阅读说明：本技术 基于电感加载耦合线的宽带小型化同向定向耦合器及设计方法 (Broadband miniaturization same-direction directional coupler based on inductance loading coupling line and design method ) 是由 刘宏梅 官明瑶 张红晓 王雪娇 王佳慧 房少军 王钟葆 于 2021-06-04 设计创作，主要内容包括：本发明公开了一种基于电感加载耦合线的宽带小型化同向定向耦合器及设计方法,具体方案为：包括电感加载平行耦合线、并联电容、并联开路线和四个50欧姆输入/输出端口；所述电感加载平行耦合线包括第一段耦合线、第二段耦合线和跨接电感；所述第一段耦合线包括第一耦合线和第二耦合线；所述第二段耦合线包括第三耦合线和第四耦合线；并联电容包括第一电容和第二电容；所述并联开路线包括第一段并联开路线、第二段并联开路线、第三段并联开路线和第四段并联开路线；本装置可以实现小体积、宽频带,同时输出端口在同侧的特点。由于采用了上述技术方案,本发明提供的一种基于电感加载耦合线的宽带小型化同向定向耦合器,具有体积小、频带宽、结构简单和易加工的特点,适于广泛推广。(The invention discloses a broadband miniaturization same-direction directional coupler based on an inductance loading coupling line and a design method thereof, and the specific scheme is as follows: the parallel coupling line comprises an inductance loading parallel coupling line, a parallel capacitor, a parallel open line and four 50-ohm input/output ports; the inductance loading parallel coupling line comprises a first section of coupling line, a second section of coupling line and a cross-over inductance; the first section of coupled line comprises a first coupled line and a second coupled line; the second section of coupled lines comprise a third coupled line and a fourth coupled line; the parallel capacitor comprises a first capacitor and a second capacitor; the parallel open line comprises a first section of parallel open line, a second section of parallel open line, a third section of parallel open line and a fourth section of parallel open line; the device can realize the characteristics of small volume, wide frequency band and output ports on the same side. Due to the adoption of the technical scheme, the broadband miniaturization same-direction directional coupler based on the inductance loading coupling line has the characteristics of small volume, wide frequency band, simple structure and easiness in processing, and is suitable for wide popularization.)

1. The utility model provides a miniaturized syntropy directional coupler of broadband based on inductance loading coupled line which characterized in that: the parallel coupling circuit comprises an inductance loading parallel coupling line (1), a parallel capacitor, a parallel open line and four 50-ohm input/output ports;

the inductance loading parallel coupling line (1) comprises a first section of parallel coupling line (11), a second section of parallel coupling line (12) and a cross-over inductance (13); the first section of parallel coupled lines (11) comprises a first coupled line (111) and a second coupled line (112); the second section of parallel coupled lines (12) comprises a third coupled line (121) and a fourth coupled line (122); the parallel capacitance comprises a first parallel capacitance (21) and a second parallel capacitance (22); the parallel open line comprises a first section of parallel open line (31), a second section of parallel open line (32), a third section of parallel open line (33) and a fourth section of parallel open line (34);

the first coupling line (111) is connected with a third coupling line (121), and the second coupling line (112) is connected with a fourth coupling line (122); the jumper inductor (13) is bridged at the right end of the first section of parallel coupling line (11); the first parallel capacitor (21) is connected with the right end of the first coupling line (111), and the second parallel capacitor (22) is connected with the right end of the second coupling line (112); the first section of parallel open line (31) is connected with the left end of the first coupling line (111), the second section of parallel open line (32) is connected with the left end of the second coupling line (112), the third section of parallel open line (33) is connected with the right end of the third coupling line (121), and the fourth section of parallel open line (34) is connected with the right end of the fourth coupling line (122);

the parameters of the first section of parallel coupling line (11) and the second section of parallel coupling line (12) are the same; the first parallel capacitor (21) and the second parallel capacitor (22) have the same parameters; the parameters of the first section of parallel open line (31), the second section of parallel open line (32), the third section of parallel open line (33) and the fourth section of parallel open line (34) are the same.

