventional C' C' C' L New

12 //3 L New Equivalent circuit PEC PMC C' m PEC L m L - L m L C' C' C' C' L L L + L L -LC m PMC m C + C + C L m C' C m Odd Mode L + L m C L Even Odd Mode Even Mode 3 Metamaterial Differential Line Assume p<<λ and lossless γ e = α +jβ = Ze Ye p jω C(-ω ω ) = (L + L ) p ( - ω ) = α, ω < ω < ω c m ωc ω c =, ω = L( +C ) LC C Ze L + L m p Effective material parameter : C(-ω ω ) ε(ω) =Ye jω = <, ( - ω ω ) c ωc < ω < ω Ye C C L Even Mode 4

13 //3 Dispersion Diagram two-port circuit model distributed circuit 3 two-port circuit model distributed circuit 5 ~ 3.6 GHz βp (degree) βp (degree) 5 Example I: Embedded CMF in LTCC s s Top view s3 g p Side view w h h h3 DK=7.8 4 Cells Size:.3 λg. λg w =. mm s =.38 mm s =.8 mm s3 =.58 mm w = 3. mm h =.5 mm h =.468 mm h3 =.3 mm g =.8 mm p =.8 mm ω = c ω = ( C + C ) L L C 6 3

14 S-parameter (db) phase (deg) //3 Performance Sdd_simu. Scc_simu. Scc_circuit_model ang(sdd) A designed stop-band ( GHz) for common mode is seen both in simulation and measurement 7 Example II: wideband CMF Low Temperature Co-fired Ceramic (LTCC): # of Layer: (Ag) DK = 3.9 # of Cell:5 Size λg.6 λg (.6 x 8 mm ) Photograph 8 4

15 S parameter (db) Phase (Degree) //3 Performance-Diff. Amplitude Phase Sdd_Sim. - Sdd_Meas. Sdd_Sim. Sdd_Meas. -5 Phase(Sdd)_Sim. Phase(Sdd)_Mesu A good differential mode transmission is seen both in simulation and measurement 9 Performance-CM S parameter (db) ~ 89GHz 8.9 FBW = 3 % Scc_Sim. Scc_Meas. Scd_Sim. Sdc_Meas

16 S parameters (db) //3 Example III: Compact CMF Low Temperature Co-fired Ceramic (LTCC): # of Layer:7 (Ag) DK = 7.8 Goal: Size (6 mil X 6 mil) Case ~ 8 GHz 3 6 mil 6 mil PCB 4 Performance ~6.5 GHz Sdd_simu -35 Scc_ simu Scc_meas -4 Sdd_meas Sdc_meas

17 //3 Example IV: CMF for EMI/RFI Suppression Low Temperature Co-fired Ceramic (LTCC): # of Layer:7 (Ag) DK = 7.8 Goal: Frequency---@. G for UMTS Size (6 mil X 6 mil) L L.86 nh. nh L 5.5 nh L m C C m.5 pf.7 pf ω = =. G H z LC 3 PCB.6 mm.6 mm 4 33 RFI for 3G UMTS UMTS:Universal Mobile Telecommunications System is one of the third-generation (3G) mobile telecommunication technologies. Frequency band Frequency (MHz) Region 9-98, -7 Europe, Asia, Oceania, Brazil , 93-9 North America, Latin America , -55 USA, Canada , Europe, Asia, Oceania , USA , Japan []

18 S parameter (db ) Phase (Degree) //3 S parameter Magnitude Phase ~.6 GHz 6 ang(sdd) -- measurement ang(sdd) -- simulation -5 Sdd -- simulation - Scc -- simulation Sdd -- measurement Scc -- measurement -5 Sdd -- equivalent model Scc -- equivalent model RFI-Measurement setup GHz UMTS Input Power :-3 dbmw Antenna RF Board GND connector TEST SAMPLE via 36 8

19 //3 RFI-Performance Amplitude (dbm) Without CM filter Amplitude (dbm) With CM filter Frequency (MHz) Frequency (MHz) 37 Bottom EMI-Measurement setup Top 38 9

20 //3 EMI-Performance 5 CM current rejection 4 CM Current [dbua] 3 w/o CMF w/ CMF.7~.6 GHz Frequency[GHz] About 6-8 db suppression for CM current is observed from.7 GHz to.6 GHz 39 Conclusion DGSs and Metamaterial concept are proposed to design the embedded common-mode filter. Good diff. mode transmission with low mode conversion. Wideband b d common mode suppression. Realized on PCB and LTCC substrate (SiP). 4

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