An absorptive low-pass filter with symmetrical structure

Abstract

The invention discloses an absorption type low-pass filter with a symmetrical structure, which belongs to the field of communication technology and is realized by adopting an LTCC substrate process. The filter comprises a low-pass filtering unit, a first dielectric material layer M1, a second dielectric material layer M2 and a third dielectric material layer M1 which are sequentially arranged from top to bottom, and solves the technical problem of bisecting an input signal to two output ends. The invention has the advantages of small size, high precision, good absorption of stopband signals, and can effectively reduce crosstalk in each transmission path, and has good application advantages in many electronic systems which are sensitive to reflected signals.

Description

Technical Field

[0001] The invention belongs to the technical field of communications, and in particular relates to an absorption type low-pass filter with a symmetrical structure. Background Art

[0002] With the rapid development of mobile communications, satellite communications and miniaturization of defense electronic systems, high performance, low cost and miniaturization have become the development direction of the microwave / RF field, and higher requirements have been put forward for the performance, size, reliability and cost of microwave devices. Nowadays, whether it is military radar, electronic detection, electronic countermeasures, etc., or civilian mobile phone communications, televisions, and remote controls, higher requirements have been put forward for the microwave devices they carry. Among these microwave devices, filters occupy a very important position in the RF front end of communications and wireless systems. At present, most of the filters we use are reflective filters, that is, they reflect unwanted signals back to the input end through the stop band. In many actual systems, the signal reflected back to the input port by the reflective filter will have a certain impact on the performance of the entire system. Therefore, the concept of non-reflective filters is proposed. Summary of the invention

[0003] The purpose of the present invention is to provide an absorptive low-pass filter with a symmetrical structure, which solves the technical problem of dividing an input signal into two equal parts at an output end.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] An absorption type low-pass filter with a symmetrical structure, comprising a low-pass filtering unit, a first dielectric material layer M1, a second dielectric material layer M2 and a third dielectric material layer M3 arranged in sequence from top to bottom;

[0006] The low-pass filter unit has an input port Pin on the left side, an output port Pout on the right side, a ground port P3 on the front side, and a ground port P4 on the rear side;

[0007] The low-pass filter unit includes a symmetrical series resonant unit A1, a symmetrical series resonant unit A2, a symmetrical parallel resonant unit B1, a symmetrical parallel resonant unit B2 and a resistor R, wherein the resistor R is arranged at the center of the low-pass filter unit, one end of the resistor R is connected to the input port Pin, and the other end is connected to the output port Pout;

[0008] A symmetrical series resonant unit A1 and a symmetrical series resonant unit A2 are provided on the rear side of the resistor R from left to right, and a symmetrical parallel resonant unit B1 and a symmetrical parallel resonant unit B2 are provided on the front side of the resistor R from left to right.

[0009] The symmetrical parallel resonant unit B1 and the symmetrical parallel resonant unit B2 are both connected to the ground port P4;

[0010] The low-pass filter unit is arranged in the second dielectric material layer M2;

[0011] The resistance value of the resistor R is set by the resistor paste material.

[0012] Preferably, the symmetrical series resonant unit A1, the symmetrical series resonant unit A2, the symmetrical parallel resonant unit B1 and the symmetrical parallel resonant unit B2 are all provided with a spiral structure inductor;

[0013] The symmetrical series resonant unit A1, the symmetrical series resonant unit A2, the symmetrical parallel resonant unit B1 and the symmetrical parallel resonant unit B2 are also provided with double-layer capacitors. Preferably, the first dielectric material layer M1 and the third dielectric material layer M3 are both made of low dielectric constant materials, and the second dielectric material layer M2 is made of high dielectric constant material.

[0014] Preferably, the input port Pin and the output port Pout are both surface mounted 50 ohm impedance output ports.

[0015] Preferably, the inductance of the symmetrical series resonant unit A1 and the inductance of the symmetrical series resonant unit A2 are both in the same layer, and the inductance of the symmetrical parallel resonant unit B1 and the inductance of the symmetrical parallel resonant unit B2 are both in the same layer.

[0016] Preferably, a ground plate GND is further provided, and both the ground port P3 and the ground port P4 are connected to the ground plate GND.

[0017] The absorptive low-pass filter with a symmetrical structure described in the present invention solves the technical problem of dividing the input signal into two equal parts at the output end. The present invention has the advantages of small size, high precision, good absorption of stopband signals, and can effectively reduce crosstalk in each transmission path. It has good application advantages in many electronic systems that are sensitive to reflected signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a low-pass filter unit of the present invention;

[0019] Figure 2 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 3 It is the output characteristic curve of the present invention. DETAILED DESCRIPTION

[0021] like Figure 1-Figure 3 The absorptive low-pass filter of a symmetrical structure shown comprises a low-pass filtering unit, a first dielectric material layer M1, a second dielectric material layer M2 and a third dielectric material layer M3 arranged in sequence from top to bottom;

[0022] The low-pass filter unit has an input port Pin on the left side, an output port Pout on the right side, a ground port P3 on the front side, and a ground port P4 on the rear side;

[0023] The low-pass filter unit includes a symmetrical series resonant unit A1, a symmetrical series resonant unit A2, a symmetrical parallel resonant unit B1, a symmetrical parallel resonant unit B2 and a resistor R, wherein the resistor R is arranged at the center of the low-pass filter unit, one end of the resistor R is connected to the input port Pin, and the other end is connected to the output port Pout;

[0024] A symmetrical series resonance unit A1 and a symmetrical series resonance unit A2 are provided on the back side of the resistor R from left to right, and a symmetrical parallel resonance unit B1 and a symmetrical parallel resonance unit B2 are provided on the front side of the resistor R from left to right; the symmetrical parallel resonance unit B1 and the symmetrical parallel resonance unit B2 are both connected to the ground port P4; the low-pass filter unit is arranged in the second dielectric material layer M2; the resistance value of the resistor R is set by the resistor paste material.

