CN202308258U - Power divider integrated with single-frequency band-pass filters - Google Patents

Abstract

The utility model discloses a power divider integrated with a single-frequency band-pass filter. Including the upper microstrip structure, the isolation element, the middle dielectric substrate and the lower ground metal plate. Each power divider integrated with a single-frequency bandpass filter includes two open-ended single-frequency bandpass loop filters and an isolation element connected between the two open-ended single-frequency bandpass loop filters. The input impedance of the power divider integrated with a single-frequency band-pass filter is the same as the output impedance, and the input and output impedance of each open-circuit single-frequency band-pass loop filter is the input impedance or output impedance of the power divider integrated with a single-frequency band-pass filter Resistive

times. Each open-terminated single-frequency bandpass loop filter is composed of two U-shaped half-wavelength resonators with the same structure. Isolation elements can be resistors, capacitors or inductors. The utility model can be used in various radio frequency front-end systems, has the functions of power distribution and frequency selection, and is beneficial to the integration and miniaturization of devices.

Description

Power divider with integrated single-band bandpass filter

technical field

The utility model relates to a power divider with a filter function, in particular to a power divider integrated with a single-frequency bandpass filter, which can be applied to a radio frequency front-end circuit with a filter function. the

Background technique

Power splitters are a fundamental part of microwave circuits and are used in almost all antenna arrays and balanced circuits because of their ability to separate and combine signals. Bandpass filters are another indispensable device in wireless communication systems because they can separate out the desired frequency bands. Both devices, power dividers and bandpass filters, co-exist in many microwave systems. the

In the past few decades, there has been a lot of research on power dividers. The focus of the research is widening the frequency band, reducing the area, dual frequency response and harmonic suppression. the

On the other hand, bandpass filter is also an important research field in passive circuit design. Single passband and multipassband filters are two different research directions. On the one hand, ultra-wideband, harmonic suppression and tunable filters are important considerations in the design of single-pass band-pass filters. On the other hand, ladder impedance filters are widely used in the design of multi-pass band-pass filters. Recently, some studies have shown that the multi-frequency response can be obtained by loading the open-circuit branch to the center of the resonator. the

In many systems, power splitters and filters usually need to be connected together to achieve the functions of separating and filtering signals. However, all the researches on the power divider and filter mentioned above only focus on their own characteristics, and rarely consider the possibility of combining the two. In traditional systems, discrete devices are usually used to realize these two functions. However, using discrete components makes the size of the module large. Therefore, in order to reduce the size, dual-function devices are in demand. Dual-function devices with the functions of separating power signal and frequency selection at the same time have been studied by some scholars. In K. J. Song, and Q. Xue, "Novel Ultra-Wideband (UWB) Multilayer Slotline Power Divider With Bandpass Response," IEEE Microw. Wireless Compon. Lett., vol. 20, no. 1, pp. 13- 15, Jan, 2010. In, the author completed an ultra-wideband power divider with bandpass response. Multi-layer microstrip slotted line coupling is used to separate signals and block unwanted frequency bands. In addition, a Wilkinson Power Divider with Bandpass Response and Harmonic Suppression is designed in P. Cheong, K. Lai, and K. Tam, "Compact Wilkinson Power Divider with Simultaneous Bandpass Response and Harmonic Suppression," proposed in 2010 IEEE MTT-S International Microwave Symposium Digest, Snaheim, USA, 2010. In this design, interdigitated ladder impedance coupled lines are used to achieve the required function. In addition, mentioned in X. Y. Tang, and K. Mouthaan, "Filter Integrated Wilkinson Power Dividers," Microwave and Optical Technology Letters, vol. 52, no. 12, pp. 2830-2833, Dec, 2010. , the Π-type transmission line can be integrated into the power divider, however, the article only proposes that the Π-type transmission line can be used instead of a real filter for realizing the characteristics. So far, there has not been a device that integrates a real filter into a power divider. In order to fill this gap, the utility model proposes a new type of power divider integrated with a single-frequency band-pass filter. the

