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1、 Lecture 3 : Impedance matching in narrowband caseRichard Chi-Hsi Li 李缉熙Cellular phone: 13917441363 (PRC)Email : 1. Introduction2. Impedance Matching by Means of Return Loss Adjustmento Return Loss Circles on Smith Charto Relationship between Return Loss and Impedance Matching o Implementation of an
2、 Impedance Matching Network3. Impedance Matching Network Built by One Parto One Part Inserted into Impedance Matching Network in Series o One Part Inserted into Impedance Matching Network in Parallel4. Impedance Matching Network Built by Two Partso Regions in the Smith Charto Value of Partso Selecti
3、on of Topology5. Impedance Matching Network Built by Three Partso “” and “T” Typeso Recommended Topologies6. Impedance Matching when ZS or ZL is not 50 Parts in an Impedance Matching Network Lecture 31Richard Li, 2008Figure 1 A trace displayed in Smith Chart from RL (S11 or S22) testingcovers a band
4、width BW = fH - fL RL (S11 or S22) testingWEVNUSOZfLZfHZfcZfminZfmax1. IntroductionLecture 32Richard Li, 20082. Impedance Matching by Means of Return Loss Adjustmento Return Loss Circleson Smith ChartNote 1: Power reflection coefficient, , and return loss, RL ( S11 or S22), is bold-marked with value
5、s along the vertical axis, V, such as, =1, RL=0 dB, =0.79, RL=-1 dB, =0.63, RL=-2 dB, and so on.Note 2: Normalized resistance, r, is bold-marked with values around the biggest circle, Such as, 0, 0.1, 0.2, 0.5, 1, 1.5, 2, 3, 5, 10, , -10, -5, -3, -2, -1.5, -1, -0.5, -0.2, -0.1.Note 3: Normalized rea
6、ctance, x, is bold-marked with values along the horizontal axis U, Such as, 0, 0.2, 0.5, 1, 2, 5, .Figure 2 Constant return loss S11, dB or S22, dB circles on Smith ChartVUEWNOS105321.510.50.2-0.2-0.5-5-3-2-1.5-10.20.5152-100=0.79, RL=-1 dB=0.63, RL=-2 dB=0.50, RL=-3 dB=0.40, RL=-4 dB=0.32, RL=-5 dB
7、=0.25, RL=-6 dB =0.20, RL=-7 dB=0.10, RL=-10 dB=0.03, RL=-15 dB =0.01, RL=-20 dB=1.00, RL= 0 dB=0.00, RL= - Lecture 33Richard Li, 2008o Relationship between Return Loss and Impedance MatchingRL = S11 or S22 = - 15 dB, r = 0.6980 and 1.4326, R = 34.9020 and 71.6291. Table 1 Variation of return loss R
8、L along with U axis (V=0)Resistance, ReferenceNormalizedPower Ref. Return loss,RLR,resistanceresistance, rcoefficient,S11 or S22 Ro, r=R/Ro = 2 dB2.8750500.05750.79-1 5.7313500.11460.63-2 8.5500500.17100.50-3 11.3136500.22630.40-4 14.0066500.28010.32-5 16.6140500.33230.25-6 19.1236500.38250.20-7 21.
9、5252500.43050.16-8 23.8110500.47620.13-9 25.9747500.51950.10-10 29.9240500.59860.06-12 34.9020500.69800.03-15 40.9091500.81820.01-20 44.6760500.89350.00-25 46.9347500.93870.00-30 48.2528500.96510.00-35 49.0099500.98020.00-40 49.4408500.98880.00-45 49.6848500.99370.00-50 50.0000501.00000.00(-Infinite
10、) 50.3172501.00630.00-50 50.5655501.01130.00-45 51.0101501.02020.00-40 51.8105501.03620.00-35 53.2656501.06530.00-30 55.9585501.11920.00-25 61.1111501.22220.01-20 71.6291501.43260.03-15 83.5450501.67090.06-12 96.2475501.92500.10-10 104.9942502.09990.13-9 116.1431502.32290.16-8 130.7280502.61460.20-7
11、 150.4750503.00950.25-6 178.4900503.56980.32-5 220.9700504.41940.40-4 292.4050505.84810.50-3 436.2200508.72440.63-2 869.55005017.39100.79-1RL = S11 or S22 = - 10 dB r = 0.5195 and 1.9250 R = 25.9747 and 96.2475 RL = S11 or S22 - 10 dB Lecture 34Richard Li, 2008o Implementation of an Impedance Matchi
12、ng Network BNetwork AnalyzerRF BlockImpedance Matching NetworkS11 or S22 testingFigure 3 Set-up for impedance matching from input impedance of an original RF block to 50 Arm BranchUn-matched port3 12450 ALecture 35Richard Li, 2008ArmBranchEquivalent toEquivalent toororA branch consists of one part i
13、n the impedance matching network.it is a connected component in “vertical” direction (in parallel). Figure 4 Representation of arm or branch consists of one part. An arm consists of one part in the impedance matching network. it is a connected component in “Horizontal” direction (in series). Lecture
14、 36Richard Li, 20083. Impedance matching Network built by One Parto One part Inserted into Impedance matching Network in seriesFigure 6 Pulled directions of impedanceby the insertion of an inductor or a capacitor in series in Smith ChartWEV NUSOP CSLS0f0 XL XCX, j+ 0- + 0Figure 5 Variation of reacta
15、nce when impedancematching network is inserted with onepart, either inductor or capacitor, inseries.Lecture 37Richard Li, 2008Figure 8 Pulled directions of impedance by the insertion of an inductor or a capacitor in parallel on Smith ChartWEV NUSOP CPLP0B ,jf0 YL YC+ 0- + 0Figure 7 Variation of susceptance when impedancematching network is inserted with one part, either inductor or capacitor, in parallelLecture 38Richard Li, 2008Figure 9 Pulled directions of impedance by the insertion of L, C, or R on Smith ChartWEV NUSORPP CPCSLSLPRSLecture 39Ri
