阅读说明：本技术 一种射频滤波电路 (Radio frequency filter circuit ) 是由 胡孝伟 代文亮 付董董 于 2020-06-22 设计创作，主要内容包括：本发明的一种射频滤波电路,属于射频滤波技术领域。包括端口一和端口二,端口一和端口二之间连接有主分支MB,该主分支MB上设有两个向下延伸的分支,所述两个向下延伸的分支分别设有滤波器REA和滤波器REB,所述滤波器REA与端口一之间连接有匹配网络MNA,所述滤波器REB与端口B之间连接有匹配网络MNB。匹配网络MNA可以提供在端口一处阻抗匹配匹配网络MNB可以提供在端口二处阻抗匹配,本发明的射频滤波电路不仅结构简单、尺寸小且性能更佳。(The invention discloses a radio frequency filter circuit, and belongs to the technical field of radio frequency filtering. The filter comprises a first port and a second port, a main branch MB is connected between the first port and the second port, two downward extending branches are arranged on the main branch MB, a filter REA and a filter REB are respectively arranged on the two downward extending branches, a matching network MNA is connected between the filter REA and the first port, and a matching network MNB is connected between the filter REB and the second port. The matching network MNA can provide the impedance matching at the first port and the matching network MNB can provide the impedance matching at the second port.)

1. A radio frequency filter circuit, characterized by: the filter comprises a first port and a second port, a main branch MB is connected between the first port and the second port, two downward extending branches are arranged on the main branch MB, a filter REA and a filter REB are respectively arranged on the two downward extending branches, a matching network MNA is connected between the filter REA and the first port, and a matching network MNB is connected between the filter REB and the second port.

2. A radio frequency filter circuit according to claim 1, wherein: also included is a notch network NWA coupled to the main branch MB.

3. A radio frequency filter circuit according to claim 1, wherein: the filter MNA is a parallel resonator, and one or more of the inductance element LA, the capacitance element CA, and the acoustic wave resonator are connected in parallel, and the one or more of the inductance element LA, the capacitance element CA, and the acoustic wave resonator are connected in parallel with respect to the main branch MB.

4. A radio frequency filter circuit according to claim 1, wherein: the filter MNB is a parallel resonator, and one or more of the inductive element LB, the capacitive element CB, and the acoustic resonator are connected in parallel, and the one or more of the inductive element LB, the capacitive element CB, and the acoustic resonator are connected in parallel with respect to the main branch MB.

5. A radio frequency filter circuit according to claim 2, wherein: the trap network NWA is a trap network provided with several capacitive elements CN connected in parallel to each other, each capacitive element CN being coupled between the resonator REA and the resonator REB.

6. A radio frequency filter circuit according to claim 2, wherein: the trap network NWA is a trap network provided with a plurality of acoustic wave resonators YN connected in parallel, and each acoustic wave resonator YN is coupled between a resonator REA and a resonator REB.

7. A radio frequency filter circuit according to claim 2, wherein: the trap network NWA is a trap network provided with a plurality of acoustic wave resonators YN and a plurality of capacitance elements CN connected in parallel, and each acoustic wave resonator YN and each capacitance element CN are coupled between the resonator REA and the resonator REB.

Technical Field

The invention belongs to the technical field of radio frequency filtering, and particularly relates to a radio frequency filtering circuit.

Background

Rf filters are widely used in the transmit-receive chain of rf terminals to allow signals of a specific frequency or band to pass through while filtering out unwanted interference or spurious signals. The filter circuit consists of a plurality of resonance units which are connected in different circuit forms to provide a filter circuit with a certain bandwidth.

Radio Frequency (RF) filter circuits typically include a plurality of RF filter chains, each chain providing a different passband tuned within a different RF communication band so that RF signals operating within the different RF communication band can be transmitted to the appropriate downstream circuitry. To prevent adjacent RF communication bands from interfering with each other (especially when the RF communication bands are close to each other), it is often necessary to increase the roll-off of the passband to increase out-of-band rejection. This is typically accomplished by using notch filtering components created near the passband to increase the roll-off and out-of-band rejection of the passband. For the passband in the high frequency range, the roll-off provided by the LC filter is generally insufficient to provide adequate isolation between the near (about 100MHz or less) passband and the high frequency range (frequency range with frequencies greater than 1 GHz). It is therefore desirable to provide a radio frequency filter circuit that is capable of increasing out-of-band rejection in the high frequency range.

