Planar low pass band pass triplexer

Abstract

The invention discloses a planar lowpass-bandpass triplexer. The planar lowpass-bandpass triplexer comprises a lowpass filter (11), a bandpass filter (12), a bandpass filter (13) and a transmission line (14), wherein two branch node loaded resonators in the lowpass filter (11) generate two transmission zeros, the frequency of one transmission zero is identical with the center frequency of the bandpass filter (12), the frequency of the other transmission zero is identical with the center frequency of the bandpass filter (13), and accordingly center frequency signals of the two bandpass filters are under the short-circuit condition when the branch node loaded resonators are located at the input end of the lowpass filter (11); the transmission line (14) is provided with a locating point p1, a locating point p2 and a locating point p3, the distance between the p1 and the p3 corresponds to quarter wavelength of the center frequency of one bandpass filter, and the distance between the p2 and the p3 corresponds to quarter wavelength of the center frequency of the other bandpass filter; according to quarter wavelength impedance inversion, the center frequency signal of the bandpass filter (12) is under the open-circuit condition when the bandpass filter (12) is located at the p1, and the center frequency signal of the bandpass filter (13) is under the open-circuit condition when the bandpass filter (13) is located at the p2. The lowpass-bandpass filters of the triplexer are designed conveniently and independently and enabled not to influence each other, design cycles can be shortened, and design efficiency can be improved.

Description

technical field [0001] The invention relates to the technical field of planar filters, in particular to a planar low-pass band-pass triplexer. Background technique [0002] In recent years, with the rapid development of wireless communication technology, people's demand for wireless communication services is increasing day by day. In order to meet people's various needs, the communication system must be compatible with multiple communication standards when designing. Today's wireless communication systems are basically multiplexing systems. For time division multiplexing, the problem can be solved as long as the receiving and transmitting are arranged in different time slices. For frequency division multiplexing, in order to reduce the number of filter devices, the It is necessary to design a special device to isolate different signals without causing interference with each other. Such a device is a multiplexer. [0003] At present, the design of multiplexers composed of ba...

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Problems solved by technology

[0004] In 1999, M.H.Capstisk published a paper entitled "Microstriplowpass-bandpass diplexer topology" on "IEEE Electronic Letter", the structure is as follows figure 1 As shown, it simply connects a low-pass filter and a band-pass filter to form a low-pass-band-pass duplexer. This article is not detailed, and it is difficult to independently design the low-pass and band-pass filters

[0005] In 2013, Pu-Hua Deng et al published a paper entitled "Design of Microstrip Lowpass-Bandpass Diplexer" on "IEEE MICROWAVE AND WIRELESS COMPONENTSLETTERS", the structure is as follows figure 2 As shown, the low-pass filter and the band-pass filter are connected through a quarter-wavelength converter to form a low-pass-band-pass duplexer. Although the low-pass and band-pass filters can be designed independently, this structure cannot Applied to low-pass-band-pass triplexer design, and its low-pass filter performance needs to be improved

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