Basic Interconnects at High Frequencies (Part 1)

Transcription

1 Basic Intcnncts at High Fquncis (Pat ) Outlin Tw-wi cabls and caxial cabls Stiplin Stiplin gmty and fild distibutin Chaactizing stiplins Micstip lin Micstip gmty and fild distibutin Chaactizing micstip lins Embddd micstips Lsss in stiplins and micstip lins 2

2 Tw-Wi Lins Unsuitabl f high-fquncy applicatins Thy hav high adiatin lsss (lag EMI) (R. Ludwig and P. Btchk, RF Cicuit Dsign, Pntic Hall, 2) 3 2-Wi Lin Tansmissin Lin Paamts μ csh D L π 2a π' C csh ( D / 2a) Rs R (Ω/m) aπ πω'' G csh ( D / 2a) (H/m) (F/m) (S/m) wh R s sufac sistivity σδ s δ s skin dpth πfσμ ' j '' '( j tanδ ) ' μ 4π μ μ 2 μ (F/m) (H/m) (D. M. Pza, Micwav Engining, Wily, 25) 4 2

3 Tw-Wi Lin (Nglcting Lsss) μ csh D L π 2a (H/m) π' C csh ( D / 2a) (F/m) csh π D 2a μ ' (Ω) csh D π 2a (Ω) 5 Tw-Wi Lin Pactical Issus Th mst cmmn 2-wi TL is th twin-lad lin Typical f twin-lad lins: 75Ω, 3Ω, and 4Ω Thy us cpp f th wis, spaatd by a plastic (typically plythyln) ibbn 3-Ω twin-lin 4-Ω ladd twin-lin 3Ω t 75Ω balun (K. L. Kais, Tansmissin Lin Matching and Csstalk, CRC, 25) 6 3

4 Caxial Cabls Typical caxial cabls a usd up t GHz (high-nd caxial lins can b usd up t 8 GHz) Thy hav n adiatin lsss (ut cnduct is gundd) Typical dilctics: Plystyn ( 2.5, tanγ.3 * γ ) Plythyln ( 2.3, tanγ.4 * ) Tfln ( 2., tanγ.4 * ) * at GHz (R. Ludwig and P. Btchk, RF Cicuit Dsign, Pntic Hall, 2) 7 Caxial Cabls Tansmissin Lin Paamts μ b L ln 2π a (H/m) 2π' C ln( b / a) (F/m) R s R + 2π a b (Ω/m) 2πω '' G ln( b / a) (S/m) wh R s sufac sistivity σδ s δ s skin dpth πfσμ ' j '' '( j tan δ ) ' μ μ μ (F/m) 7 μ 4π (H/m) (D. M. Pza, Micwav Engining, Wily, 25) 8 4

5 Caxial Cabls Tansmissin Lin Paamts μ b 2π' L ln (H/m) C ( F/m) 2π a ln( b / a) L (nh/m) Distibutd Paamts f a Caxial Cabl b/a C (pf/m) Distibutd Paamts f a Caxial Cabl b/a 9 Caxial Cabls (Nglcting Lsss) μ b L ln 2π a 2π' C ln( b / a) (H/m) (F/m) ln b 2π a μ ' (Ω) ln b 2π a (Ω) 5

6 Caxial Cabls (Nglcting Lsss) ln b 2π a μ ' (Ω) (hms) b/a Caxial Lin Pactical Issus Typical f caxial lins: 5Ω, 75Ω and 93Ω Th mst cmmn typ is th RG-6 cabl (TV, 75Ω) Dtaild tchnical data-shts a availabl f ach typ RG-59 Cnncts ( 29) 2 6

7 Stiplins A stiplin tac is immsd in a dilctic and sandwichd btwn tw mtallic plans Th lctic and magntic filds a cnfind t th dilctic (TEM ppagatin if lsss a small) 3 TEM Ppagatin Th lctic and magntic filds in th dictin f ppagatin a z (R. Ludwig and P. Btchk, RF Cicuit Dsign, Pntic Hall, 2) 4 7

