Research For Integration Of Multi-functional Power Divider

The miniaturization of the radio frequency (RF) front end is one of the tendencies in the development of wireless communication technology. In traditional RF circuits, all kinds of passive devices are designed individually then connected together in cascade, which is not conducive to the miniaturization of the RF front end. Therefore, as an efficient way to minimize the size and reduce the cost, the integration of multifunctional passive devices becomes the hot research area.A power divider is an important passive device in the feed network of the RF front end. It is of significance in theory and applications to focus on the integration of multifunctional power divider in this thesis.In the thesis, combining with the power divider theory and mixed mode S-parameters, a novel five-port single-ended to differential-ended power divider was proposed firstly, which realized the integration of the power divider and balun. Then, according to the design theory of the filter, a power divider with good filter performance is designed with with cascade coupled line structure. Finally, based on the first two parts, transforming the filter power divider into differential, a filter power divider with differential charac-teristics was designed, which realized the integration of power divider, filter and balun further. The main contents and novelties are as follows:1. The scattering parameters of the mixed mode are analyzed. Under two kinds of network with full balance port and the hybrid port respectively, the conversion rela-tionship between the parameters of the single ended S parameters and the mixed mode S parameters is presented.2. Based on the Wilkinson power divider, a novel X band (9GHz-11GHz) five-port single-ended to differential ended power divider is designed and fabricated by com-bining the mixed mode S-parameters and odd-even mode analysis, in which a stepped impedance line with open stubs is used between differential pairs for broadening the bandwidth. Measured results comply with the simulated results. A proper performance for differential mode signal is achieved. For example, the insertion loss is better than 4.6dB, the isolation is below-15dB, and the return loss is below-12 dB. In addition, the common mode suppression is reached as well.3. Combining the method of equivalent circuit and electromagnetic simulation, a novel power divider with good filtering response in X band (9.5GHz-10.5GHz) is designed and fabricated by using stepped impedance lines and a stub loaded resonator structure, in which the stepped impedance line is used for coupling line in order to make the divider with compact size, high in-band selectivity and out-band suppression. The measured results are in agreement with the simulation curve. The insertion loss is better than 3.8dB. The input return loss is below-17dB and the output return loss is below -20 dB. The isolation between two outputs is also below-16dB.4. Combined with the contents of the first two parts, the theory of differential power divider is applied in the filter power divider. A novel X band (9.5GHz-10.5GHz) differential filter power divider is designed and fabricated with power divider, filter and balun integrated in one device. The measured results agree with the simulation results. It can be seen that the common mode signal is suppressed. Also a proper performance for differential mode signal is achieved. The insertion loss is better than 4dB, the return loss is below-13dB and the isolation is also below -20dB.