CHCN_8-14_K.indd

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1 是德科技矢量网络分析的基本原理应用指南

2 引言

3 (S ) DC-110 GHz 通信系统中的测量要求 ( ) ( 1) Sin 360º * f * t Input DUT A t o A * Sin 360º * f (t t o ) A phase shift = t o * 360º * f f 1 Output Linear behavior input and output frequencies are the same (no additional frequencies created) output frequency only undergoes magnitude and phase change f 1 Nonlinear behavior output frequency may undergo frequency shift (e.g. with mixers) additional frequencies created (harmonics, intermodulation) f

4 (DUT) ( 2) 3 ( 3) F(t) = sin wt + 1 /3 sin 3wt + 1 /5 sin 5wt Linear network Magnitude 2. F(t) = sin wt + 1 /3 sin 3wt + 1 /5 sin 5wt Linear network Magnitude 0º 180º 360º 3. 4

5 Nonlinear networks Saturation, crossover, intermodulation, and other nonlinear effects can cause signal distortion 4. ( 4) LC 矢量测量的重要性 (CAE) ( ) 5

6 入射功率和反射功率的基本概念 ( ) ( )( 5) ( ) ( ) Lightwave analogy Reflected Transmitted 5. 史密斯圆图 (R+jX G+jB) ( ) 6

7 0 ( 6) 50 Ω 75 Ω +jx Polar plane 90 o R ±180º o jx Rectilinear impedance plane Smith chart maps rectilinear impedance plane onto polar plane 0 Z = Zo L = 0 Z L= 0 (short) = 1180º 90º Constant X Constant R Z L= (open) = 10º Smith chart 6. 功率传送条件 R s R L R L = R S ( 7) R s = j 0.3 R s = j 0.3 ( ) 7

8 ( 8) R S Load power (normalized) R L For complex impedances, maximum power transfer occurs when Z L = Z S * (conjugate match) Zs = R + jx R L / R S Maximum power is transferred when R L = R S Z L = Zs * = R jx 7. Zs = Zo Zo = characteristic impedance of transmission line Zo V inc V refl = 0 (all the incident power is absorbed in the load) For reflection, a transmission line terminated in Zo behaves like an infinitely long transmission line 8. Z 0 8

9 ( ) ( 9) ; 108 ( ) Ω 1/ :1 / VSWR ( ) VSWR ( VSWR) Zs = Zo V inc V refl In phase (0º) for open Out of phase (180º) for short For reflection, a transmission line terminated in a short or open reflects all power back to source 9., 9

10 网络分析的名词术语 R A B ( 10) ; (DUT) ( ) ( ) A/R B/R R Reflected A Reflection Transmitted B Transmission Reflected = A R Transmitted = B R SWR S-parameters S11, S22 Reflection coefficient, Return loss Impedance, admittance R+jX, G+jB Gain/loss S-parameters S21, S12 Transmission coefficient T, Group delay Insertion phase 10. G 11G ρ Z o V refi = 0 ρ = 0 Z L ρ 0 ρ = 1 ρ 0~1 10

11 Reflection coefficient No reflection (Z L = Zo) = V reflected V incident = r F Return loss = 20 log( ), = Emax Emin = Z - L Z O Z L + Z O Voltage standing wave ratio VSWR = Emax Emin = 1 + r 1 r Full reflection (Z L = open, short) 0 1 db RL 0 db 1 VSWR 11. (db) db ( ) 0 db ( ) (VSRW)VSRW ρ (1 + ρ)/(1 - ρ)vswr 1 ( ) ( ) ( 12) V DUT V Transmitted Transmission coefficient = T V Transmitted = = V Insertion loss (db) = 20 Log V Trans V Inc = 20 log Gain (db) = 20 Log V Trans V Inc = 20 log

12 ( ) (13 ) Use electrical delay to remove linear portion of phase response Phase 45º/div RF filter response Low resolution Linear electrical length added (Electrical delay function) + yields Deviation from linear phase High resolution Phase 1º/div 13. 测量群时延 ( 14) ( ) tg Group delay t o Group delay Average delay Phase Group delay (tg) = d = o * d d f Deviation from constant group delay indicates distortion Average delay indicates transit time f in radians in radians/sec in degrees f in Hz ( = 2 )

13 - ( 15) Phase Phase dφ d f dφ d f Group delay Group delay f Same peak-to-peak phase ripple can result in different group delay f 15.? 网络的表征 ( ) HY Z S ( 16) S S S CAE HY Z S S 4 S S S S ( S 11 ) 13

14 H,Y, and Z parameters Hard to measure total voltage and current at device ports at high frequencies Active devices may oscillate or self-destruct with shorts or opens S-parameters Relate to familiar measurements S (gain, loss, reflection coefficient, etc.) 21 Transmitted a 1 Relatively easy to measure S 11 Reflected DUT S 22 Can cascade S-parameters of multiple Port 1 Port 2 b Reflected devices to predict system performance 1 a 2 Transmitted S 12 Analytically convenient b 1 = S 11 a CAD programs 1 + S 12 a 2 b 2 = S 21 a 1 + S 22 a 2 Flow-graph analysis Can compute H, Y, or Z parameters from S-parameters if desired b2 16. HY Z ( S?) Forward S 21 b Transmitted 2 a 1 S 11 Z 0 b Reflected DUT Load 1 a 2 = 0 Reflected S 11 = S 21 = Transmitted = b 1 a 1 a 2 = 0 = b 2 a 1 a 2 = 0 Reflected S 22 = S 12 = Transmitted = b a = b a 2 a = 0 1 a = 0 1 Z 0 Load a 1 = 0 b 1 DUT Transmitted S 12 b 2 S 22 Reflected a 2 Reverse 17. S S S 11 S 21 ( ) S S 22 S 12 ( 17) 14

15 Related Literature Exploring the Architectures of Network Analyzers, Application Note , Literature number E Applying Error Correction to Network Analyzer Measurements, Application Note , Literature number E Network Analyzer Measurements: Filter and Amplifier Examples, Application Note , Literature number E 15

16 16 Keysight mykeysight 3 年保修 3 : 是德科技保证方案 5,, Keysight Electronic Measurement Group DEKRA Certified ISO 9001:2008 Quality Management System 是德科技渠道合作伙伴 : 如欲获得是德科技的产品应用和服务信息, 请与是德科技联系如欲获得完整的产品列表, 请访问 : 请通过 Internet 电话传真得到测试和测量帮助热线电话 : 热线传真 : 是德科技 ( 中国 ) 有限公司 : 3 : (010) : (010) : 上海分公司 : : (021) : (021) : 广州分公司 : : (020) : (020) : 成都分公司 : 116 : (028) : (028) : 深圳分公司 : 3 : (0755) : (0755) : 西安分公司 : 88 D 5/F : (029) : (029) : 是德科技香港有限公司 : : (852) : (852) : : (852) Keysight Technologies, 2014 : CHCN : :

CHCN_8-14_K.indd

CHCN_8-14_K.indd 是德科技三个理由让您选择深存储快响应示波器应用指南介绍 1. 更长的波形捕获时间 = / 1 1 Mpts 10 GSa/s 1 2 100 Mpts 10 1. = / 1 Mpts 10 GSa/s 1 ms 2. = / 100 Mpts 10 GSa/s 10 ms 3 12.5 Mpts 3 300 Kpts 3 3. 3 12.5 Mpts 3 300 Kpts? Agilent