1 / 256

射频工程基础 Fundamentals of RF Engineering

射频工程基础 Fundamentals of RF Engineering. 学时 :60/20 学分 : 3.5. 孙利国 中国科技大学信息学院电子工程与信息科学系. 第七讲 射频收发系统中的无源器件 （ Session 7 RF Passive Device ）. 教材：以课堂讲义为主。 主要参考书： [1] “ Microwave and RF Design: A System Approach”, Michael Steer, SciTech Publishing, 2010 其它参考书：

feleti
Download Presentation

射频工程基础 Fundamentals of RF Engineering

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 射频工程基础Fundamentals of RF Engineering 学时:60/20 学分: 3.5 孙利国 中国科技大学信息学院电子工程与信息科学系

  2. 第七讲 射频收发系统中的无源器件 （Session 7 RF Passive Device） 教材：以课堂讲义为主。 主要参考书： [1]“Microwave and RF Design: A System Approach”, Michael Steer, SciTech Publishing, 2010 其它参考书： [2] “射频电路设计-理论与应用”，Reinhold Ludwig等著，王子宇等译，电子工业出版社，2002 [3] “射频微电子学”，拉扎维著，余志平等译，清华大学出版社，2006 [4] RF and Microwave Circuit Design for Wireless Communications, Lawrence Larson, Artech House, 1997 [5]”无线网络RF工程：硬件、天线和传播“， Daniel M.Dobkin 著 ，科学出版社 ，2007 [6] G. Gonzalez, “ Microwave Transistor Amplifiers: Analysis and Design”, Prentice Hall, 1997

  3. Lecture Outline • Transmission Lines Analysis • RF Network Analysis • RF Passive Components • RF Filter Reference “Microwave and RF Design: A System Approach”, Chapter 4-10

  4. Transmission Line Analysis

  5. Transmission Lines • RF: VHV-SHF (30MHz-30GHz) • VHF: frequency 30MHz-300MHz and wavelength 1m-10m • UHF:frequency 0.3GHz-3GHzand wavelength 10cm-1m • SHF:frequency 3GHz-30GHz and wavelength1cm-10cm • Size of circuit and wavelength • size << wavelength： • V(t) and I(t), • Kirchhoff circuit law (KVL and KCL) • size >> wavelength： • E(t) and H(t) ( V(t) and I(t) are not meaningful physically ) • Maxwell equations • size ~ wavelength： • V(t, z) and I(t,z), • Transmission line theory

  6. Transmission Lines I Return Current • Basics of a transmission line: • Any current injected into a system must return to the source. It will do so through the path of least impedance. • In general any line including the signal path and return path could be thought as transmission line . • Strictly a line is treated as transmission line only if its size is more than 1/10 wavelength.

  7. Voltage and current are not only function of time but also distance when the length of line is comparable with the wavelength. Transmission Lines

  8. z z+ z Δ Transmission Lines • The transmission line can be divided into segments with infinite small length Δz. • KCL and KVL remain effective in the small segment because the voltage can be thought as constant along the small length Δz. • In the small segment a equivalent circuit for transmission line is made up of inductance (magnetic field effects) and resistance ( conductive loss) in series and capacitance (electrical field effects) and conductance（dielectric loss) in parallel. L0Δz R0Δz I(z) I(z+ z) Δ + + V(z+ Δz ) G0Δz C0Δz V(z) - - z z+ z Δ L0, R0, C0, G0 are for unit length 8

  9. R0dz L0dz G0dz C0dz Transmission Lines Inductance : magnetic field effect Resistance: conductive loss Capacitance: electrical field effect conductance: dielectric loss

  10. L ∆z R∆z I(z) I(z+∆z) + + G ∆z C ∆z V(z+∆z ) V(z) - - z z+ z Δ Transmission Lines sinusoidal steady-state condition KVL： KCL： 10

  11. Ldz Cdz Transmission Lines KVL： KCL： Telegraph equations for the sinusoidal steady-state condition。 For lossless condition： KVL（Inductance）： KCL（capacitance）：

  12. Transmission Lines Wave propagation equations for V and I： +: forward propagation along +z - : forward propagation along -z 12

  13. Transmission Lines In the lossless case (R=G=0)： Time domain form: v(t) = |V0+|cos(wt–bz+q+)+ |V0–|cos(wt+bz+q–) Wave propagation T: period: time period for 180o phase change ω : Phase variation per unit time λ: Wavelength: space distance for 180o phase change β: Phase variation per unit distance.

