WO2015074277A1

WO2015074277A1 - Power device and micro-strip filter thereof

Info

Publication number: WO2015074277A1
Application number: PCT/CN2013/087785
Authority: WO
Inventors: 陈凌伟; 张静磊
Original assignee: 海能达通信股份有限公司
Priority date: 2013-11-25
Filing date: 2013-11-25
Publication date: 2015-05-28

Abstract

A power device and micro-strip filter thereof. The micro-strip filter comprises at least two units, and each unit comprises a second micro-strip line, a third micro-strip line and a first capacitor, wherein the second micro-strip line is provided with a first end and second end, one end of the first capacitor being connected to the second end of the second micro-strip line, and the other end being connected to the reference ground; one end of the third micro-strip line is connected to the second end of the second micro-strip line, and the other end is opened or connected to the reference ground; and every two adjacent units are symmetrically connected through a first micro-strip line.

Description

Power device and microstrip filter thereof

Technical field

The present invention relates to the field of communications, and in particular, to a power device and a microstrip filter thereof.

Background technique

Filters are a very important device in microwave systems. The filter mainly has two types of LC filter and microstrip filter. Among them, the LC filter is composed of high-power inductor and capacitor. As shown in Fig. 1, the LC filter is the most widely used filter structure at this stage; The microstrip filter consists of a microstrip line and a microstrip stub, as shown in Figure 2.

At this stage, the high-power field with a working frequency of less than 500 MHz mainly uses an LC filter, which has the characteristics of simple design and small size. However, the inductance is poorly consistent due to factors such as self-processing accuracy, welding, and deformation of the force. Moreover, high-power inductors generally have higher costs, which is not conducive to improving product competitiveness. In addition, the high-power inductor used in the LC filter has a high height, a large number of magnetic lines are not closed, and is greatly affected by the surrounding magnetic field environment, which brings many difficulties to the design of the shielding cavity and the product structure. For the microstrip line filter, it is rarely used for power devices with a working frequency lower than 500 MHz, mainly because the microstrip line length is required to be very long when the frequency is low, and the area occupied by the PCB board is very large, which is disadvantageous for productization.

Summary of the invention

The technical problem to be solved by the present invention is to provide a power device that occupies a small PCB board area, low cost, and simple structural design, and has the advantages of occupying a large PCB board area, high cost, and complicated structure design. Microstrip filter.

The technical solution adopted by the present invention to solve the technical problem thereof is to construct a microstrip filter including at least two units.

Each unit includes a second microstrip line, a third microstrip line, and a first capacitor, wherein the second microstrip line has a first end and a second end, and one end of the first capacitor is coupled to the second micro a second end of the line with the other end connected to the ground; one end of the third microstrip line is connected to the second end of the second microstrip line, and the other end is open or grounded;

The adjacent two units are connected symmetrically by a first microstrip line, and the symmetric connection is: the first ends of the second microstrip lines of the adjacent two units are connected by the first microstrip line, or adjacent The second ends of the second microstrip lines of the two units are connected by the first microstrip line.

In the microstrip filter of the present invention, each of the cells further includes a second capacitor, the first end of the second capacitor is connected to the first end of the second microstrip line, and the second capacitor is The second terminal is connected to the ground.

In the microstrip filter of the present invention, each of the cells further includes a third capacitor connected in parallel at both ends of the second microstrip line.

In the microstrip filter of the present invention, each unit further includes a second capacitor and a third capacitor, and a first end of the second capacitor is connected to the first end of the second microstrip line, The second end of the second capacitor is connected to the reference ground, and the third capacitor is connected in parallel at both ends of the second microstrip line.

In the microstrip filter of the present invention, the width of the third microstrip line is smaller than the width of the first microstrip line and the second microstrip line.

The invention also constructs a power device comprising a PCB board and a load and a filter disposed on the PCB, the filter being the microstrip filter described above.

