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Impedance Matching (2)

Impedance Matching (2). Outline. Three Element Matching Motivation Pi Network T Network Low Q or Wideband Matching Network Impedance Matching on Smith Chart Two-Element Three-Element Matching Multi-Element Matching Genesis. RV=4.424 Ohms. Component Q= 4.73. Circuit Q.

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Impedance Matching (2)

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  1. Impedance Matching (2)

  2. Outline • Three Element Matching • Motivation • Pi Network • T Network • Low Q or Wideband Matching Network • Impedance Matching on Smith Chart • Two-Element • Three-Element Matching • Multi-Element Matching • Genesis

  3. RV=4.424 Ohms Component Q=4.73

  4. Circuit Q Q of Vin/VS=102.2/(125.4-83.1)=2.416 Circuit Q is different from component Q! Q of Vout/VS=98/(117.6-73.4)=2.21

  5. Four Combinations of L-Match RL>RS RS>RL

  6. Split a Pi Network into Two L Networks

  7. Virtual Resistor Virtual Resistance must be smaller than source resistance! (Blocks DC) RS>RL RL>RS

  8. Design a Pi-Match • RS=100 Ohms • RL=1000 Ohms • Resonant Frequency: 100 MHz • Q2=15 • R2/R=(Q22+1)/(Q12+1) (See attached) Q1 Q2

  9. Calculation Design Sequence: Q1, Q2 RV L2, C2 L1, C1

  10. Pi-Match Schematic

  11. Use Pi-Match to Produce Matching at 100 MHz

  12. T-Match

  13. T-Match RL>RS RS>RL

  14. Calculation in Matlab

  15. Schematic Q1=10 Q2=4.472 RV=1050 Ohms

  16. Vin/VS

  17. Review of Smith Chart • Adding an inductor in series • Adding a capacitor in series • Adding a capacitor in parallel • Adding an inductor in parallel

  18. Adding an Inductor in Series Insertion of a series inductor to an impedance moves the impedance upward, causing a rotation clockwise along a constant circle of resistance

  19. Adding a Capacitor in Series Insertion of a seriescapacitor to an impedance move impedance downward, causes a rotation counterclockwise along a constant circle of resistance

  20. Adding a Shunt Capacitance Insertion of a shunt capacitor causes a rotation clockwise along a constant circle of admittance

  21. Adding a Shunt Inductance Insertion of a shunt inductor causes a rotation counter clockwise along a constant circle of admittance

  22. Example Design a matching network with a source impedance of 25+15j Ohm and output impedance of 100+25j Ohms.(We need to have match the source and load to their complex conjugates)

  23. Starting Smith Chart (source) (load)

  24. Four Combinations of L-Match (Series L causes clockwise Movement on constant R on smith chart… …) (The only one) RL>RS RS>RL

  25. C=39.46 pF; L=156.35 nH

  26. Constant Q Q of series impedance=ratio of reactance to resistance

  27. Constant Q Circle

  28. Example 4-4 Constant Q of 15 Q=15 The end of large terminating resistor will determine the Q.

  29. Example 4-4 (Adding a Series L) Get the admittance circuit with a series L

  30. Example 4.4 Get back with the center of chart with a shunt cap.

  31. Example 4-4 (Q=15)

  32. Compare the Smith Chart Design with Calculation in Matlab

  33. Example 4.8 • Design a T network to match Z=15+15j Ohm source to a 225 Ohm load at 30 MHz with a loaded Q of 5.

  34. Example 4.8 Get on Constant Q=5 curve

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