阅读说明：本技术 一种用于工业互联网的5g微波全等宽平行线耦合滤波器的设计方法 (Design method of 5G microwave full-equal-width parallel line coupling filter for industrial internet ) 是由 杨保华 顾卫杰 施皓 邹华杰 于 2019-11-07 设计创作，主要内容包括：本发明是一种用于工业互联网的5G微波全等宽平行线耦合滤波器的设计方法。本发明采用N个耦合线段联组成平行线耦合带通滤波器,根据所述滤波器中心工作频率及相对带宽,确定修正中心频率；根据滤波器类型和带内波纹,确定各级串联线圈的电感量和并联电容器的电容量,采用奇偶模阻抗法,确定阻抗转换器参数的值,确定所述滤波器的奇偶模阻抗；根据电路板的化学腐蚀精度,确定各级耦合线段的长度和精度,使得所有平行线长度和宽度相等；将所得到的平行线耦合带通滤波器各级长度及宽度通过ADS仿真并输出为layout版图文件,根据layout版图文件,将平行线耦合带通滤波器的开路端圆角化处理。(The invention relates to a design method of a 5G microwave full-equal-width parallel line coupling filter for industrial internet. The invention adopts N coupling line sections to form a parallel line coupling band-pass filter, and determines a correction center frequency according to the center working frequency and the relative bandwidth of the filter; determining inductance of each stage of series coils and capacitance of a parallel capacitor according to the type and in-band ripple of the filter, determining the value of an impedance converter parameter by adopting an odd-even mode impedance method, and determining odd-even mode impedance of the filter; determining the length and the precision of each stage of coupling line segment according to the chemical corrosion precision of the circuit board, so that the length and the width of all parallel lines are equal; and (3) simulating and outputting the lengths and the widths of all levels of the obtained parallel line coupling band-pass filter into a layout file through ADS, and performing round-angle processing on the open end of the parallel line coupling band-pass filter according to the layout file.)

1. A design method of a 5G microwave full-equal-width parallel line coupling filter for industrial Internet is characterized by comprising the following steps: the method comprises the following steps:

step 1: adopting N coupled line sections to form a parallel line coupled band-pass filter, numbering from left to right, and determining the central working frequency and the relative bandwidth of the filter according to the wireless transmission system index of the filter;

step 2: determining a correction center frequency according to the center working frequency and the relative bandwidth of the filter;

and step 3: determining the inductance of each stage of series coil and the capacitance g of parallel capacitor according to the filter type and the in-band ripple₁,g₂…g_N；

And 4, step 4: determining impedance converter parameters Z by odd-even mode impedance method₀J₁,Z₀J₂…Z₀J_NA value of (d);

and 5: determining the odd-even mode impedance Z of the filter by odd-even mode impedance method_0e,Z_0o；

Step 6: determining the length and the precision of each stage of coupling line segment according to the chemical corrosion precision of the circuit board, so that the length and the width of all parallel lines are equal;

and 7: and (3) simulating and outputting the lengths and the widths of all levels of the obtained parallel line coupling band-pass filter into a layout file through ADS, and performing round-angle processing on the open end of the parallel line coupling band-pass filter according to the layout file.

2. The design method of the 5G microwave full-equal-width parallel line coupling filter for the industrial internet as claimed in claim 1, wherein the method comprises the following steps: the step 2 specifically comprises the following steps:

step 2.1: determining a correction center frequency according to the center working frequency and the relative bandwidth of the filter, and determining the correction center frequency according to the following formula:

where Δ f is the corrected center frequency, N is the order, N is 1,2,3 … N +1, f₀Is the filter centerThe operating frequency.

3. The design method of the 5G microwave full-equal-width parallel line coupling filter for the industrial internet as claimed in claim 1, wherein the method comprises the following steps: the step 4 is specifically

Determining values of the impedance converter parameters using an odd-even mode impedance method, the values of the impedance converter parameters being determined by:

wherein Z is₀Is 50 ohm impedance, Δ is relative bandwidth, J is the admittance inverter constant, Z₀J₁For the value of the first stage impedance transformer parameter, Z₀J₂For the value of the second stage impedance transformer parameter, Z₀J_NIs the value of the nth stage impedance converter parameter.

4. The design method of the 5G microwave full-equal-width parallel line coupling filter for the industrial internet as claimed in claim 1 is characterized by comprising the following steps: the step 5 specifically comprises the following steps:

determining the odd-even mode impedance Z of the filter by odd-even mode impedance method_0e,Z_0oThe odd-even mode impedance Z of the filter is determined by_0e,Z_0o：

Z_0e＝Z₀[1+JZ₀+(JZ₀)²]

Z_0o＝Z₀[1-JZ₀+(JZ₀)²]

Wherein Z is_0eAnd Z_0oAre odd-even mode resistances of said filterAnd (3) resisting.