In the power device of the present invention, the PCB board is a multi-layer PCB board, and the first microstrip line and the second microstrip line are disposed on a first layer of the multi-layer PCB board. The third microstrip line is disposed on a second layer of the multilayer PCB board.

In the power device of the present invention, the third microstrip line is arranged in an S shape or a disk shape on the PCB board.

In the power device of the present invention, the impedances of the first microstrip line and the second microstrip line respectively match the impedance of the load.

DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

1 is a circuit diagram of a prior art filter;

2 is a circuit diagram of another filter of the prior art;

Figure 3 is a circuit diagram of Embodiment 1 of the microstrip filter of the present invention;

4 is a circuit diagram of Embodiment 2 of the microstrip filter of the present invention;

FIG. 5 is a partial schematic diagram of Embodiment 1 of a power device according to the present invention.

detailed description

Figure 3 is the present invention Microcircuit Example The circuit diagram of the first embodiment, the microstrip filter includes two

adjacent cells

10, 20, and the two

cells

10, 20 are symmetrically connected by a first microstrip line L2. The unit 10 includes a second microstrip line L1, a third microstrip line L4, and a first capacitor C3. Moreover, the second microstrip line L1 has a first end and a second end, and the first capacitor C3 is connected to the second micro. Between the second end of the strip line L1 and the reference ground, one end of the third microstrip line L4 is connected to the second end of the second microstrip line L1, and the other end is open. Correspondingly, the unit 20 includes a second microstrip line L3, a third microstrip line L5, and a first capacitor C4. Moreover, the second microstrip line L3 has a first end and a second end, and the first capacitor C4 is connected to the second Between the second end of the microstrip line L3 and the reference ground, the first end of the third microstrip line L5 is connected to the second end of the second microstrip line L3, and the other end is open. Moreover, the unit 10 and the unit 20 are symmetrically connected by the first microstrip line L2 such that the second end of the second microstrip line L1 of the unit 10 is connected to the second end of the second microstrip line L3 of the unit 20. In the microstrip filter of this embodiment, the third microstrip line L4, L5 affects the lowest frequency of the pass band of the filter. Within a certain range, the longer the length of the third microstrip line L4, L5, the higher the impedance. The lowest frequency is also lower. The first microstrip line L2 affects the maximum bandwidth of the filter passband. Within a certain range, the longer the first microstrip line L2 is, the narrower the bandwidth is. The first capacitors C3, C4 affect the highest frequency of the filter passband, and the larger the first capacitors C3, C4, the smaller the maximum frequency allowed to pass.

In the above embodiment, the microstrip filter is composed of a microstrip line and a capacitor. Compared with the LC filter in the prior art, the microstrip line has high processing precision, and there is no influence of soldering or deformation, and the product consistency is high. Moreover, since the cost of the inductor is eliminated, the cost is correspondingly reduced. At the same time, because there is no higher device, the space requirement is small, the design of the shielding cavity and the product structure is simple, which is beneficial to improve the quality of the product. Compared with the microstrip filter in the prior art, the length of the microstrip line can be reduced due to the addition of the capacitor, thereby saving the area occupied by the PCB.

Finally, it should be noted that although only two units are shown in the figure, it should be understood that in other embodiments of the invention, the number of units may be greater than two, as long as the adjacent two units are symmetrically connected, ie a first end of the second microstrip line of the adjacent two units is connected by the first microstrip line, or a second end of the second microstrip line of the adjacent two units passes the first microstrip line Connected. . In addition, the parameters of the first microstrip line connected between each adjacent two units are the same, and the parameters of the corresponding devices in each unit are the same, for example, the parameters of the second microstrip line in each unit are the same, each The parameters of the third microstrip line in the unit are the same, and the parameters of the first capacitor in each unit are the same.