2. The broadband miniaturized equidirectional directional coupler based on the inductively loaded coupled line as recited in claim 1, wherein: the characteristic impedance of the parallel open circuit line of the coupler is 50 ohms, which is the same as the input/output port impedance.

3. The broadband miniaturized equidirectional directional coupler based on the inductively loaded coupled line as recited in claim 1, wherein: the electrical length of the parallel coupled lines is not uniquely determined according to miniaturization requirements.

4. The broadband miniaturized equidirectional directional coupler based on the inductively loaded coupled line as recited in claim 1, wherein: the electrical length of the parallel open lines is not unique.

5. The broadband miniaturized equidirectional directional coupler based on the inductively loaded coupled line as recited in claim 1, wherein: the odd mode impedance of the parallel coupled lines is determined by the even mode impedance of the parallel coupled lines and the electrical length of the parallel open line.

6. The design method of the broadband miniaturized co-directional coupler based on the inductively loaded coupled line as claimed in claims 1-5, comprising the steps of:

step 1: decomposing the four-port network into four single-port networks for analysis by using an odd-even mode analysis method to obtain the input impedance of the single-port networks under odd-odd mode excitation, odd-even mode excitation, even-odd mode excitation and even-even mode excitation;

step 2: substituting the input impedance of the single-port network into an expression according to the conditions of ideal matching of the input port of the directional coupler and ideal isolation of the isolated port Andobtaining the input impedance Z of the single-port network under odd-odd mode excitation, odd-even mode excitation, even-odd mode excitation and even-even mode excitation_oo、Z_oe、Z_eeAnd Z_eoAnd input/output port impedance Z₀Expression (c):

and step 3: substituting the input impedance of the single port into an expression according to the coupling condition of the directional couplerAndin the method, the input impedance Z of four single-port networks is obtained_oo、Z_oe、Z_eeAnd Z_eoExpression for coupling degree k:

and 4, step 4: according to the expression in the step 3, inputting impedance Z of the single-port network under odd-odd mode excitation and even-odd mode excitation_oo、Z_oeBrought into it to the firstThe even mode impedance Z of a section of parallel coupled line (11)_1eThe degree of coupling k is a known variable, the electrical length theta of the first section of parallel coupled lines (11) being independent of the degree of coupling k₁The odd-mode impedance Z of the first section of the parallel coupling line (11) can be determined according to the actual miniaturization requirement_1oExpression (c):

drawing the electrical length θ of the parallel open circuit₂At different times, the odd-mode impedance Z of the first section of parallel coupled line (11)_1oImpedance Z of random even mode_1eCan select the electrical length theta of the proper parallel open line₂Further calculating to obtain the even mode impedance Z of the first section of parallel coupling line (11)_1eAnd odd mode impedance Z_1oA value of (d);

and 5: inputting impedance Z of the single-port network obtained in the step 1_oo、Z_eo、Z_eeAnd Z_eoThe capacitance value C of the parallel capacitors (21, 22) is obtained by calculation according to the expression 1 after being substituted into the two expressions obtained in the step 3₁Then calculating to obtain the inductance value L of the cross-over inductor₁The expression of (1);

wherein, ω is 2 π f, Z₀Characteristic impedances for the four input/output ports and the parallel open lines; z_1eThe impedance is the even mode characteristic impedance of the first section of parallel coupling line (11) and the second section of parallel coupling line (12); z_1oThe odd-mode characteristic impedance of the first section of parallel coupling line (11) and the second section of parallel coupling line (12); theta₁The electrical length of the first section of parallel coupling line (11) and the second section of parallel coupling line (12); theta₂Electrical length for parallel open lines; c₁Is the capacitance value of the parallel capacitor; l is₁Is the inductance across the inductance (13).

Technical Field

The invention belongs to the technical field of electronics, relates to a microwave device, and particularly relates to a broadband miniaturized same-direction directional coupler based on an inductive loading coupling line and a design method.

Background

Nowadays, people's increasing demand for informatization has greatly promoted the development of wireless communication technology towards large capacity, high transmission rate, high security and the like. The continuous and rapid development of wireless communication technology also brings new challenges and higher requirements to the microwave radio frequency circuit technology in communication equipment. Therefore, in order to adapt to the development of the current wireless communication technology, the research on the high-performance microwave device with broadband, integration and miniaturization has great engineering application value.

