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RF Electronics Chapter 2: Computer Simulation Page 40 2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0. Figure 2.50. S 11 for Bandpass T model and measurements after optimisation. Running the optimiser quickly reduces the errors to very close to zero and results in both the model and the measurement having the same S parameters as shown for S 11 in figure 2.50. The component values of the Bandpass T network model shown in figure 2.48, have changed to perfectly match the values shown in figure 3.45. Touchstone files as data files have the advantage that AWR DE knows what the frequency units are i.e. Hz, kHz, MHz or GHz. The frequencies in the Touchstone file can also be used to set the frequencies for the project, using the Match_Proj_Freq_to_Datafile_Freq script. Impedance Measurements For Touchstone files and multiport networks, all the relevant parameters S 11 , S 21 , S 12 , and S 22 for all the ports must be contained in the Touchstone file. It is possible to develop suitable models for many port networks using less than all the required measurements. The three phase mains distribution transformer model developed by [27] and described at the end of this chapter is one example. To illustrate this, the Bandpass T transformer model described above is also developed using impedance measurements, made by measuring impedances between each of the 3 terminals of the network of figure 2.48. Similarly, to the S parameter measurements described above, the impedances are calculated by AWR DE and saved as a data file. The Bandpass T network has 3 terminals and the impedances between each of those terminals can be measured using Mixed Mode Converter (MMCONV) elements in AWR DE, as shown in figure 2.51. The differential (Diff) port (1) on the MMCONV, measures the difference in the voltages and currents between terminals 3 and 4 of the MMCONV. To prevent the impedances connected to the Common mode (Comm) terminals (2) of the MMCONV to affect the measured impedances, the Common mode terminals on the MMCONV must be left an open circuit. The MMCONV element provides an isolation, so that the impedance at ports 1 to 3, do not affect the measured impedances. For the analysis to be performed without errors, one point in the circuit needs to be earthed, as shown in figure 2.51. RF Electronics: Design and Simulation 40 www.cadence.com/go/awr

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