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RF Electronics Chapter 7: RF Filters Page 258 2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0. Figure 7.76. Resonator loading and coupling test circuit for hairpin filters. Figure 7.77. Filter performance with parameters as calculated. Figure 7.77 shows the initial frequency response of the four 5-resonator filters, when the tapping and coupling gaps are set to those calculated using the test circuits. The performance of all these filters is close enough that the specifications can be met using some simple optimisation. The tuning and optimisation is best done in three stages: Firstly adjust the resonator length using manual tuning, to give the correct centre frequency. The second step is to fine-tune the coupling gaps and tapping points using optimisation, to get as close to the requirements as possible. The final step is to allow the individual resonator lengths to be optimised as well as further minor optimisation of the coupling gaps and resonators. Since there is a significant interaction between the parameters to be optimised, the local random optimisation is most likely to result in the best optimisation. If the optimisation gets stuck, changing the weight of the worst error may get the optimisation out of the local minima and thus result in lower error costs. PORT P=2 Z=1000000 Ohm PORT P=1 Z=50 Ohm MLIN ID=TL1 W=Wr mm L=Lcr-Lct-0.1-W50 mm MLIN ID=TL7 W=Wr mm L=Lct mm MLEFX ID=TL5 W=Wr mm L=0.1 mm 1 2 3 MTEEX ID=TL4 MCURVE ID=TL2 W=Wr mm ANG=90 Deg R=4 mm MSUB Er=3.38 H=0.8128 mm T=0.035 mm Rho=0.7 Tand=0.0027 ErNom=3.38 Name=RO/RO1 MLIN ID=TL6 W=W50 mm L=5 mm W W 1 2 3 4 MCLIN ID=TL1 W=Wr mm S=Scrc mm L=Lcr-0.1 mm MLIN ID=TL9 W=Wr mm L=Lcr-0.1 mm MCURVE ID=TL2 W=Wr mm ANG=180 Deg R=4 mm MLIN ID=TL10 W=Wr mm L=0.1 mm MLEFX ID=TL13 W=Wr mm L=0.1 mm 1 2 3 MTEEX ID=TL3 MLEFX ID=TL7 W=Wr mm L=0.1 mm MLIN ID=TL8 W=Wr mm L=Lcr-0.1-0.1-W50 mm MLIN ID=TL6 W=W50 mm L=5 mm MCURVE ID=TL5 W=Wr mm ANG=180 Deg R=4 mm MSUB Er=3.38 H=0.8128 mm T=0.035 mm Rho=0.7 Tand=0.0027 ErNom=3.38 Name=RO_RO1 MLEFX ID=TL11 W=Wr mm L=0.1 mm MLEFX ID=TL4 W=Wr mm L=0.1 mm Scrc=0.95 PORT P=2 Z=1000000 Ohm PORT P=1 Z=50 Ohm RF Electronics: Design and Simulation 258 www.cadence.com/go/awr