Dissertation in RF Engineering (Presented - 01-10-10)

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MSc - Mobile Communication Dissertation by Sankar Velama

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Dissertation in RF Engineering (Presented - 01-10-10)

  1. 1. Design of 3-dB Band Pass Filtered Power Divider<br />SankarVelama --- 0926188<br />MSc Mobile Communications<br />Supervisor : Dr. Kenneth Yeo<br />
  2. 2. Aim & Objectives :<br /><ul><li>To advance the present trend in RF/Microwave engineering & more specifically to design a 3-dB Band Pass Filtered Power Divider.
  3. 3. To achieve the response of the band pass filter & the power divider simultaneously.
  4. 4. To achieve desired circuit & microstrip layout.
  5. 5. To simulate the design & present it’s results.
  6. 6. To make the analysis & find out the future enhancements.</li></li></ul><li>Need for this Project <br /><ul><li>Consider any balanced LNA with a band pass filter , normally used in satellite receivers, radiometers, transceivers & W-CDMA receivers.
  7. 7. The proposed diagram represents how the complexity of a conventional design can be reduced.</li></li></ul><li>Specification of the design<br />
  8. 8. 3rd Order Band Pass Filter using Chebyshev prototype <br /><ul><li>The normalised low pass parameters were calculated
  9. 9. Frequency & impedance scaling
  10. 10. Shunt only & Band pass transformation
  11. 11. Coupling coefficient, K
  12. 12. External Quality factor, Qext
  13. 13. Circuit model implementation</li></ul>Spread Sheet for all the Calculations<br />
  14. 14. Schematic of a 3rd order band pass filter<br />Agilent ADS was used to design the circuit & microstrip layouts. <br />
  15. 15. J-inverter model for 3rd order band pass filter <br /><ul><li>The next part of the implementation is to convert schematic level in terms of j-inverter.</li></li></ul><li>Schematic for 3-dB Band Pass Filtered Power Divider<br />Simulation response :<br />1. Before optimization<br />2. After optimization<br />
  16. 16. Microstrip Layout Design <br /><ul><li>The required geometries for microstrip design such as width & length were calculated using MS-Excel.
  17. 17. Using the above parameters, there are four different designs were developed.</li></li></ul><li>Design Procedure for Microstrip Layout<br /><ul><li>Determine the desired shape & length of the resonator
  18. 18. Use the theoretical coupling coefficients to relate with the coupling spacing’s
  19. 19. Extract the external Q-factor in order to connect input & output ports
  20. 20. Build the final layout using all the previous steps.
  21. 21. Simulate the overall design and tune the physical layout to achieve desired value.</li></li></ul><li>Microstrip Design - 1<br />Simulation Response<br />
  22. 22. Microstrip Design - 2<br />Simulation Response<br />
  23. 23. Microstrip Design - 3<br />Simulation Response<br />
  24. 24. Microstrip Design - 4<br />Simulation Response<br />
  25. 25. Conclusion<br /><ul><li>This research represents one of the first efforts to advance the present trend in RF/Microwave engineering especially on balanced LNA designs.
  26. 26. The design & implementation of 3-dB band pass filtered power divider for circuit & microstrip layouts were executed successfully.
  27. 27. The agreement between the predicted & the obtained values of insertion losses (S21 & S31) & return loss (S11) were strong enough for fabrication.</li></ul>Future Research <br /><ul><li>However, insights from this research can only provide a filtered power divider, whereas power combining is not possible due to the poor isolation between the output ports, hence this drawback can be consider for future research.</li></ul>Thank You...!<br />

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