Utility model content

The purpose of the utility model is to overcome the above-mentioned shortcomings in the prior art, and provide a power divider integrated with a single-frequency band-pass filter. In the utility model, the filter is used as an impedance converter to replace the traditional quarter-wavelength transmission line. Resistors, capacitors or inductors are connected to the open ends of the two filters as isolation components to obtain good isolation effect. The proposed structure has a smaller size and enhanced circuit integration because of the special placement of the isolation devices. Because the single-frequency band-pass filter is integrated in the power divider, the utility model can realize the functions of power distribution and frequency selection at the same time. the

For realizing the utility model purpose, the technical scheme adopted in the utility model is as follows:

A power divider that integrates a single-frequency bandpass filter, including an upper microstrip structure, an isolation element, an intermediate dielectric substrate and a lower ground metal plate, the upper microstrip structure and isolation elements are attached to the upper surface of the intermediate dielectric plate, and the intermediate dielectric The lower surface of the board is grounded metal; it is characterized in that the upper microstrip structure includes two open-ended single-frequency band-pass loop filters, and the two open-ended single-frequency band-pass loop filters have the same structure and are arranged in a symmetrical structure up and down. One input port of the open-ended single-frequency band-pass loop filter is used as the input port of the power divider integrated with the single-frequency band-pass filter, and the output ports of the two open-ended single-frequency band-pass loop filters are used as the input port of the integrated single-frequency band-pass filter. Two output ports of the power divider.

In the above-mentioned power divider integrated with a single-frequency bandpass filter, the upper open-circuit single-frequency bandpass ring filter is composed of two U-shaped half-wavelength resonators coupled; the structures of the two U-shaped half-wavelength resonators are exactly the same, The U-shaped half-wavelength resonator connected to the input port is composed of the second microstrip line, the first microstrip line and the third microstrip line, and the intersection of the first microstrip line and the third microstrip line is connected to Input port; the U-shaped half-wavelength resonator connected to the first output port is composed of the fifth microstrip line, the fourth microstrip line and the sixth microstrip line, and the fourth microstrip line and the fifth microstrip line The intersection is connected to the first output port; one end of the isolation element is connected to the open end of the sixth microstrip line of the upper open-circuit single-frequency band-pass loop filter, and the other end is connected to the open-terminal single-frequency band-pass loop filter located below The open ends of the corresponding microstrip lines are connected. the

In the above-mentioned power divider integrated with a single-frequency bandpass filter, the length L of the U-shaped half-wavelength resonator is one-half of the wavelength λ corresponding to the resonant frequency f of the open-ended single-frequency bandpass ring filter; wherein, L is the actual length of the microstrip line; the actual length L of the microstrip line is the sum of the lengths of the first microstrip line, the second microstrip line, and the third microstrip line.

In the above-mentioned power divider integrated with a single-frequency band-pass filter, each open-ended single-frequency band-pass loop filter has two coupling paths, wherein the first coupling path is parallel to the second microstrip line and the fifth microstrip line The coupling part of the second coupling path is a coupling part parallel to the upper and lower sides of the third microstrip line and the sixth microstrip line. the

In the above-mentioned power divider integrated with a single-frequency bandpass filter, when the U-shaped half-wavelength resonator resonates, the signal at the input end and the signal at the output end of the open-circuit single-frequency bandpass ring filter have a phase shift of -90°. the

倍。  In the above-mentioned power divider integrated with a single-frequency band-pass filter, the input impedance of the power divider integrated with a single-frequency band-pass filter is the same as the output impedance, and the input and output impedances of each open-circuit single-frequency band-pass loop filter are integrated The input impedance or output impedance of the power divider of the single frequency bandpass filter

times.

In the above-mentioned power divider integrated with a single-frequency bandpass filter, the isolation element is a resistor, a capacitor or an inductor. the

Compared with the prior art, the utility model has the following advantages and technical effects:

(1) A single-band bandpass filter is integrated in the traditional power divider, which can realize the functions of power distribution and signal filtering at the same time, and has a larger size reduction than the module composed of discrete power dividers and filters. Small, which is conducive to the integration and miniaturization of the RF front-end system.