8 Stiplin Gmty and Fild Distibutin v c c 3Mm/s p (D. M. Pza, Micwav Engining, Wily, 25) 5 Chaactizing Stiplins ( Thicknss) 3π ( W b +.44b) wh W is th ffctiv width givn by W b W b W (.35 ) b 2 f f W b W b (D. M. Pza, Micwav Engining, Wily, 25) 6 8

9 Chaactizing Stiplins (Nn Thicknss) (S. C. Thiauf, High-Spd Cicuit Bad Signal Intgity, Atch, 24) 7 Chaactizing Stiplins (Nn Thicknss) 94.5 w f.35 w C f b t k + b wh k t b and C f is th finging i capacitanc givn by C f k 2 π [ 2k ln( k + ) ( k )ln( ) ] (pf/m) (S. C. Thiauf, High-Spd Cicuit Bad Signal Intgity, Atch, 24) 8 9

10 Chaactizing Stiplins (Nn Thicknss) wh 6 4 ln b πd f w <.35 b t d w t 4πw t + + ln +.5π 2 πw t w 2 (S. C. Thiauf, High-Spd Cicuit Bad Signal Intgity, Atch, 24) 9 Chaactizing Stiplins (Nn Thicknss) (S. C. Thiauf, High-Spd Cicuit Bad Signal Intgity, Atch, 24) 2

11 Micstips A micstip tac is sandwichd btwn tw vy diffnt dilctics Du t this nn-hmgnus mdia, micstips ppagat in nn TEM md Using th ffctiv dilctic cnstant appach, micstips can b mdld as if thy had an hmgnus mdia (quasi TEM ppagatin if th lsss a small) 2 Micstip Gmty and Fild Distibutin Substats with high duc fild lakag and css cupling Substats with small duc dilctic lsss (R. Ludwig and P. Btchk, RF Cicuit Dsign, Pntic Hall, 2) 22

12 Micstip Gmty (cnt) Expsd micstip: Embddd micstip: sld mask (S. C. Thiauf, High-Spd Cicuit Bad Signal Intgity, Atch, 24) 23 Chaactizing Expsd Micstip Lins v p c c 3Mm/s (h / w) (R. Ludwig and P. Btchk, RF Cicuit Dsign, Pntic Hall, 2) 24 2

13 Chaactizing Expsd Micstip Lins (cnt) nglcting thicknss (t ) Mdl : Walk s fmula if w, h 6 8 ln h w + w 4h w 2π if >, 6 h w h h h w w Ω Ω (C.S. Walk, Capacitanc, Inductanc and Csstalk Analysis; Atch, 99) 25 Chaactizing Expsd Micstip Lins (cnt) Mdl 2: Gupta s fmula if w, h 6 8 ln h w + w 4h Ω if w >, h 2π w h ln w h Ω (K.C. Gupta t. al, Cmput-Aidd Dsign f Micwav Cicuits; Atch, 98) 26 3

14 Chaactizing Expsd Micstip Lins (cnt) 4 35 Chaactistic Impdanc f a Micstip Lin Gupta Walk 3 25 (hms) w/h 27 Chaactizing Expsd Micstip Lins (cnt) Effcts f t n (R. Ludwig and P. Btchk, RF Cicuit Dsign, Pntic Hall, 2) 28 4

15 Chaactizing Expsd Micstip Lins (cnt) cnsiding thicknss (t ) if w > 2, h if w 2, h ln h.8w + t 2π w ln w h h Ω Ω (S. C. Thiauf, High-Spd Cicuit Bad Signal Intgity, Atch, 24) 29 5-Ω Stiplin and 5-Ω Embddd Micstip w 5mil t.65mil h 6.mil w 5mil t.65mil (S. C. Thiauf, High-Spd Cicuit Bad Signal Intgity, Atch, 24) 3 5

16 Lsss in Tansmissin Lins Th ttal lss α t is th sum f th cnduct and dilctic lsss α α α + α Cnduct lsss α c a du t th sistiv lsss in th signal tac and th tun path (pducd by a cnductiv cunt) Dilctic lsss α d a du t th ngy lst in th dilctic lays (pducd by a displacmnt cunt) t c d 3 5-Ω Stiplin and 5-Ω Embddd Micstip (S. C. Thiauf, High-Spd Cicuit Bad Signal Intgity, Atch, 24) 32 6