A Planar Duplexer with Steep Sidebands Based on Bandpass Bandstop Mixed Structure

Abstract

The invention provides a sideband steep plane duplexer based on a band-pass band-elimination hybrid structure. The sideband steep plane duplexer comprises an upper layer microstrip structure, a middle dielectric substrate, and a bottom layer metal floor, wherein the upper layer microstrip structure consists of a first band-pass filtering network, a second band-pass filtering network, a T-type branch line, a first resonator and a second resonator. By adoption of the stub-loaded resonators, the volume is reduced while the loss is lowered; in addition, based on the characteristics of the resonators, multiple transmission zero points are formed by a low-frequency filtering network at a high-frequency band while transmission zero points are also generated by a high-frequency filtering network at a low-frequency band, so that a good suppression effect is achieved without improving the complexity of the circuit; meanwhile, by adoption of the design theory of a band-elimination filter, the transmission zero points are generated in the edge frequencies of the low-frequency band and the high-frequency band, so that high roll-off characteristic of the edge frequencies is obtained; and the sideband steep plane duplexer provided by the invention is not only suitable for wide frequency band but also applicable to two quiet close working frequency bands, and has creativity and practicability.

Description

technical field [0001] The invention relates to a duplexer, in particular to a duplexer based on a multi-mode resonator that can be applied to a radio frequency front-end circuit. Background technique [0002] In the field of wireless communication, duplexers are in great demand. By accessing a duplexer, the wireless receiver and transmitter can share an antenna, which greatly reduces the size of the system. The duplexer should have a small insertion loss, so as to improve the signal-to-noise ratio received by the antenna; at the same time, it should have a high isolation to prevent the signal coupling of the transmitting end, such as the receiving end, from burning out the receiver. In recent years, scholars at home and abroad have carried out a lot of research on duplexers. The cavity duplexer with the best performance has the characteristics of low insertion loss and high isolation, but the cost is too expensive, and the volume is large and the weight is heavy, which li...

AI Technical Summary

Problems solved by technology

The simplest method is to directly introduce a quarter-wavelength open-circuit stub at the input or output port, but this will increase the size of the circuit; or use the cross-coupling method to introduce transmission zeros, but the transmission zeros generated by cross-coupling are not easy to control , and the depth of the zero is difficult to guarantee; here the transmission zero generated by a stub-loaded resonator (SLR) is used

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