Miniaturized helical surface mountable bandpass filter based on multilayer PCB structure

Abstract

The invention discloses a miniaturized spiral-shaped surface-mountable bandpass filter based on a multilayer PCB structure, which includes four layers of dielectric substrates, five layers of metal copper layers, three layers of prepreg adhesive layers, and four quarter-wavelength filters. Shorted spiral resonator, spiral coupling window, through metallized vias and coplanar waveguide feed port. The invention utilizes multi-layer PCB lamination technology to design a quarter-wavelength short-circuit spiral resonator in a metal shielding cavity, which are embedded in each other in the horizontal direction and stacked in the vertical direction, which is miniaturized, compact and easy to design. , surface mountable, high selectivity, high out-of-band rejection, low loss, and high power capacity, are conducive to the application of scenarios requiring small size and high performance, such as base station systems and handheld devices.

Description

technical field [0001] The invention relates to the technical field of band-pass filters, in particular to a miniaturized spiral-shaped surface-mountable band-pass filter based on a multilayer PCB structure. Background technique [0002] As an indispensable and important device in radio frequency circuits and wireless communication systems, filters determine the performance and quality of the entire microwave system. With the comprehensive advancement of communication technologies represented by 5G, there is an urgent need for miniaturized and high-performance bandpass filters below 6GHz that meet the N78 frequency band (3300MHz~3800MHz). As an important branch of filters, bandpass filters are the main components of signal selection and interference suppression in microwave systems, and are widely used in mobile communications and integrated circuits. [0003] Currently commonly used bandpass filters are roughly divided into lumped element bandpass filters, metal cavity ban...

AI Technical Summary

Problems solved by technology

[0004] As far as the commonly used lumped element bandpass filter is concerned, due to the limitation of the distributed parameters of the lumped element capacitance and inductance at high frequencies, the capacitance value and inductance value cannot maintain the nominal value and are not easy to control. Lumped parameter filters are not easy to be designed at high frequencies, etc.

[0005] As far as the commonly used metal cavity bandpass filter is concerned, due to the structure and production limitations of the metal cavity, there are disadvantages such as large volume and heavy weight. At the same time, the filter has a single structure and has disadvantages such as inflexible design.

[0006] As far as the commonly used microstrip bandpass filter is concerned, due to the limitation of the structure of the microstrip line, the open space structure prevents the electric field at the edge of the microstrip from being completely bound in the dielectric substrate, and some energy radiates to the surrounding open space. Among them, there are disadvantages such as relatively large losses; at the same time, limited by the lack of corresponding shielding structures, the energy radiated by the microstrip bandpass filter is likely to cause interference to other circuit components in the same system, and is also susceptible to interference from other electromagnetic energy , there is a disadvantage of relatively weak electromagnetic compatibility

[0007] As far as the currently commonly used substrate-integrated waveguide bandpass filter is concerned, due to the limitation of the substrate-integrated waveguide transmission mode, there is a disadvantage that electromagnetic signals below the cut-off frequency of the waveguide cannot be transmitted in the substrate-integrated waveguide; at the same time, it is limited by There are limitations in the principle of substrate-integrated waveguide resonance, and there are disadvantages such as relatively large volume

[0008] As far as the currently commonly used low-temperature co-fired ceramic technology bandpass filter is concerned, limited by the processing technology, LTCC needs to use ceramic materials with high relative permittivity, and at the same time adopt high-density integration, which has disadvantages such as high cost

[0009] As far as the commonly used surface acoustic wave bandpass filter is concerned, the insertion loss of the surface acoustic wave filter is generally relatively large, and it cannot be well integrated into the circuit; and it is generally only suitable for communication systems below 2GHz, and it is difficult to In the case of high power, it is applied to high frequency and other disadvantages

[0010] To sum up, the currently commonly used lumped element bandpass filter has the disadvantages that it is difficult to apply to high frequency; the metal cavity bandpass filter is limited by the metal structure, and has the disadvantages of large volume, heavy weight, and inflexible design. ; The microstrip bandpass filter is in an open space, which has the disadvantages of large radiation loss, easy interference with other circuit components and interference from other components; the substrate integrated waveguide bandpass filter is limited by the principle of resonance, and has relatively large Larger disadvantages; low-temperature co-fired ceramic technology band-pass filters are limited by processing technology and have disadvantages such as high cost; surface acoustic wave band-pass filters have relatively large insertion loss and are difficult to apply to high-frequency and high-power applications. shortcoming

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