Tunable band-pass filter

Abstract

The embodiment of the invention discloses a tunable band-pass filter, which comprises a substrate, a metal layer, a plurality of external electrodes and a plurality of high-impedance offset lines, wherein the metal layer covers the substrate; the metal layer is symmetrically provided with two filter units at an interval; each filter unit comprises a gap line group and a plurality of MEMS switches; each gap line group comprises an open gap ring, a first gap line, a second gap line and a plurality of sub-gap lines, so that the functions of resonators are achieved through the open gap rings and the plurality of sub-gap lines arranged in the open gap rings; and signals are transmitted along gaps of the two gap line groups, so that the band-pass filtering function is achieved. The MEMS switches are integrated on the corresponding sub-gap lines; and switch beams are controlled to be in contact with corresponding dielectric layers below the switch beams or to be in a free state through the external electrodes, so that adjustment of the center frequency of the filter is achieved through controlling two states of each MEMS switch. By the tunable band-pass filter, miniaturization of the tunable band-pass filter is convenient to achieve, the adjustment accuracy on the center frequency is improved and the working reliability of the filter is improved.

Description

technical field [0001] The invention relates to the technical field of radio frequency micro-electromechanical systems, in particular to an adjustable band-pass filter. Background technique [0002] A band-pass filter is a device that allows waves of a specific frequency band to pass while blocking other frequency bands. The adjustable band-pass filter refers to a band-pass filter with an adjustable center frequency, which can replace multiple non-adjustable band-pass filters, greatly reducing system cost and device volume. Since the 1990s, Radio Frequency Micro electromechanical system (RF MEMS for short) is one of the important application fields of MEMS technology, widely used in wireless communication. The coplanar waveguide tunable bandpass filter based on MEMS technology has the advantages of low cost, small size and easy integration, and is a research hotspot in the field of international communication. [0003] The traditional MEMS coplanar waveguide bandpass tunab...

AI Technical Summary

Problems solved by technology

[0003] The traditional MEMS coplanar waveguide bandpass tunable filter is based on the principle of MEMS switches controlling the equivalent electrical length transformation of transmission lines. It is realized by cascading multiple resonators and loading MEMS switches on each resonator. Such a structure setting, is not conducive to the miniaturization of the filter

Moreover, the existing filters mainly change the resonant frequency of the resonator by changing the height of the MEMS switch. Since the adjustment of the height of the MEMS switch is realized through the deformation and positioning of the switch beam, after multiple adjustments, the switch beam will be fatigued, and the height adjustment cannot be accurate. Positioning, resulting in the reduction of height adjustment accuracy, resulting in the adjustment accuracy of the center frequency of the filter gradually decreasing with the increase of the number of uses, and the reliability is reduced

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