Practical 3. (COMS 7305) RF to DC Converters -All the details will not be covered. You need to do your research and figure out the challenges you might face. -Always cite credible journals and books, not internet websites. -Do not snapshot the whole screen for figures and circuits. Copy just the figures and plots and paste high quality of them on your report. -Do not copy/paste any sentence from any source. -Repeat the questions on your report without hints, then answer them after that. -Answer the questions in order and put all the answers after the questions. Do not use any appendix as part of your answers. -Put the “assessment coversheet” with the declaration on plagiarism as the coversheet of your report. -Pass your report through turn-it-in for plagiarism check. 1. Do a research to find out what type of diode is good for high frequency RF to DC convertors. Explain why, while describing the structure of the diode in details. Just explain the type of your selected diode. Hint: Here are some types of diodes: Zener Diode, Schottky Diode, Schottky Barrier Diode, Tunnel Diode, Laser Diode, Avalanche Diode, PIN Diode, etc… . Find out which type is the best and why? Explain its semiconductor structure and circuit equivalent in details with figures. Cite your response (consider the note on the beginning of this page about citation). 2. Investigate three applications of RF to DC convertors. Explain those with details and figures. Cite your response. 3. (a) In RF to DC convertors, which element is non-linear? (b)Write the conversion efficiency formula and explain that. Hint: Include Friis formula in your explanations. Include measurement setup figure for the Friis formula. Feriss is needed to calculated the received power to the convertor from transmitter. The source in Fig. 1 is acting as a receiver antenna. (c) Explain why non-linearity decreases the conversion efficiency. What is the solution for that? Hint: You can read [1] and [2]. 4. Design the RF to DC converter in Fig. 1 in ADS. Plot the Vout and S11. What is the input and output power in mW? Find the catalogue of SMS7631 diode and explain its specifications. Hint: To create the Vout output, double click on the wire on top of the load resistor then on the opened window choose the name as Vout. Fig. 1. Schematic of an RF to DC converter. 5. Explain the function of the circuit in Fig. 1 in positive and negative cycles. Why does the circuit have that configuration for the RF to DC conversion? Hint: Investigate about voltage doubler circuits. 6. Plot the imaginary and real part of input impedance for the circuit and explain the result. Hint: To calculate the input impedance of the circuit from S11, use the zin() function in ADS as follows: Then plot it by choosing the Equations from drop down tab as follows: 7. What are the purposes of using N-Port Boxes in ADS? How do you use them to replace the entire of the circuit in Fig. 1 with a box like in Fig. 2? Explain that in details with snapshots of your own design. Plot the S11 parameter of the design and compare it with S11 of the design in Fig. 1. Hint1: N-Port Boxes reduce the simulation time if you want to combine EM and Schematic environments simulations. Explain How. Hint2: N-Port Boxes reduce the size of big complicated designs. Explain how. Fig. 2. The circuit in Fig. 1 has been simplified with a Data-Box. Hint 3. Use the following procedure to use N-Port Boxes (use 1-port Box): To create the S-parameter file for the box, on the page that shows S-parameter of the circuit of Fig. 1, click on the S11 plot, then go to: Tools/Data file tool, then the following window will appear. Choose “Write data file from data set”. Choose “Touchstone” (that’s the format of the data). On the “Dataset name” choose the name of the circuit of Fig.1 and on the “output file name” click on browse and choose the output file name as “S-Params1”. Choose the rest of the setup as follows, then click “write to file”: Now go back to the Fig. 2 circuit design, and click on the box. The following window will pop up: Browse the S-params1 file that you saved before, as the S-parameter of the box. Click on Edit to see the file, and take a snapshot of that and put that in your report. Click OK. Now, the circuit in Fig. 2 is ready. Run it and plot S11 and compare it with the S11 plot of the circuit in Fig. 1. The plotted S11 would be positive, to edit that to be correct, follow the following procedure: 8. Calculate the conversion efficiency (?) of the RF to DC convertor in Fig. 1. Change the load, record the value of the ? for 10 different values of load. Then plot ? vs. load. Choose the point with highest efficiency. Note: Each student should select their own range for the load irrespective of others. 9. Calculate the output power (Pout) of the RF to DC convertor in Fig. 1. Change the Pin then record the value of the Pout for 10 different values of Pin (R_load=185 ohm). Then plot Pout vs. Pin. Choose the point with highest Pout. Note: Each student should select their own range for the load irrespective of others. 10. You can get higher output voltage by finding the optimum value of Pin, R_load, and frequency. Use tuning for those three variables, and find the highest V_out. Put the snapshots of your tuning window, and plot V_out for your optimum values of those three parameters. Compare it with V_out, obtained from Fig. 1. Note: Each student should get different results, even if they are very close. Do the process individually, like the other questions. References: [1] Ji-Yong Park, Sang-Min Han, and Tatsuo Itoh, “A Rectenna Design with Harmonic-Rejecting Circular-Sector Antenna,” IEEE Antennas Wireless Propag. Lett., vol. 3, 2004. [2] J. A. G. Akkermans, M. C. van Beurden, G. J. N. Doodeman, and H. J. Visser, “Analytical Models for Low-Power Rectenna Design,” IEEE Antennas Wireless Propag. Lett., vol. 4, 2005.