4 is a circuit diagram of a second embodiment of the microstrip filter of the present invention. Compared with the first embodiment shown in FIG. 3, the embodiment has the following differences:

In the

units

10, 20, the third microstrip lines L4, L5 are all connected to the reference ground, which is advantageous for heat dissipation. The specific reason is that if the reference ground is not connected, heat can only be transmitted through the dielectric layer, and the reference ground means It can be connected to other metals (such as heat sinks), and the thermal conductivity of the dielectric layer is very small, and the thermal conductivity of the metal is very large. Therefore, the heat dissipation effect after grounding is better.

The unit 10 further includes a second capacitor C1. The unit 20 further includes a second capacitor C6. Moreover, one end of the second capacitor C1 is connected to the first end of the second microstrip line L1, and the second end of the second capacitor C1 is connected to the ground. One end of the second capacitor C6 is connected to the first end of the second microstrip line L3, and the second end of the second capacitor C6 is connected to the ground. In this embodiment, the second capacitors C1, C6 function to regulate the input reflection coefficient (i.e., return loss) and out-of-band distal suppression.

The unit 10 further includes a third capacitor C2, the unit 20 further includes a third capacitor C5, and the third capacitor C2 is connected in parallel across the second microstrip line L1, and the third capacitor C5 is connected in parallel to the second microstrip line L3. end. In this embodiment, the third capacitor C2 and the second microstrip line L1 together with the third capacitor C5 and the second microstrip line L3 form a band rejection filter, which can increase the suppression capability of a certain frequency band as needed, for example, if The resonance point of the third capacitor and the second microstrip line parallel circuit is near the second harmonic, thereby increasing the ability to suppress the second harmonic.

In the

units

10, 20, the width of the third microstrip line L4, L5 is smaller than the width of the first microstrip line L2 and the second microstrip line L1, L3. This can further save the space occupied by the PCB, because the first microstrip line L2 and the second microstrip line L1, L3 are main signal paths, for example, a 60W radio frequency signal passes, the line is too fine and the loss is too large, and the third micro The main signals of the strip lines L4 and L5 do not pass, but only function as filtering, so the width thereof may be smaller than the widths of the first microstrip line L2 and the second microstrip lines L1, L3.

5 is a partial schematic view of a first embodiment of a power device according to the present invention, the power device including a PCB board (not shown) and a load (not shown) disposed on the PCB board and a microstrip filter, the microstrip filter The circuit structure can be referred to as described above, and in this embodiment, the third microstrip lines L4, L5 are arranged in an S shape on the PCB board, which can save space for occupying the PCB. Of course, in other embodiments, the third microstrip lines L4, L5 may also be arranged in a disc-shaped arrangement or in other irregular manners. Accordingly, such an arrangement is equally applicable to the first microstrip line L2 and The second microstrip lines L1, L3. In this embodiment, the filter has a passband frequency of 400 MHz to 530 MHz and a stop band of 800 MHz to 4 GHz for suppressing harmonics generated by the power amplifier in the power device. If the first microstrip line L2 has a width of 80 mils and a length of 1250 mils, the second microstrip lines L1, L3 have a width of 80 mils and a length of 900 mils. The width of the third microstrip line L4, L5 is 40 mil, the length is 1300 mil, the first capacitor C3, C4 selects 251R15S120JV4S, the second capacitor C1, C6 selects 251R15S6R8CV4S, and the third capacitor C2, C5 selects 251R15S7R5CV4S. The microstrip filter of this embodiment has an area of 16 mm * 27 mm on the PCB, allowing 50 W of power to continue to pass. The above is only an example of the present invention. In practical applications, the minimum width of the first microstrip line L2 and the second microstrip line L1, L3 is determined by the power required to be passed. If the power is small, such as 1 W, then 10 The width of the mil is sufficient; if the power is relatively large, such as 50W, it needs at least 60mil. The length of the second microstrip line L1, L3 is preferably as small as possible from the occupied PCB area, and its length is as short as possible, but not less than 1/12 of the lowest wavelength at which the signal suppression is required. For example, if you want to suppress the signal frequency to 600MHz and the dielectric constant is 4.6, the length must not be lower than 900mil. The length of the first microstrip line L2 is determined according to the required passband width. The longer L2 is, the narrower the passband width is, and the passband input reflection coefficient is better.