5. The design method of the 5G microwave full-equal-width parallel line coupling filter for the industrial internet as claimed in claim 1 is characterized by comprising the following steps: the step 6 specifically comprises the following steps:

step 6.1: determining the length, the phase and the frequency offset of each stage of coupling line segment according to the chemical corrosion precision of the circuit board, so that the length and the width of all parallel lines are equal, and determining the length of each stage of coupling line segment according to the following formula:

wherein L is_aThe length of each coupling line segment is L, the length of the microstrip line after the fillet with the same area is L, and W is the width of the microstrip line;

step 6.2: determining the phase of each stage of coupling line segment according to the length of each stage of coupling line segment, and expressing the phase of each stage of coupling line segment by the following formula:

wherein f is₀For theoretical calculation of the central operating frequency, f, of the filter₀' actually measuring the central working frequency of the filter after actual corrosion;

step 6.3: determining the frequency offset according to the phases of the coupling line segments of each stage, and expressing the frequency offset by the following formula:

wherein, Δ f₀For frequency offset, λ_gIs the waveguide wavelength.

Technical Field

The invention relates to the technical field of full-equal-width parallel line coupling filters, in particular to a design method of a 5G microwave full-equal-width parallel line coupling filter for an industrial internet.

Background

In designing a circuit for transmitting a wireless signal, a filter is one of the most common approaches to avoid generation of harmonics and image signals.

The filter plays an important role in the design of a front-end circuit as a microwave device which is widely applied. With the development of microwave circuit integration, microstrip parallel line coupling filters have been widely used due to their advantages of easy integration, easy design, easy fabrication (printed circuit), large bandwidth, planar structure, large length-to-width ratio, and easy rotation for adapting to the receiver channel.

The invention relates to the technical field of radio frequency/microwave/millimeter wave/industrial internet and 5G, in particular to an all-equal-width parallel line coupling filter, which can accurately design the frequency response of the filter, improve the accuracy and consistency of the filter design and improve the performance of a wireless sensing circuit.

Filters of planar microstrip structure are the most commonly used bandpass filters. In the process of designing a filter, in addition to the requirements of bandwidth, out-of-band rejection, insertion loss and the like, the easy design, thermal reliability, consistency and the like of the filter are generally considered. The phenomenon that the line width of parallel lines of each order is discontinuous and the right angle is rounded in the corrosion processing process can cause processing errors and frequency deviation, the inconsistency of the design and the processing result can be obviously found, the high-frequency filter is difficult to realize the height consistency of the design and the detection, and the filter is difficult to design and has high research and development cost.

Disclosure of Invention

The invention provides a design method of a 5G microwave full-equal-width parallel line coupling filter for an industrial internet, aiming at improving the accuracy and consistency of the filter and solving the problem of discontinuity of each parallel, and the invention provides the following technical scheme:

a design method of a 5G microwave full-equal-width parallel line coupling filter for industrial Internet comprises the following steps:

step 1: adopting N coupled line sections to form a parallel line coupled band-pass filter, numbering from left to right, and determining the central working frequency and the relative bandwidth of the filter according to the wireless transmission system index of the filter;

step 2: determining a correction center frequency according to the center working frequency and the relative bandwidth of the filter;

and step 3: determining the inductance of each stage of series coil and the capacitance g of parallel capacitor according to the filter type and the in-band ripple₁,g₂…g_N；

And 4, step 4: determining impedance converter parameters Z by odd-even mode impedance method₀J₁,Z₀J₂…Z₀J_NA value of (d);

and 5: determining the odd-even mode impedance Z of the filter by odd-even mode impedance method_0e,Z_0o；

Step 6: determining the length and the precision of each stage of coupling line segment according to the chemical corrosion precision of the circuit board, so that the length and the width of all parallel lines are equal;

and 7: and (3) simulating and outputting the lengths and the widths of all levels of the obtained parallel line coupling band-pass filter into a layout file through ADS, and performing round-angle processing on the open end of the parallel line coupling band-pass filter according to the layout file.

Preferably, the step 2 specifically comprises:

step 2.1: determining a correction center frequency according to the center working frequency and the relative bandwidth of the filter, and determining the correction center frequency according to the following formula:

where Δ f is the corrected center frequency, N is the order, N is 1,2,3 … N +1, f₀Is the filter center operating frequency.

Preferably, the step 4 is specifically

Determining values of the impedance converter parameters using an odd-even mode impedance method, the values of the impedance converter parameters being determined by:

wherein Z is₀Is 50 ohm impedance, Δ is relative bandwidth, J is the admittance inverter constant, Z₀J₁For the value of the first stage impedance transformer parameter, Z₀J₂For the value of the second stage impedance transformer parameter, Z₀J_NIs the value of the nth stage impedance converter parameter.

Preferably, the step 5 specifically comprises:

determining the odd-even mode impedance Z of the filter by odd-even mode impedance method_0e,Z_0oThe odd-even mode impedance Z of the filter is determined by_0e,Z_0o：

Z_0e＝Z₀[1+JZ₀+(JZ₀)²]

Z_0o＝Z₀[1-JZ₀+(JZ₀)²]

Wherein Z is_0eAnd Z_0oAre the odd-even mode impedances of the filter.