(2) The power divider integrated with a single-frequency bandpass filter has lower insertion loss than the traditional module consisting of a discrete power divider and filter. the

Description of drawings

Figure 1 is a block diagram of a power splitter integrating a single-frequency bandpass filter. the

Figure 2a is a schematic diagram of an open-ended bandpass filter. the

Fig. 2b is a graph of transmission characteristics of an open-ended bandpass filter. the

Fig. 3 is a schematic structural diagram of a power divider integrated with a single-frequency band-pass filter. the

Figure 4a is a graph of the transfer characteristic of a power splitter integrated with a single-frequency bandpass filter. the

Figure 4b is a graph of the output return loss and isolation factor of a power splitter integrated with a single-band bandpass filter. the

Detailed ways

The utility model will be described in further detail below in conjunction with the accompanying drawings, but the scope of protection claimed by the utility model is not limited to the scope of the following examples. the

As shown in Figure 1, the power divider integrated with a single-frequency bandpass filter includes an upper microstrip structure, isolation elements, a middle dielectric substrate and a lower ground metal plate, and the upper microstrip structure and isolation elements are attached to the middle dielectric plate Surface, the lower surface of the intermediate dielectric plate is grounded metal; the upper microstrip structure includes two open-terminal single-frequency band-pass loop filters, the two open-terminal single-frequency band-pass loop filters have the same structure, and are arranged in a symmetrical structure up and down. The two open-ended single-frequency band-pass loop filters share one input port as the input port of the power divider integrated with the single-frequency band-pass filter, and the output ports of the two open-ended single-frequency band-pass loop filters serve as the integrated single-frequency band-pass filter. The two output ports of the power divider; one end of the isolation element is connected to the open end of the sixth microstrip line of the upper open-circuit single-frequency band-pass loop filter, and the other end is connected to the lower open-circuit single-frequency band-pass loop filter The open end of the corresponding microstrip line of the device is connected to enhance the isolation. Wherein, the isolation element can be a resistor, a capacitor or an inductor. the

As shown in Figure 2a, each open-terminated single-frequency bandpass loop filter is composed of two U-shaped half-wavelength resonators coupled; each U-shaped half-wavelength resonator has the same structure and is composed of microstrip line connections; it is connected to the input port The U-shaped half-wavelength resonator is composed of the second microstrip line 2, the first microstrip line 1 and the third microstrip line 3, and the intersection of the first microstrip line 1 and the third microstrip line 3 is connected to The input port, the U-shaped half-wavelength resonator connected to the output port is composed of the fifth microstrip line 5, the fourth microstrip line 4 and the sixth microstrip line 6, and the fourth microstrip line 4 and the fifth microstrip line The intersection point of line 5 is connected to output port; The length L of U-shaped half-wavelength resonator is 1/2 of the wavelength λ corresponding to the resonant frequency f of described terminal open-circuit single-frequency band-pass loop filter; Wherein, L is the actual micro The length of the strip line; the actual length L of the microstrip line is the sum of the lengths of the first microstrip line 1, the second microstrip line 2, and the third microstrip line 3; each terminal open-circuit single-frequency bandpass loop filter has two couplings path, wherein, the first coupling path is the coupling part where the second microstrip line 2 and the fifth microstrip line 5 are parallel up and down; the second coupling path is the coupling part where the third microstrip line 3 and the sixth microstrip line 6 are parallel up and down part.