  14. Terminated Transmission Line. Transmission Lines Voltage reflection coefficient

  15. Z b V(z), I(z) 0 Zin 1 2 Transmission Lines 0 Z E L z=0 ZL GL z=-l Gin Short Circuit: Open Circuit: Matched Load

  16. Voltage Standing Wave Ratio Z b 0 Zin Transmission Lines V(z), I(z) Z E L z z=zL z=0 Voltage Standing Wave Ratio (VSWR) ZL = Short circuit ZL = Open circuit ZL = Z0 (matched)

  17. V(d) Zin(d) d I(d) λ 2V+/Z0 2jV+ jZ0 Short Open Short Open Short Transmission Lines Short Circuit ZL=0：(Γ0=-1） 17

  18. Zin(d) V(d) d I(d) λ 2jV+/Z0 2V+ jZ0 Open Short Open Short Open Transmission Lines Open Circuit ZL→∞： (Γ0=1） 18

  19. Zin ZL Z0 ZL λ/4 Transmission Lines Matched Load ZL= Z0： (Γ0=0 ） For alll Quarter Wave Transformer 19

  20. V X Homogeneous TEM Transmission Line Transmission Lines TEM = Transverse Electromagnetic Mode E and H fields are in the transverse plane (perpendicular to the direction of propagation which is called the longitudinal direction). Not all waveguides have TEM fields. Two Wire Line The energy carried by the transmission line is in the E and H fields. Coaxial Line

  21. Transmission Lines Strip-Above-Ground Line

  22. Microstrip Transmission Lines Coplanar Waveguide(CPW) CPW

  23. Transmission Lines • Representations of a shorted microstrip line with a short (or via) at Port 2: • three-dimensional (3D) view indicating via; • side view; • top view with via indicated by X; • schematic representation of transmission line; • alternative schematic representation; and • representation as a circuit element.

  24. Smith Chart Normalized ： Impedance Zplane Conformal transform Reflection Coefficient Γplane 24

  25. Smith Chart From：

  26. Γ Γ Constant resistance lines(r=constant) x r x +1 r=0 r=1/3 r=1 r=3 r 0 1/2 +1 -1 -1/2 1/3 1 3 0 -1 z planeΓplane Smith Chart r = 0， r = 1， r→∞ As the increase of r the center of circle varies from 0 to 1 along the Γr r: 0 → ∞ Γ：Circle with radius of 1→ point（1，0） Reduced radius 26

  27. Γ Γ Constant reactance lines(x=constant) r x x +1 3 x=1 x=1/3 x=3 1 r x=0 -1 +1 x=-3 -1 x=-1/3 x=-1 -3 -1 z planeΓplane Smith Chart x→∞， x =1， x =0， x =-1， 1/3 -1/3 Center of circles are in the line of Γr=+1. The larger absolute value of x, the smaller radius x: 0 → ∞ Γ：Axis of Γr (Γx=0)→ point（1，0） Reduced radius 27

  28. Smith Chart Smith Chart 28

  29. Smith Chart Admittance Transformation There are two ways to represent the admittance： Way1：displaying admittance inZ-Smithby rotating 180o.