Filters constructed from discrete components have not been able to meet the performance, size and cost requirements of today's products. However, acoustic wave filters (e.g., SAW and BAW) support the selection of corresponding filters in a monolithic like complete package. The acoustic filter can operate at high and low frequencies (up to 6GHz), is one of the smallest filters physically, and has the best performance and cost point to meet the complex filtering requirements.

The LC filter can have excellent linear phase characteristics (group delay characteristics), but it is at the expense of selectivity, and has large volume, poor stability, and troublesome debugging.

The SAW surface acoustic wave element mainly uses the piezoelectric property of piezoelectric material, uses the input and output transducers to convert the input signal of electric wave into mechanical energy, and converts the mechanical energy into electric signal after processing, so as to achieve the goal of filtering unnecessary signal and noise and raising the receiving quality. Acoustic surface filters and acoustic surface resonators are widely used in various wireless communication systems. The main function is to filter out the noise, and the installation is simpler and the volume is smaller than the traditional LC filter.

Another common new type of rf filter is a bulk acoustic wave filter BAW, which differs from a SAW filter in that the acoustic waves in the BAW filter propagate vertically. In BAW resonators using quartz crystal as the substrate, metal embedded on both sides of the top and bottom of the quartz substrate excites the acoustic wave, which bounces from the top surface to the bottom to form a standing acoustic wave. While slab thickness and electrode quality determine the resonant frequency.

Disclosure of Invention

1. Technical problem to be solved by the invention

The invention aims to solve the problems of complex structure and poor performance of the conventional radio frequency filter circuit.

2. Technical scheme

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the invention relates to a radio frequency filter circuit, which comprises a first port and a second port, wherein a main branch MB is connected between the first port and the second port, two downward extending branches are arranged on the main branch MB, a filter REA and a filter REB are respectively arranged on the two downward extending branches, a matching network MNA is connected between the filter REA and the first port, and a matching network MNB is connected between the filter REB and the second port.

Preferably, a notch network NWA is also included, coupled to the main branch MB.

Preferably, the filter MNA is a parallel resonator, and one or more of the inductive element LA, the capacitive element CA, and the acoustic wave resonator are connected in parallel, and the one or more of the inductive element LA, the capacitive element CA, and the acoustic wave resonator are connected in parallel with respect to the main branch MB.

Preferably, the filter MNB is a parallel resonator, and one or more of the inductive element LB, the capacitive element CB, and the acoustic resonator are connected in parallel, and the one or more of the inductive element LB, the capacitive element CB, and the acoustic resonator are connected in parallel with respect to the main branch MB.

Preferably, the trap network NWA is a trap network provided with several capacitive elements CN connected in parallel to each other, each capacitive element CN being coupled between the resonator REA and the resonator REB.

Preferably, the notch network NWA is a notch network provided with a plurality of acoustic wave resonators YN connected in parallel, and each acoustic wave resonator YN is coupled between the resonator REA and the resonator REB.

Preferably, the trap network NWA is a trap network provided with a plurality of acoustic wave resonators YN and a plurality of capacitance elements CN connected in parallel with each other, and each acoustic wave resonator YN and each capacitance element CN are coupled between the resonator REA and the resonator REB.

3. Advantageous effects

Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:

the invention relates to a radio frequency filter circuit, which comprises a first port and a second port, wherein a main branch MB is connected between the first port and the second port, two downward extending branches are arranged on the main branch MB, a filter REA and a filter REB are respectively arranged on the two downward extending branches, a matching network MNA is connected between the filter REA and the first port, and a matching network MNB is connected between the filter REB and the second port. The matching network MNA can provide the impedance matching at the first port and the matching network MNB can provide the impedance matching at the second port.

Drawings

FIG. 1 is a schematic diagram of an RF filter circuit according to the present invention;

FIG. 2 is a schematic diagram of the filter REA according to the present invention;

FIG. 3 is a schematic diagram of the structure of the filter REB of the present invention;

FIG. 4 is a schematic structural diagram of a notch network NWA of the present embodiment 1;

FIG. 5 is a schematic diagram of a structure of a notch network NWA in the present embodiment 2;

fig. 6 is a schematic diagram of the structure of the notch network NWA in the present embodiment 3.

Detailed Description

In order to facilitate an understanding of the invention, the invention will now be described more fully hereinafter with reference to the accompanying drawings, in which several embodiments of the invention are shown, but which may be embodied in many different forms and are not limited to the embodiments described herein, but rather are provided for the purpose of providing a more thorough disclosure of the invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present; when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present; the terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention; as used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.