 倍。即构成一个典型的威尔金森功率分配器。  When the U-shaped half-wavelength resonator resonates in the power splitter integrated with a single-frequency bandpass filter, the signal at the input end and the signal at the output end of the open-circuit single-frequency bandpass loop filter have a phase shift of about -90°. The open-terminated single-frequency bandpass loop filter shown in Figure 2a consists of two U-shaped half-wavelength resonators. When the U-shaped half-wavelength resonator resonates, standing waves exist on the U-shaped half-wavelength resonator. When a standing wave propagates through a voltage antinode, the phase shifts by -180°. Between every two antinodes, the phase remains constant. The two coupling paths shown in Fig. 2a are labeled as the first coupling path and the second coupling path, respectively. Letters A to E designate in order the corresponding nodes of the first coupling path from the input port to the output port. In the first coupling path, point B is a voltage antinode with a -180° phase shift. Since there is no voltage node between points B and C, the phase shift at point C is also -180°. Next, considering that the phase shift of the signal on the open coupled line is -270°, the phase shift of the signal at point D is -90°. Then, the phase shift of the signal at point E is also -90°. The second coupling path has exactly the same analysis as the first coupling path. The points A' to E' are the nodes of the second coupling path. The phase offset of the E and E' node signals is the same. Therefore, the output port signal has a phase shift of approximately -90° with respect to the input port signal. Figure 2b is a transfer characteristic and phase simulation curve of a band-pass filter. It can be seen that there is a -91° phase offset at the signal center frequency of 1.8GHz, which reflects the -90° phase offset characteristic of the filter. It is precisely because the filter has a phase shift characteristic of -90°, so it can be used to replace the quarter-wavelength transmission line used in the traditional power divider to realize the function of impedance transformation. Therefore, when the input impedance of the power divider integrated with a single-frequency band-pass filter is the same as the output impedance, the input and output impedance of each open-circuit single-frequency band-pass loop filter is that of the power divider integrated with a single-frequency band-pass filter input impedance or output impedance of

times. That is to constitute a typical Wilkinson power divider.

Example

The structure of the power divider integrating a single-frequency bandpass filter is shown in Figure 1, and the relevant dimensions are shown in Figure 3 below. The thickness of the dielectric substrate is 0.63mm, and the relative permittivity is 6.15. The isolation element connected between the open ends of the two open-terminated single-frequency bandpass loop filters consists of a 500-ohm resistor and a 39-nanohenry inductance element to enhance isolation. As shown in Figure 3, the size parameters of each microstrip line of the terminal open-circuit single-frequency bandpass loop filter are as follows: the electrical length θ ₁ of the third microstrip line 3 is 61.3°, the open circuit end of the third microstrip line 3 is connected to the sixth The electrical length θ ₂ of the interval between the microstrip lines 6 is 54°, and the electrical length θ ₃ of the fourth microstrip line 4 is 45°. The respective electrical lengths of these microstrip lines are selected to obtain the desired input and output impedance characteristics, in-band transmission characteristics, and out-of-band attenuation characteristics.

Fig. 4a is the actual measurement result of the transmission characteristics of a power divider integrated with a single-frequency band-pass filter designed according to the above parameters; the horizontal axis in the transmission characteristic graph represents the frequency, and the vertical axis represents the transmission characteristic amplitude, where S ₁₁ Indicates the return loss of the input port of the power divider integrated with a single-frequency bandpass filter, S ₂₁ indicates the insertion loss from the first output port to the input port when the input port is matched, and S ₃₁ indicates that when the input port is matched, from The insertion loss from the second output port to the input port; the actual measurement is done using an E5071C network analyzer. It can be seen from the actual measurement results that the actual measured insertion loss curves S ₂₁ and S ₃₁ basically coincide, and the center frequency of the passband is at At 1.78GHz, the measured 1dB relative bandwidth is 10.1%, and the measured insertion loss S ₂₁ and S ₃₁ including the SMA connector at the center frequency of 1.78GHz are both -3.9dB. Due to the integration of the filter, the power insertion loss of the integrated single-band bandpass filter is slightly greater than that of a standard power splitter. In the passband, the return loss S ₁₁ of the input port of the power divider integrated with a single-frequency bandpass filter is higher than -14dB, and there is a transmission zero point on both sides of the passband, which greatly improves the filtering in the power divider The roll-off characteristic of the function. Fig. 4 b is the actual measurement result of the transfer characteristic curve of a power divider integrated with a single-frequency band-pass filter designed according to the above parameters; the horizontal axis in the transfer characteristic graph represents the frequency, and the vertical axis represents the transfer characteristic, wherein, S22 represents the return loss curve of the first output port, and S23 represents the isolation coefficient between the first output port and the second output port. The actually measured return loss S ₂₂ of the first output port is higher than -15dB; at the operating frequency point, the actually measured isolation factor between the first output port and the second output port is -37dB.