Directional couplers are key passive devices for communication systems, beam forming, balanced mixers or amplifiers. There are generally three directional couplers including a homodyne coupler, a counter coupler and a cross coupler. The method specifically comprises the following steps: if the input end and the straight-through end are on the same transmission line, the coupling end and the isolation end are on the other transmission line, and the input end and the isolation end are on the same side, a homodromous coupler is formed; if the input end and the straight-through end are on the same transmission line, the coupling end and the isolation end are on the other transmission line, and the input end and the coupling end are on the same side, a reverse coupler is formed; if the input end and the isolation end are on the same transmission line, the coupling end and the through end are on the other transmission line, and the input end and the isolation end are on the same side, a cross directional coupler is formed. The homodromous coupler is usually composed of branch lines, so that the homodromous coupler has the inherent characteristics of large size and narrow bandwidth. The coupling line directional coupler based on inductive loading has the characteristics of small volume, wide frequency band, low cost and easiness in processing, and meanwhile, as the coupling end and the straight-through end of the coupler are arranged on the same side, when the coupler is applied to a microwave circuit, the circuit layout can be simplified.

Disclosure of Invention

According to the problems in the prior art, the invention discloses a broadband miniaturization same-direction directional coupler based on an inductance loading coupling line, which has the specific scheme that: the parallel coupling line comprises an inductance loading parallel coupling line, a parallel capacitor, a parallel open line and four 50-ohm input/output ports;

the inductance loading parallel coupling line comprises a first section of parallel coupling line, a second section of parallel coupling line and a cross-over inductance; the first section of parallel coupled lines comprises a first coupled line and a second coupled line; the second section of parallel coupling lines comprise a third coupling line and a fourth coupling line; the parallel capacitors comprise a first parallel capacitor and a second parallel capacitor; the parallel open line comprises a first section of parallel open line, a second section of parallel open line, a third section of parallel open line and a fourth section of parallel open line;

the first coupling line is connected with the third coupling line, and the second coupling line is connected with the fourth coupling line; the jumper inductor is bridged at the right end of the first section of parallel coupling line; the first parallel capacitor is connected with the right end of the first coupling line, and the second parallel capacitor is connected with the right end of the second coupling line; the first section of parallel open line is connected with the left end of the first coupling line, the second section of parallel open line is connected with the left end of the second coupling line, the third section of parallel open line is connected with the right end of the third coupling line, and the fourth section of parallel open line is connected with the right end of the fourth coupling line;

the parameters of the first section of parallel coupling line are the same as those of the second section of parallel coupling line; the first parallel capacitor and the second parallel capacitor have the same parameters; the parameters of the first section of parallel open circuit line, the second section of parallel open circuit line, the third section of parallel open circuit line and the fourth section of parallel open circuit line are the same.

The characteristic impedance of the parallel open circuit line of the coupler is 50 ohms, which is the same as the input/output port impedance.

The electrical length of the parallel coupled lines is not unique and can be determined according to miniaturization requirements.

The electrical length of the parallel open lines is not unique.

The odd mode impedance of the parallel coupled lines is determined by the even mode impedance of the parallel coupled lines and the electrical length of the parallel open line.

Due to the adoption of the technical scheme, the broadband miniaturization same-direction directional coupler based on the inductance loading coupling line provided by the invention can realize a directional coupler with a wide frequency band and small volume and the same-direction output due to the adoption of the specific structure, and in addition, the coupler has a simple structure, is easy to process and is very suitable for practical large-scale application occasions.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic structural diagram of a broadband miniaturized co-directional coupler based on an inductively-loaded coupled line according to the present invention;

FIG. 2 is an equivalent circuit diagram of a single-port network of the broadband miniaturized homodromous directional coupler based on the inductively loaded coupled line according to the present invention;

FIG. 3 is an S-parameter curve of the broadband miniaturized equidirectional directional coupler based on the inductively loaded coupled line according to the present invention;

fig. 4 is a phase curve between output ports of the broadband miniaturized co-directional coupler based on the inductively loaded coupled line according to the present invention.

