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Tham khảo tài liệu 'three-dimensional integration and modeling part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CAVITY-TYPE INTEGRATED PASSIVES 41 where tan s is the loss tangent 0.0015 ofthe LTCC substrate. The quality factor Eqs. 5.2 - 5.4 of a rectangular cavity can be used effectively in the cavity using via-array sidewalls which almost match the performance of the PECs 26 29 . The loaded quality factor Qi can be obtained by adding the losses Qext of the external excitation circuit to the Qu as expressed in 61 o i ir 5.5 Qu Qext The theoretical values of Q can be extracted from the simulated performances of a weakly coupled cavity resonator using the following equations 61 fres Q 5.5 Af S21 dB 20log1J Qext 5.7 Qu Q - ob ext 5.8 where Ạf is the 3-dB bandwidth. The weak external coupling allows for the verification of Qu of the cavity resonator as Qu approaches Qj with the weak external coupling as described in 5.8 . Also the weak coupling abates the sensitivity of the measurement on the amplitude of S21. Using the above definitions a weakly coupled cavity resonator S21 20 dB has been separately investigated in HFSS and exhibits a Qu of367 at 59.8 GHz compared to the theoretical Qu of372 at 60 GHz from 6 - 8 . All fabricated resonators were measured using the Agilent 8510C Network Analyzer and Cascade Microtech probe station with 250 xm pitch air coplanar probes. A standard short-open-load-through SOLT method was employed for calibration. 5.2 THREE-POLE CAVITY FILTERS The next topology covered in this chapter has to do with three-pole filters using via walls for 60 GHz WLAN narrowband 1 GHz applications that consist of three coupled cavity resonators cavity 1 cavity 2 cavity 3 in Fig. 5.2 b . The three-dimensional 3D overview and side view are illustrated in Fig. 5.2 a and b respectively. The three-pole bandpass filter based on a Chebyshev lowpass prototype filter is developed for a center frequency of 60 GHz 3 dB insertion loss 0.1 dB in band ripple and 1.67 fractional bandwidth. To meet design specifications the cavity height H in Fig. 5.2 a was set to 0.5 mm five .
