Research And IPD Chip-level Realization Of Microwave And Millimeter-wave High Selectivity Microstrip Filters

With the progress of wireless communication technology,radio frequency(RF)devices are developing towards broadband and miniaturization.In order to meet the demand of wideband and solve the problem of exhaustion of spectrum resources,the expansion of communication frequency band to high frequency has become inevitable.Besides,device miniaturization has become an important impetus for the development of integrated circuit technology.In view of the above research background,sub-6 GHz high-selectivity wideband bandpass filters and a miniaturized millimeter-wave filter chip based on integrated passive device(IPD)technology are designed and implemented in this thesis.The main research contents are as follows.(1)A wideband bandpass filter with multiple transmission poles and zeros is proposed.The even-and odd-mode equivalent circuits of the filter are analyzed and the complete expressions of transmission poles and transmission zeros frequency are derived.The tunability of the operating bandwidth is also explained.A design example is simulated and fabricated.The measured results show that the relative bandwidth of the filter is 50.9%and the return loss is higher than 12.1 dB.Six transmission zeros exist in the stopband to ensure the steep roll-off rate and better than 24.9 dB stopband rejection.(2)A wideband high-selectivity and high stopband rejection bandpass filter is introduced.The odd-and even-mode analysis method is used to theoretically analyze the filter circuit in detail.Moreover,the variation of transmission poles and zeros against the circuit parameters is shown.A filter which has five transmission poles and the relative bandwidth of 64.4%is achieved.The upper and lower stopband rejection are better than 29.6 dB and 28.5 dB,respectively.The measured transmission zeros nearer the passband improve the frequency selectivity of the filter.(3)An IPD millimeter-wave bandpass filter based on stepped-impedance coupled-line dual-mode resonator is demonstrated.The novel operating type of the resonator and the generating position of the resonant frequency points are introduced.A bandpass filter with simple structure is constructed,and a filter chip example working at 35 GHz band with the bandwidth of 4.63 GHz is realized by using IPD technology.The measured minimum insertion loss is 0.74 dB,and the rejection in the low frequency stopband is higher than 21.1 dB.The circuit size of the filter chip is only 1.43 mm × 0.54 mm.