CN-122000655-A - Five-mode reconfigurable microstrip line filter

CN122000655ACN 122000655 ACN122000655 ACN 122000655ACN-122000655-A

Abstract

The invention discloses a five-mode reconfigurable microstrip line filter which adopts unified topology of single symmetrical microstrip lines and consists of four sections of quarter-wavelength parallel coupling lines, seven sections of quarter-wavelength microstrip lines and seven PIN switches, wherein flexible reconfiguration of five band-pass filtering modes, namely a multi-transmission zero point high-isolation double-frequency band-pass mode, a three-frequency band-pass mode, a multi-zero point broadband band-pass mode, a double-side high-suppression double-frequency band-pass mode and a multi-zero point high-isolation double-frequency band-pass mode, is realized on the same hardware platform on the premise of not changing a main circuit frame by controlling the on-off states of the PIN switches.

Inventors

WU GANGXIONG
CAO YEWEI
SHI JIN
ZHANG WEI
JIANG RUIRUI

Assignees

南通大学

Dates

Publication Date: 20260508
Application Date: 20260326

Claims (10)

1. The five-mode reconfigurable microstrip line filter is characterized by comprising an input port 1, an output port 2, four sections of quarter-wavelength parallel coupling lines CL 1-CL 4, seven sections of quarter-wavelength microstrip lines ML 1-ML 7 and seven PIN switches P1-P7; The parallel coupling line CL1, the microstrip line ML2, the microstrip line ML3, the parallel coupling line CL2, the switch P2, the microstrip line ML6, the parallel coupling line CL4, the switch P5, the parallel coupling line CL3, the microstrip line ML5 and the switch P1 are sequentially connected in series to form a loop; The input port 1 is connected to the connection node of the parallel coupling line CL1 and the switch P1 through the microstrip line ML1, the output port 2 is connected to the connection node of the parallel coupling line CL2 and the switch P2 through the microstrip line ML4, the microstrip line ML7 with one open end is connected to the connection node of the microstrip line ML2 and the microstrip line ML3 through the switch P3, the connection node of the switch P5 and the parallel coupling line CL3 is also grounded through the switch P6, the parallel coupling line CL3 is also grounded through the switch P4, and the parallel coupling line CL4 is also grounded through the switch P7; By controlling the on and off states of PIN switches P1-P7, reconstruction switching of five band-pass filtering modes is realized under the same circuit topology.
2. The five-mode reconfigurable microstrip line filter of claim 1, wherein the parallel coupling line CL1 has a left lower end connected to the switch P1, a right upper end connected to the microstrip line ML2, a left upper end open-circuited with the right lower end, a left upper end connected to the microstrip line ML3, a right lower end connected to the switch P2, a left lower end open-circuited with the right upper end, a left upper end connected to the microstrip line ML5, a right lower end connected to the switch P5, a right upper end open-circuited, a right upper end connected to the microstrip line ML6, a left lower end connected to the switch P5, and a left upper end open-circuited.
3. The five-mode reconfigurable microstrip line filter of claim 2, wherein the lower left end of the parallel coupled line CL3 is grounded through a switch P4, and the lower right end of the parallel coupled line CL4 is grounded through a switch P7.
4. The five-mode reconfigurable microstrip filter of any of claims 1-3, wherein the five bandpass filtering modes include a multi-transmission zero dual-band bandpass mode, a tri-band bandpass mode, a wideband multi-pole bandpass mode, a double-sided high-rejection dual-band bandpass mode, and a passband-isolation enhancement dual-band bandpass mode.
5. The five-mode reconfigurable microstrip filter of claim 4, wherein in the multi-transmission-zero dual-band pass mode, the switches P1, P2, P5 are on and the switches P3, P4, P6, P7 are off.
6. The five-mode reconfigurable microstrip filter of claim 4, wherein in the three-band bandpass mode, the switches P1, P2, P5, P6 are on and the switches P3, P4, P7 are off.
7. The five-mode reconfigurable microstrip filter of claim 4, wherein in the wideband multi-pole bandpass filtering mode, switches P1, P2, P3 are turned off and switches P4-P7 are in a non-conductive state.
8. The five-mode reconfigurable microstrip filter of claim 4, wherein in the dual-side high rejection dual-band pass mode, switches P1, P2, P4, P7 are on and switches P3, P5, P6 are off.
9. The five-mode reconfigurable microstrip filter of claim 4, wherein in the inter-passband isolation enhancement mode dual-band-pass filtering mode, switches P1, P2, P3, P5 are on and switches P4, P6, P7 are off.
10. A five-mode reconfigurable microstrip filter according to any of claims 1-3, wherein the filter adopts a single symmetrical microstrip topology, an upper branch forms a basic resonant channel, a lower branch and an open branch ML7 participate in coupled resonance or ground loading through PIN switch control, and cross coupling of the upper and lower branches generates multiple transmission zeros.

