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0 v- t9 a: L( M! d; o8 J; c传输线 巴伦
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) V) h6 |, [, k9 b" C! v1.基本原型:2 T: \+ m2 Q6 G+ d v4 c
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4 S1 n; Z, C$ e4 k# q2.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 & I4 ?1 P. E+ E0 d, T$ V+ F. v4 r
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3.相关公式
- `* r/ t) M4 h6 ~' S7 E3 X+ C3.1传输损耗公式:8 x' k% J; Q; L+ x
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w. l8 B7 a" m+ ]4 q3.2反射损耗公式为:
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; ^. N( M2 v$ I* f( E* `4 ^' N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。 1 S* N& q7 F7 `" i, `/ {5 T5 F
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3.3磁导率) d2 B" |. a. D( l T
铁氧体磁芯磁导率随频率变化的影响: $ w' n A. @6 \" R( ^/ o3 o$ @
磁导率随频率 变化的公式为 ( l6 I% Y. O# b! R5 H0 T- _
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+ [$ s: i# Z4 C; `% x& S' J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。 - c3 ]1 S5 K) C. @+ k$ L
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) G2 P8 U3 D: q- j0 V* g2 f# \4.ADS 中低端巴伦模型 C8 } T: d' m' X8 [. B
/ o; m2 s* E3 N8 g" wBALUN1 (Balanced-to-Unbalanced Transformer (Ferrite Core))
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/ b+ t" D" D" P. Y+ W- b1 }+ F% HRange of Usage
' ^' @1 J( K1 v$ AZ > 0, Len > 0, AL > 0, E/ C+ y* R# p5 y
K ≥ 1. L; P, E2 ]% j6 a9 B8 k' W/ Z0 v
A ≥ 0
7 X# T) }1 y1 f. U( \F ≥ 0
% d0 W; p% o f5 zN ≥ 1 % B+ T8 w, H. }
Parameters 0 C0 ~2 J! U3 ~4 `, @, J- A% U' X
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 |
" G- w. w+ J& `: e: L1 ~$ ]· This component is a length of transmission line(specified by Z, Len, K, A and F) coiled around a ferrite core.
5 U9 J' F7 d6 m5 ~; fChoking inductance Lc accountsfor low-frequency roll-off and is given by" P6 ?' y, h* |
Lc = N2 × AL
- H9 b2 G) R9 S v$ T BA(f) = A (for F = 0)
5 x: j7 B0 x0 A* V( r0 Z- a' F' kA(f) = A(F) × file:///C:/Users/wanghai/AppData/Local/Temp/msohtmlclip1/01/clip_image013.png/ C+ K" P( k6 D
(for F ≠ 0)' o6 T4 W) `+ u; W5 L
where$ f6 J6 Q$ |( Y3 H' E' A, W+ m3 C! a
f = simulation frequency* `2 Y; U. j: ?' O+ V
F = reference frequency for attenuation
2 o+ O) }) R0 X! j0 kFor time-domain analysis, an impulseresponse obtained from the frequency-domain analytical model is used. Thiscomponent has no default artwork associated with it. 4 X+ @' |) C# ?
· The "Temp" parameter is only used in noisecalculations.
3 m: K% K" T2 J) Z% O. h2 ^· For noise to be generated, the transmission line must belossy (loss generates thermal noise).
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5.小节:
& w2 i( u* u- J* H/ }$ J( |4 P9 d调节ADS 中的参数可以仿真出巴伦对应的传输损耗;
) z6 S5 \+ V- F4 S* s: @介电常数环节需要进一步讨论;. + X: B ?' r% g) B
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