In the figure: 1. the inductor comprises an inductor loading parallel coupling line 11, a first section of parallel coupling line 12, a second section of parallel coupling line 13, a cross-over inductor 111, a first coupling line 112, a second coupling line 121, a third coupling line 122, a fourth coupling line 21, a first parallel capacitor 22, a second parallel capacitor 31, a first section of parallel open circuit line 32, a second section of parallel open circuit line 33, a third section of parallel open circuit line 34 and a fourth section of parallel open circuit line.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

Fig. 1 is a schematic structural diagram of a broadband miniaturized directional coupler based on an inductively-loaded coupled line according to the present invention, where the directional coupler of the present embodiment may include: the circuit comprises an inductance loading parallel coupling line 1, a parallel capacitor, a parallel open line and four 50-ohm input/output ports.

Further, the first coupling line 111 is connected to the third coupling line 121, and the second coupling line 112 is connected to the fourth coupling line 122; the jumper inductor 13 is bridged at the right end of the first section of parallel coupling line 11; the first parallel capacitor 21 is connected with the right end of the first coupling line 111, and the second parallel capacitor 22 is connected with the right end of the second coupling line 112; the first section of parallel open line 31 is connected with the left end of the first coupling line 111, the second section of parallel open line 32 is connected with the left end of the second coupling line 112, the third section of parallel open line 33 is connected with the right end of the third coupling line 121, and the fourth section of parallel open line 34 is connected with the right end of the fourth coupling line 122; the parameters of the first section of parallel coupling line 11 are the same as those of the second section of parallel coupling line 12; the first parallel capacitor 21 and the second parallel capacitor 22 have the same parameters; the parameters of the first section of parallel open line 31, the second section of parallel open line 32, the third section of parallel open line 33 and the fourth section of parallel open line 34 are the same.

Further, the electrical length of the parallel coupled lines is not unique and can be determined according to miniaturization requirements.

Specifically, in this embodiment, an equal power ratio between the two output ports can be realized. And converting the four-port network of the coupler into four single-port networks for analysis by using an odd-even mode analysis method, and calculating circuit parameters.

Under the excitation of the even mode, the current on the symmetrical plane of the directional coupler is zero, and the directional coupler is equivalently an open circuit. Under the excitation of an odd mode, the voltage on the symmetrical plane of the directional coupler is zero, and the voltage is equivalent to a short circuit. Fig. 2(a) shows an even-even mode equivalent circuit of the directional coupler. Z_1eIs the even mode characteristic impedance of the first section of parallel coupled line 11 and the second section of parallel coupled line 12, theta₁The electrical length, C, of the first segment of parallel coupled line 11 and the second segment of parallel coupled line 12₁Is the capacitance value of the parallel capacitor, Z₀Impedance of parallel open circuit line and input/output port, theta₂The electrical length of the parallel open line.

Fig. 2(b) shows an even-odd mode equivalent circuit of the directional coupler. Z_1eIs the even mode characteristic impedance of the first section of parallel coupled line 11 and the second section of parallel coupled line 12, theta₁Is the electrical length, Z, of the first segment of parallel coupled line 11 and the second segment of parallel coupled line 12₀Impedance of parallel open circuit line and input/output port, theta₂The electrical length of the parallel open line.

Fig. 2(c) shows an equivalent circuit of the odd-even mode of the directional coupler. Z_1oIs the odd-mode characteristic impedance of the first segment of parallel coupled line 11 and the second segment of parallel coupled line 12₁The electrical length, C, of the first segment of parallel coupled line 11 and the second segment of parallel coupled line 12₁Is the capacitance value of the parallel capacitor, Z₀Impedance of parallel open circuit line and input/output port, theta₂For the electrical length of the parallel open circuit line, L₁Is the inductance across the inductance 13.

