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传输线 巴伦
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2 m R6 A; U6 c* Y U) E) b1.基本原型:: Y ?: V) B5 q7 N0 @
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2.最佳传输条件:
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2.2 传输线长度l应尽可能地小,工程设计中一般取<λ/8
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/ d& T, n& E- } Y D; o; g% ]3.相关公式: N) O1 ^2 D9 i; x0 g
3.1传输损耗公式:2 H6 l: _6 O3 n4 K( @# ^
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% r9 s4 I0 G) ~* P- M! T$ Y3.2反射损耗公式为: / D" ?, X& x4 r- y/ R1 ?
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$ `; ^# Z. q6 Z3 w式中。Rg为源阻抗。L0为空芯绕组电感,μ’为磁导率实部, μ”为磁导率虚部。磁损耗角正切tanδm=μ”/μ’。选择μ’高、tanδm大的材料能够 同时满足传输损耗、反射损耗的指标要求。
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3.3磁导率
V3 u& ]% z* c( X( ^铁氧体磁芯磁导率随频率变化的影响:
, [* H! U$ P6 L3 B- n. @, F磁导率随频率 变化的公式为
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+ S& u, j2 J( @$ C6 i5 w3 a* N: K) Y式中,S为斯诺克常数,,fr为截止频率。
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4 ^" l# C# u+ \" x将上式代人传输损耗公式进行分析得知应选择截止频率低、斯诺克常数高的磁芯材料。
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) k0 G$ L2 ^% p- ]* e. d. {. k综上所述,可以得出磁芯材料的选取原则是要求低频初始磁导率μ’高、截止频率fr低、斯诺克常数S 高、损耗大tanδm的材料。
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4.ADS 中低端巴伦模型
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BALUN1 (Balanced-to-Unbalanced Transformer (Ferrite Core))
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Range of Usage $ a* r8 M+ D6 Y h. X# n! J
Z > 0, Len > 0, AL > 0
1 T _' ^- w9 N3 z# yK ≥ 1) K* v' E3 H2 p
A ≥ 0. J j3 Q4 \; O* }0 T0 v
F ≥ 0- U, a* ^& B; j0 N; B/ {
N ≥ 1
. J A/ v7 x# e& Y$ H$ s- Q/ ^* AParameters , r; C: i) J8 T2 Y+ c. Z+ q0 O |
Name | Description | Units | Default | Z | Characteristic impedance of transmission line | Ohm | 50.0 | Len | Physical length of transmission line | mil | 12.0 | K | Effective dielectric constant(有效介电常数) | None | 2.0 | A | Attenuation (per unit length) of transmission line | dB/meter | 0.0 | F | Frequency for scaling attenuation | GHz | 1.0 | N | Number of turns | None | 5.0 | AL | Inductance index(电感指数) | nH | 960.0 | TanD | Dielectric loss tangent (介质损耗角正切) | None | 0 | Mur | Relative permeability (相对磁导率) | None | 1 | TanM | Magnetic loss tangent(磁损耗正切) | None | 0 | Sigma | Dielectric conductivity (介电导电率) | None | 0 | Temp | Physical temperature | °C | None | ) ^+ I y Y; c
· This component is a length of transmission line(specified by Z, Len, K, A and F) coiled around a ferrite core. x) m" E# }9 E3 ]9 r" j9 W
Choking inductance Lc accountsfor low-frequency roll-off and is given by
; F1 Y# ]3 C1 ^ PLc = N2 × AL5 x$ k6 a- E& u0 H# A
A(f) = A (for F = 0)+ N% L# _ A1 X) Z" G
A(f) = A(F) × file:///C:/Users/wanghai/AppData/Local/Temp/msohtmlclip1/01/clip_image013.png, d; H1 L- U; j$ g
(for F ≠ 0)
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f = simulation frequency: H- t6 f- k s3 Y4 c
F = reference frequency for attenuation ( N$ u% }# C" X, O4 j/ x4 G
For time-domain analysis, an impulseresponse obtained from the frequency-domain analytical model is used. Thiscomponent has no default artwork associated with it.
" M+ E. n. i% N· The "Temp" parameter is only used in noisecalculations.
9 \# z* ~/ p2 ]$ r7 W9 N1 V· For noise to be generated, the transmission line must belossy (loss generates thermal noise).
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5.小节:
+ P' t2 S$ { _3 A. H4 I* y调节ADS 中的参数可以仿真出巴伦对应的传输损耗;
; R7 i' r+ \6 c9 ?1 }0 Z+ c% J介电常数环节需要进一步讨论;. 6 g# v) i v& u0 b. ?
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