Design And Chip-level Realization Of Multi-Functional Three-port RF Passive Devices

With the rapid development of 5G technology,multi-mode mobile communication systems coexist and radio frequency(RF)devices have to have the ability of multi-band operation.At the same time,the miniaturization trend of RF circuits and chips has attracted more and more attention in recent years.The application of integrated circuit technology can effectively deal with the contradiction between the reduction of circuit volume and the complexity of circuit when 5G terminal devices are thinner and thinner.Aiming at new characteristics of the development of RF devices in the 5G era,this thesis studies sub-6GHz three-port RF devices and miniaturized RF chips based on the integrated passive device(IPD)technology.The main works of this thesis are as follows:1.A filtering Gysel power divider is proposed.According to the structure characteristics of the traditional Gysel power divider,the idea of filtering integration is put forward.The closed-form expressions of circuit parameters are established by using the odd-and even-mode circuit analysis.A filtering Gysel power divider whose amplitudes of the reflection coefficients are less than-10 dB and the isolation is 17.38 dB at the center frequency is realized,which achieves better out-of-band suppression characteristics on the basis of retaining the original characteristics of Gysel power divider.2.A tri-band power divider with independent controllable power division ratios is proposed and the theoretical analysis of a tri-band impedance transformer is included.The input impedances of two output paths are controlled by the impedance transformers,which affects the power division from input port to output ports.As a result,the power division ratios at three frequencies are controllable,and the flexibility of the power divider is improved.A design example which works at three bands of 4G/5G with power division ratios of-4.44 dB,0.00 dB and-3.10 dB is realized.3.A filtering Marchand balun chip based on spiral coupled lines is proposed.Because the spiral coupled lines cause a new matching problem,the circuit structure of the traditional Marchand balun has to be altered.a capacitor termination is used to replace the open end of the traditional Marchand balun and the electrical length included in the traditional Marchand balun is changed.In view of the above changes,new parameter expressions are given,and the input impedance,transmission coefficients,phase imbalance,and amplitude imbalance are discussed.Meanwhile,a filter is added to realize a filtering function.A balun chip with a size of 1.49 mm × 1.39 mm is designed and implemented.