Fig. 2(d) shows an odd-odd mode equivalent circuit of the directional coupler. Z_1oIs the odd-mode characteristic impedance of the first segment of parallel coupled line 11 and the second segment of parallel coupled line 12₁Is the electrical length, Z, of the first segment of parallel coupled line 11 and the second segment of parallel coupled line 12₀Is connected in parallel toImpedance of the lines and input/output ports, θ₂The electrical length of the parallel open line.

The input impedance of the four single-port networks in fig. 2 can be obtained, and then the parameters are solved by using the characteristics of the directional coupler according to the relationship between the characteristic impedance and the scattering parameters, so that the design formula of the directional coupler in the invention can be obtained, and the solving steps are as follows:

step 1: by utilizing an odd-even mode analysis method, the four-port network is decomposed into four single-port networks for analysis, and the input impedance of the single-port network under odd-odd mode excitation, odd-even mode excitation, even-odd mode excitation and even-even mode excitation can be obtained.

Step 2: substituting the input impedance of the single-port network into an expression according to the conditions of ideal matching of the input port of the directional coupler and ideal isolation of the isolated port Andobtaining the input impedance Z of the single-port network under odd-odd mode excitation, odd-even mode excitation, even-odd mode excitation and even-even mode excitation_oo、Z_oe、Z_eeAnd Z_eoAnd input/output port impedance Z₀Expression (c):

and step 3: substituting the input impedance of the single port into an expression according to the coupling condition of the directional couplerAndin the method, the input impedance Z of four single-port networks is obtained_oo、Z_oe、Z_eeAnd Z_eoExpression for coupling degree k:

and 4, step 4: according to the expression in the step 3, inputting impedance Z of the single-port network under odd-odd mode excitation and even-odd mode excitation_oo、Z_oeInto which the even mode impedance Z of the first section of parallel coupled line 11 is brought_1eThe degree of coupling k is a known variable, the electrical length theta of the first segment of parallel coupled lines 11 being independent of₁The odd-mode impedance Z of the first section of the parallel coupling line 11 can be determined according to the actual miniaturization requirement_1oExpression (c):

drawing the electrical length θ of the parallel open circuit₂At different times, the odd mode impedance Z of the first segment of parallel coupled line 11_1oImpedance Z of random even mode_1eCan select the electrical length theta of the proper parallel open line₂Further calculating to obtain the even mode impedance Z of the first section of parallel coupling line 11_1eAnd odd mode impedance Z_1oThe value of (c).

And 5: inputting impedance Z of the single-port network obtained in the step 1_oo、Z_eo、Z_eeAnd Z_eoThe capacitance value C of the parallel capacitor is obtained by calculation according to the expression 1₁Then calculating to obtain the inductance value L of the cross-over inductor₁Is described in (1).

Where ω is 2 pi f.

In the embodiment of the invention, the center frequency of the coupler is 2GHz, the coupling degree is 3dB (the coupling coefficient k is 0.707), and the input/output port impedance and the parallel open-circuit line impedance Z₀50 Ω. Selecting theta₁＝35°、θ₂＝15°、Z_1eZ is calculated as 100 Ω_1o＝24.8Ω，C₁＝1.4pF、L₁2.4 nH. The broadband miniaturization same-direction directional coupler based on the inductive loading coupling line is designed according to the selected characteristic impedance and the electrical length. As shown in FIGS. 3 and 4, the directional coupler of the same directional coupler of the present embodiment has return loss (| S)₁₁|<-15dB) greater than 15dB, 41.5% (1.63 GHz-2.46 GHz), isolation (| S)₄₁|<-15dB) is greater than 15dB, is 40% (1.63 GHz-2.43 GHz), and is 33.5% (1.76 GHz-2.43 GHz) with a degree of coupling of 3 ± 0.5 dB. The relative bandwidth of 90 DEG +/-5 DEG phase difference between the output ports is 42% (1.65 GHz-2.49 GHz)

The technical indexes adopted by the embodiment are as follows:

input/output port impedance: z₀＝50Ω；

Parallel open circuit: z₀＝50Ω；

Coupling coefficient: k is 0.707;

coupling degree: 3 +/-0.5 dB;

return loss: >15 dB;

isolation degree: >15 dB;

phase difference between output ports: 90 DEG +/-5 deg.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.