Preferably, if the PCB board is a multilayer PCB board, the third microstrip lines L4, L5 may be disposed on different layers of the PCB board with the first microstrip line L2 and the second microstrip line L1, L3. For example, the first microstrip line L2 and the second microstrip line L1, L3 are disposed on the first layer of the multilayer PCB board, and the third microstrip line L4, L5 is disposed on the second layer of the multilayer PCB board. The first microstrip line L2 and the second microstrip line L1, L3 are disposed in the first layer because they are connected with more capacitive components (for example, the first capacitors C3, C4, the second capacitors C1, C6, etc.), This facilitates the connection of the capacitive device to the microstrip line. If the first microstrip line L2 and the second microstrip line L1, L3 are disposed in the second layer, the via hole is required, and the performance is degraded. Moreover, due to the impedance of the microstrip line and its distance from the reference ground, the first microstrip line L2 and the second microstrip line L1, L3 are typically 50 ohms of characteristic impedance, which is placed in the first layer and can be distance referenced. The ground (for example, set on the sixth layer of the PCB) is farther away, and the line width will be wider, allowing the power to pass through to be larger. The third microstrip line L4, L5 is disposed on the second layer of the multilayer PCB board because it does not need to be connected to too many capacitive devices, and it does not have a fixed impedance requirement. In addition, the second layer of the multilayer PCB board can ensure the same as the lower surface medium of the third microstrip line, and the phase velocity is consistent. Since the medium is pressed, there is no need to worry about the copper skin floating due to heat.

Preferably, the impedances of the first microstrip line L2 and the second microstrip line L1, L3 are respectively matched with the impedance of the load, the debugging is simple, and the power allowed by the filter can be made larger.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. within the spirit and scope of the invention are intended to be included within the scope of the appended claims.

Claims

A microstrip filter comprising at least two units, wherein

Each unit includes a second microstrip line, a third microstrip line, and a first capacitor, wherein the second microstrip line has a first end and a second end, and one end of the first capacitor is coupled to the second micro a second end of the line with the other end connected to the ground; one end of the third microstrip line is connected to the second end of the second microstrip line, and the other end is open or grounded;

The adjacent two units are connected symmetrically by a first microstrip line, and the symmetric connection is: the first ends of the second microstrip lines of the adjacent two units are connected by the first microstrip line, or adjacent The second ends of the second microstrip lines of the two units are connected by the first microstrip line.
The microstrip filter according to claim 1, wherein each of the cells further includes a second capacitor, the first end of the second capacitor being connected to the first end of the second microstrip line, The second end of the second capacitor is connected to ground.
The microstrip filter according to claim 1, wherein each of the cells further includes a third capacitor connected in parallel across the second microstrip line.
The microstrip filter according to claim 1, wherein each of the cells further includes a second capacitor and a third capacitor, and wherein the first end of the second capacitor is connected to the second microstrip line The first end, the second end of the second capacitor is connected to the reference ground, and the third capacitor is connected in parallel at both ends of the second microstrip line.
The microstrip filter according to claim 1, wherein a width of said third microstrip line is smaller than a width of said first microstrip line and said second microstrip line.
A power device comprising a PCB board and a load and a filter disposed on the PCB, wherein the filter is the microstrip filter according to any one of claims 1-5 .
The power device according to claim 6, wherein the PCB board is a multilayer PCB board, and wherein the first microstrip line and the second microstrip line are disposed on the multilayer PCB board The first layer, the third microstrip line is disposed on the second layer of the multilayer PCB board.
The power device according to claim 6, wherein said third microstrip line is arranged in an S-shape or a disk-shaped arrangement on said PCB.
The power device of claim 6 wherein impedances of said first microstrip line and said second microstrip line respectively match impedance of said load.