[0025] Preferably, the symmetrical series resonant unit A1, the symmetrical series resonant unit A2, the symmetrical parallel resonant unit B1 and the symmetrical parallel resonant unit B2 are all provided with a spiral structure inductor;

[0026] The symmetrical series resonant unit A1, the symmetrical series resonant unit A2, the symmetrical parallel resonant unit B1 and the symmetrical parallel resonant unit B2 are also provided with double-layer capacitors. Preferably, the first dielectric material layer M1 and the third dielectric material layer M3 are both made of low dielectric constant materials, and the second dielectric material layer M2 is made of high dielectric constant material.

[0027] Preferably, the input port Pin and the output port Pout are both surface mounted 50 ohm impedance output ports.

[0028] Preferably, the inductance of the symmetrical series resonant unit A1 and the inductance of the symmetrical series resonant unit A2 are both in the same layer, and the inductance of the symmetrical parallel resonant unit B1 and the inductance of the symmetrical parallel resonant unit B2 are both in the same layer.

[0029] Preferably, a ground plate GND is further provided, and both the ground port P3 and the ground port P4 are connected to the ground plate GND.

[0030] When in use, the source signal is input from the input port Pin, and is output from the output port Pout through the resistor R. The symmetrical series resonant unit A1, the symmetrical series resonant unit A2, the symmetrical parallel resonant unit B1, and the symmetrical parallel resonant unit B2 are distributed on the back and front sides of the resistor R, and the source signal is low-pass filtered to divide the input signal into two equal parts at the output end. The present invention adopts a specific symmetrical three-dimensional integrated structure and is implemented using LTCC substrate process technology. The absorption low-pass filter in the present invention is small in size and only

[0031] 2.6mm*2.6mm*1mm, small size, light weight, high reliability, excellent electrical performance, high yield rate, good batch consistency, stable temperature performance, good stopband signal absorption, new symmetrical structure absorption low-pass filter, its performance can be seen from Figure 2 It can be seen that its cutoff frequency is 4GHz and the return loss is good. This filter is small in size, high in precision, and has good stopband signal absorption. It can be widely used in a variety of systems that are sensitive to reflected signals.

[0032] The absorptive low-pass filter with a symmetrical structure described in the present invention solves the technical problem of dividing the input signal into two equal parts at the output end. The present invention has the advantages of small size, high precision, good absorption of stopband signals, and can effectively reduce crosstalk in each transmission path. It has good application advantages in many electronic systems that are sensitive to reflected signals.

Claims

1. An absorptive low-pass filter with a symmetrical structure, characterized in that: It includes a low-pass filter unit, a first dielectric material layer M1, a second dielectric material layer M2 and a third dielectric material layer M3 which are sequentially arranged from top to bottom; the low-pass filter unit is provided with an input port Pin on the left side, an output port Pout on the right side, a ground port P3 on the front side and a ground port P4 on the back side; the low-pass filter unit includes a symmetrical series resonance unit A1, a symmetrical series resonance unit A2, a symmetrical parallel resonance unit B1, a symmetrical parallel resonance unit B2 and a resistor R, the resistor R is arranged at the center of the low-pass filter unit, one end of the resistor R is connected to the input port Pin, and the other end is connected to the output port Pout; A symmetrical series resonant unit A1 and a symmetrical series resonant unit A2 are provided on the rear side of the resistor R from left to right, and a symmetrical parallel resonant unit B1 and a symmetrical parallel resonant unit B2 are provided on the front side of the resistor R from left to right. The symmetrical parallel resonant unit B1 and the symmetrical parallel resonant unit B2 are both connected to the ground port P4; the low-pass filter unit is arranged in the second dielectric material layer M2; the resistance value of the resistor R is set by the resistor paste material; The symmetrical series resonant unit A1, the symmetrical series resonant unit A2, the symmetrical parallel resonant unit B1 and the symmetrical parallel resonant unit B2 are all provided with a spiral structure inductor; The symmetrical series resonant unit A1, the symmetrical series resonant unit A2, the symmetrical parallel resonant unit B1 and the symmetrical parallel resonant unit B2 are also provided with double-layer capacitors; the first dielectric material layer M1 and the third dielectric material layer M3 are both made of low dielectric constant materials, and the second dielectric material layer M2 is a high dielectric constant material; The input port Pin and the output port Pout are both surface mounted 50 ohm impedance output ports; The inductance of the symmetrical series resonant unit A1 and the inductance of the symmetrical series resonant unit A2 are both on the same layer, and the inductance of the symmetrical parallel resonant unit B1 and the inductance of the symmetrical parallel resonant unit B2 are both on the same layer.

2. The absorptive low-pass filter of a symmetrical structure as claimed in claim 1, characterized in that: A ground plate GND is also provided, and the ground port P3 and the ground port P4 are both connected to the ground plate GND.

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