Research On The Integration Of Miniaturized Multifunctional Filter And Power Splitter

With the development of the wireless communication system,the requirements of RF circuit are higher and higher.As two kinds of important passive devices in RF systems,filters and power dividers have also been fully studied by scholars.These two devices are often used in the RF front-end circuit at the same time,occupying a large area,resulting in the whole RF system too large.In order to achieve both filtering and power dividing,the power divider and the filter can be integrated to design a filtering power divider with two functions,which can not only reduce the overall area of the system,but also reduces the loss and improves the performance of the system.This paper mainly studies the filtering power dividers with multi-functions,such as multi-band,wideband and harmonic suppression.On the basis of multi-mode resonator and transversal signal interference,the design theory of filtering power divider is introduced.Based on this theory,four types of filtering power dividers are designed,including a dual-band filtering power divider,a triple-band filtering power divider,a wideband filtering power divider with harmonic suppression and a dual-wideband filtering power divider.The dual-wideband and triple-band filtering power divider in this paper are designed based on the transversal signal interference.These structures both replace the quarter-wavelength transmission lines of Wilkinson power divider with the transversal signal interference structure,and adds a quarter-wavelength matcher before and after the transversal interference part.By adjusting electrical length of the transversal filtering structure,thus realizing the adjustment of frequency band number and bandwidth.Both two filtering power dividers have good frequency selectivity,the two 3dB relative bandwidths of dual-wideband filtering power divider reach26.6%and 13%respectively and the triple-band filtering power divider is 18%,12%and 8%respectively.In this paper,four Stepped-Impedance Resonators?SIRs?are fully used in the dual-band filtering power divider to realize two passbands in a small size.The isolation and frequency selectivity of the filtering power divider are improved by introducing source-load coupling.Finally,a wideband filtering power divider based on Stub-Loaded Resonator?SLRs?is designed in this paper,which has both wideband and good harmonic suppression performance,3dB relative bandwidth reaches 28%,and out-of-band inhibition can reach 2.6f₀ at-20dB level?where f₀ is the central frequency of passband?.The overall size of the resonator is greatly reduced by using only a single resonator.By loading branches at the input and output ports,the frequency selectivity characteristics and the suppression level at the higher harmonics are improved.