Description

Five-mode reconfigurable microstrip line filter Technical Field The invention relates to the technical field of radio frequency communication electronics, in particular to a multimode reconfigurable microstrip line filter circuit. Background With the rapid development of wireless communication, satellite communication and radar detection technologies and the iterative evolution of a new generation of multi-frequency multi-system radio frequency front end, the filter is used as a core device of the radio frequency front end, and the performance requirement of the filter is gradually improved from the traditional single fixed frequency response to multi-frequency band adaptation, multi-functional integration, miniaturization and high integration degree. In the practical application scene of the limited circuit area, how to realize the flexible switching of the filter to the working mode and give consideration to the characteristics of low insertion loss, high return loss, excellent out-of-band rejection and steep transition band roll-off becomes the core research direction and key technical pain point in the field of reconfigurable filters. At present, in the prior art, a PIN diode, an MEMS switch or a variable capacitance element and other tunable elements are introduced to realize the reconstruction switching of the filter between band-pass/band-stop, broadband/double-frequency and other response modes. Although the technical path improves the spectrum adaptability of the system to a certain extent, a plurality of technical bottlenecks and defects still exist in engineering practical application, and the technical path is particularly characterized in that the circuit structure redundancy is high, and the integration promotion is limited. The existing multi-mode reconfigurable filter generally adopts a plurality of relatively independent resonance units or a plurality of sets of filter subcircuits to realize the switching of different modes, so that the redundancy of a circuit structure is obvious, the resource multiplexing rate is low, the miniaturization and high integration design of the filter are difficult to further realize, and the development requirement of high integration of the radio frequency front end cannot be met. Secondly, the performance difference among modes is obvious, and the comprehensive indexes are difficult to balance. Different working modes are often corresponding to independent coupling paths and resonance mechanisms, so that the filtering performance difference of each mode is larger, and the problems of larger insertion loss, insufficient return loss, weaker out-of-band rejection, steeper transition band roll-off and the like of partial modes are particularly solved, and the comprehensive equalization of the characteristics of low-loss pass band, high return loss, strong out-of-band rejection and steeper roll-off is difficult to realize. Thirdly, the number of the switchable modes is limited, and the unified topology is difficult to realize. The prior proposal can only realize single/few specific responses such as double-frequency band-pass, broadband band-pass or multi-frequency band-pass, and the like, has limited mode switching capability, and realizes flexible switching of a plurality of high-performance band-pass modes in the same topological structure, has great technical difficulty, and has insufficient construction capability for multi-zero point response, so that the challenge of simultaneously obtaining excellent frequency selectivity and deep stop band suppression under the multi-mode is presented. Particularly in a high-frequency application scene, the traditional design method cannot fully cooperate with the action mechanism of the coupling path and the resonance unit, so that the feasibility of flexibly realizing multiple response requirements such as double-frequency bandpass, triple-frequency bandpass, broadband bandpass and high-selectivity bandpass in a unified topology is further limited. In summary, it is difficult to simultaneously consider the structural integration level, the mode switching flexibility and the multimode performance balance of the filter in the prior art. Therefore, it is needed to propose a reconfigurable filter scheme based on a unified microstrip topology structure, so that the reconfigurable filter scheme can realize flexible switching of multiple filtering modes such as dual-frequency, tri-frequency, broadband, flat response and high selectivity on the premise of not remarkably increasing the circuit scale, has higher structural integration level and better out-of-band rejection capability, so as to solve a plurality of defects in the prior art, and meet the application requirements of a new generation of radio frequency front end. Disclosure of Invention Aiming at the prior art, the invention provides a five-mode reconfigurable microstrip line filter with high integration level, and unified integration and flexible switching of five