The actual measurement results of the embodiment show that the device of the present invention has two functions, not only can distribute the input energy equally, but also can screen out the required frequency band. the

The above is only a preferred example of the utility model, and is not intended to limit the utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the utility model shall be included in this utility model. within the scope of protection of utility models. the

Claims (6)

1. A power divider integrating a single-frequency bandpass filter, including an upper microstrip structure, an isolation element, an intermediate dielectric substrate, and a lower grounded metal plate. The upper microstrip structure and isolation elements are attached to the upper surface of the intermediate dielectric plate, and the middle The lower surface of the layer dielectric plate is grounded metal; it is characterized in that: the upper layer microstrip structure includes two terminal open-circuit single-frequency band-pass loop filters, and the two terminal open-circuit single-frequency band-pass loop filters have the same structure and are arranged in a symmetrical structure up and down , the two open-ended single-frequency band-pass loop filters share one input port as the input port of the power divider integrated with single-frequency band-pass filter, and the output ports of the two open-ended single-frequency band-pass loop filters serve as the integrated single-frequency band-pass filter. The two output ports of the filter's power divider. 2. according to the described power splitter of claim 1 integrated single-frequency band-pass filter, it is characterized in that the terminal open-circuit single-frequency band-pass loop filter that is positioned at top is made up of two U-shaped half-wavelength resonator couplings; Two U-shaped The structure of the half-wavelength resonator is exactly the same, wherein the U-shaped half-wavelength resonator connected to the input port is composed of the second microstrip line, the first microstrip line and the third microstrip line connected in sequence, the first microstrip line and the second microstrip line The intersection of the three microstrip lines is connected to the input port, and the U-shaped half-wavelength resonator connected to the first output port is composed of the fifth microstrip line, the fourth microstrip line and the sixth microstrip line, and the fourth microstrip line The intersection of the strip line and the fifth microstrip line is connected to the first output port; one end of the isolation element is connected to the open end of the sixth microstrip line of the open-ended single-frequency bandpass loop filter located above, and the other end is connected to the open circuit end of the sixth microstrip line located below The open-ended single-band bandpass loop filter is connected to the open-ended end of the corresponding microstrip line. 3. according to the described power splitter of claim 2 integrated single-frequency band-pass filter, it is characterized in that the length L of U-shaped half-wavelength resonator is the wavelength corresponding to the resonant frequency f of described terminal open-circuit single-frequency band-pass loop filter 1/2 of λ ; wherein, L is the actual length of the microstrip line; the actual length L of the microstrip line is the sum of the lengths of the first microstrip line, the second microstrip line and the third microstrip line. 4. The power splitter integrated with the single-frequency bandpass filter according to claim 2 is characterized in that each open-ended single-frequency bandpass loop filter has two coupling paths, wherein the first coupling path is the second microstrip line and the fifth microstrip line parallel to the upper and lower coupling parts, and the second coupling path is the third microstrip line and the sixth microstrip line parallel coupling part up and down. 5. according to the described power divider of claim 2 integrated single-frequency bandpass filter, it is characterized in that the input impedance of the power divider integrated single-frequency bandpass filter is identical with output impedance, each terminal open circuit single-frequency bandpass ring The input and output impedance of the filter is the input impedance or output impedance of the power divider integrated with the single frequency bandpass filter

times. 6. The power divider integrated with a single-frequency bandpass filter according to any one of claims 2 to 5, wherein the isolation element is a resistor, a capacitor or an inductor.

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