Preferably, the step 6 specifically includes:

step 6.1: determining the length, the phase and the frequency offset of each stage of coupling line segment according to the chemical corrosion precision of the circuit board, so that the length and the width of all parallel lines are equal, and determining the length of each stage of coupling line segment according to the following formula:

wherein，L_aThe length of each coupling line segment is L, the length of the microstrip line after the fillet with the same area is L, and W is the width of the microstrip line;

step 6.2: determining the phase of each stage of coupling line segment according to the length of each stage of coupling line segment, and expressing the phase of each stage of coupling line segment by the following formula:

wherein f is₀For theoretical calculation of the central operating frequency, f, of the filter₀' actually measuring the central working frequency of the filter after actual corrosion;

step 6.3: determining the frequency offset according to the phases of the coupling line segments of each stage, and expressing the frequency offset by the following formula:

wherein, Δ f₀For frequency offset, λ_gIs the waveguide wavelength.

The invention has the following beneficial effects:

according to the parallel line coupling filter designed by the invention, a round angle design scheme is adopted for the open end of the parallel line coupling filter to replace the traditional length compensation scheme, and in order to avoid discontinuity caused by different widths of the parallel lines of adjacent steps, particularly small width difference, parallel lines with very similar lengths and widths of the steps need to be set to be the same in length and width.

The design of the filter with the full equal width of each order solves the problem of processing error and frequency offset caused by discontinuous non-line width of parallel lines of each order. The problem of current parallel line coupling filter each order parallel line all have the line width discontinuous phenomenon, cause machining error easily to lead to frequency offset, cause the inconsistent phenomenon of design and processing is solved. The design of the full equal width is easy to realize the precise design of the filter, and the whole design flow becomes simple and smooth. The design of the rounded corners avoids frequency shifts caused by process erosion.

(1) At the open end of each order of parallel lines, the frequency is deviated due to the rounding phenomenon caused by the corrosion processing technology, the higher the frequency is, the narrower the line width is, the more serious the rounding corrosion phenomenon is, and the more difficult the precise design and processing of the high-frequency filter are caused.

(2) The invention of the parallel line coupling filter with full equal width of round angle provides good performance guarantee for the radio frequency/microwave/millimeter wave multi-channel radiometer system.

(3) The derivation of the correlation formula gives an accurate design of the filter, ensuring that consistent performance is provided for a multi-channel receiver radiometer system.

(4) The invention of the filleted full-equal-width filter provides a whole set of related design process, and reduces the difficulty of accurately designing the high-frequency filter.

Drawings

Figure 1 is an N coupled line bandpass filter structure;

FIG. 2 is an equivalent circuit of a coupled line segment;

FIG. 3 is an overall equivalent circuit diagram of the filter;

FIG. 4 is a layout of a full-equal-width parallel line coupling filter with rounded open ends;

FIG. 5 is a view of a single parallel line, FIG. 5- (a) is a single round-corner parallel line, and FIG. 5- (b) is an equal-area right-angle parallel line;

FIG. 6 shows the corner frequency shift corresponding to different center frequencies when n is 4 th order, where FIG. 6- (a) shows a frequency of 5GHz, FIG. 6- (b) shows a frequency of 12GHz, and FIG. 6- (c) shows a frequency of 20.2 GHz; FIG. 6- (d) is at 26GHz and FIG. 6- (e) is at 34 GHz;

FIG. 7 shows the corner frequency shift corresponding to different center frequencies when n is 5 th order, where FIG. 7- (a) shows 8GHz, FIG. 7- (b) shows 12GHz, and FIG. 7- (c) shows 20 GHz; FIG. 7- (d) is at 26GHz and FIG. 7- (e) is at 34 GHz;

FIG. 8 shows the corner frequency shift corresponding to different center frequencies when n is 6 th order, where FIG. 8- (a) shows 8GHz, FIG. 8- (b) shows 12GHz, and FIG. 8- (c) shows 20 GHz; FIG. 8- (d) is at 26GHz and FIG. 8- (e) is at 34 GHz;

FIG. 9 is a graph of center frequency, bandwidth and frequency shift, FIG. 9- (a) is a graph of center frequency and frequency shift, and FIG. 9- (b) is a graph of bandwidth and frequency shift;

FIG. 10 is a sample plot of a full-width equal-length rounded parallel-line coupled filter, FIG. 10- (a) single sample plot, and FIG. 10- (b) multiple test samples;

FIG. 11 is a sample test chart of an equal-length filter with three different center frequencies, in which FIG. 11- (a) shows a sample test with a center frequency of 12GHz, FIG. 11- (b) shows a sample test with a center frequency of 26.2GHz, and FIG. 11- (c) shows a sample test with a center frequency of 34 GHz.

Detailed Description

The present invention will be described in detail with reference to specific examples.