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[. o- u& B3 P) T传输线 巴伦
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1.基本原型:
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% J% R3 k& R& D% z$ y: K2.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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3.相关公式
5 }/ B0 u& q8 j3.1传输损耗公式:
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' H3 f5 p6 @9 |$ n3 J3.2反射损耗公式为:
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# f. D& c$ N2 U- d- ?) u* e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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* V+ q7 w- X7 `3.3磁导率, @; W t( ^! ]3 T
铁氧体磁芯磁导率随频率变化的影响:
8 s, V2 c0 X' D# M- k; C; L磁导率随频率 变化的公式为
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# ?( P. ?' }5 \$ V1 y' V: |; [式中,S为斯诺克常数,,fr为截止频率。
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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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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。 & X0 [% ~. y5 O9 ]! U
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& @ A, U& |9 t4.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
+ ^6 J. y0 |( H" s' a2 IZ > 0, Len > 0, AL > 0
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6 z0 ~& n( a* DA ≥ 0
) u5 G* t- N/ Y, E% eF ≥ 02 a1 g1 I, `* j( U; I/ Y
N ≥ 1
& }2 i' w& R/ Y! Z5 sParameters
+ u/ B& }. C$ z8 B4 f9 q 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 |
( V9 S: @' L. Y/ U; `, N4 Q' H h· This component is a length of transmission line(specified by Z, Len, K, A and F) coiled around a ferrite core.
+ {# L a5 _( ~/ {/ |" R/ ]/ K3 i7 hChoking inductance Lc accountsfor low-frequency roll-off and is given by
( Z5 J B) Z) F9 QLc = N2 × AL
& h6 z9 o9 Y8 q2 iA(f) = A (for F = 0)
. {1 [; }1 _; \A(f) = A(F) × file:///C:/Users/wanghai/AppData/Local/Temp/msohtmlclip1/01/clip_image013.png- a- R! _. {6 q( t; j j7 h( {
(for F ≠ 0)
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f = simulation frequency
9 E. U) p6 X0 A( s+ w4 e: ]F = reference frequency for attenuation
) y* Y/ T* P# a* n6 e( VFor time-domain analysis, an impulseresponse obtained from the frequency-domain analytical model is used. Thiscomponent has no default artwork associated with it. 4 w0 w# _0 _% d% n8 Q
· The "Temp" parameter is only used in noisecalculations.
; w2 W" a4 h4 H6 E6 a$ A, O3 G0 S( o4 |· For noise to be generated, the transmission line must belossy (loss generates thermal noise). 8 b5 V- u" Y. G: G: R4 o8 A" q, x; f
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5.小节:* i8 S( I7 N, F) E. p
调节ADS 中的参数可以仿真出巴伦对应的传输损耗; ( |9 z' c7 h0 y- W( |
介电常数环节需要进一步讨论;.
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