  30. Inductance Inductance zL=0 yL=0 Short Open Capacitance Capacitance Smith Chart • Way2： • Smith chart is rotated by itself instead of rotating Γ 180oin Z-Smith. The new Smith chart got by this way is called Admittance Smith Chart（Y-Smith). The correspondences are such that normalized resistance becomes conductance and normalized reactance becomes normalized susceptance. Open Short

  31. -j j -0.5j 0.5j -2j 2j 1 0.5 2 O/C S/C 2 0.5 1 -2j 2j 0.5j -0.5j -j j Smith Chart By Overlaying Z Smith Chart and Y Smith Chart a combined ZY-Smithis got. This combined ZY-smith chart allows direct conversion between impedance and admittances. In other words, a point in this combined chart has two interpretations depending on whether the Z-chart or Y chart display is chosen. Combined Admittance/Impedance Smith Chart Admittance Smith Chart Impedance Smith Chart

  32. Smith Chart Combined Admittance/Impedance Smith Chart

  33. Smith Chart

  34. jb=-j1.59 Yin Z0 f=500MHz jb=-j0.2 L R f=4GHz Yin Z0 Z0=50Ω L=10nH C R f=500MHz jb=j0.16 f=4GHz Z0=50Ω C=1pF jb=j1.26 Smith Chart Parallel and series connection Parallel connection of R and L elements Parallel connection of R and C elements

  35. Zin R Z0 L Zin R Z0 C Seriesconnection of R and L elements Seriesconnection of R and C elements

  36. Power matching Rs Power Matching RL Vs GND Condition for maximum power transfer (power matching): Load resistor equals to source resistor. RL=Rs=> Γv=0 => PL=PLmax和 Vl=Vs/2

  37. Power Matching For power signal, the average power is given by 37

  38. ZS + + ZL VG VL - - Power Matching For complex impedance For maximum power transfer：

  39. Power Matching Conjugate matching is needed for maximu transfer for complex impedance.

  40. Generator and Load Mismatches Γs ΓL ZG Z0 VG ZL Γin Γout Zin Zout 40

  41. Generator and Load Mismatches Γs ΓL ZG Z0 VG ZL Γin Γout Zin Zout 41

  42. Γs ZG ΓL =Γ0 Z0 VG ZL Γin Γout Generator and Load Mismatches For source and load matching to Z0（ZL=ZG=Z0)，则ΓL =Γ S= 0 It is a maximum power available from source. For lossless transmission：PL=Pin 42

  43. Generator and Load Mismatches For source and load matching to Z0（ZL=ZG=Z0)，则ΓL =Γ S= 0 It is a maximum power available from source. For load matching to Z0 but source mismatching （ZL= Z0)，则ΓL = 0 For source matching to Z0 but load mismatching （ZG= Z0)，则ΓS= 0 43

  44. Group Velocity and Phase Velocity Group Velocity is the velocity at which information moves. Phase Velocity is the velocity at which a point of constant phase moves

  45. Microwave Network Analysis

  46. iN-1 i3 i1 + + + v3 v1 vN-1 - - - I I 2 1 RF Network V V 1 Two Port 2 1 I I 1 2 i1 Port 1 Port 2 + i1 One Port Network i2 v1 + + Two Ports Network - v1 v2 - - i2 + v2 Port1 Port 2 - i4 Transmission Line: + v4 Port3 N Ports Network Port 4 - iN + Port 1 Port 2 vN Port N Port N-1 - 46

  47. RF Network I I 2 1 V V 1 Two Port 2 1 2 Conventional Network Parameters (for two ports network) I I 1 2 Impedance Parameters, z-parameters Admittance Parameters, Y-parameters Hybrid Parameters 或

  48. Reciprocal, Symmetrical, Passive Parameters RF Network • A reciprocal two-port has a response at Port 2 from an excitation at Port 1 that is the same as the response at Port 1 to the same excitation at Port 2. • Amplifiers are not reciprocal • A symmetrical two-port has the same characteristics at each of the ports. • E.G. A transmission line • A passive network has no internal sources of power

  49. YB -Y21 i1 i1 i2 i2 + + + + YA YC YC v1 v1 v2 v2 - - - - Y11+Y12 RF Network Equivalence for Reciprocal Parameters Y-parameters for π network Y22+Y12 49

  50. RF Network Equivalence for Reciprocal Parameters Z-parameters for T network ZC i2 i2 i1 i1 Z11-Z12 ZA + + + + Z12 ZB v2 v2 v1 v1 - - - - Z22-Z12 50

More Related