A compact Gysel filtered power divider

Abstract

The application discloses a compact equal-division Gysel filtering power divider, which comprises an upper layer microstrip structure, an isolation component, a middle layer dielectric plate and a lower layer ground metal plate; the upper layer microstrip structure comprises a filtering impedance transformation component and an isolation network; the isolation network comprises a high impedance microstrip component, an inductance component, a capacitance component and a resistance component; an input port of the filtering impedance transformation component serves as an input end of the device; output ports of the filtering impedance transformation component are connected with the high impedance microstrip component; the capacitance component is connected between the high impedance microstrip components; the inductance component and the resistance component are parallel to the ends of the high impedance microstrip component; and the resistance component is grounded. The compact equal-division Gysel filtering power divider is flexible in adjustment and simple in structure; in addition to the advantages of high power application of the Gysel power divider, the volume is further simplified, and the miniaturization of a communication system is facilitated.

Description

Technical Field

[0001] This application relates to the field of power distribution device technology, and in particular to a compact Gysel filter power divider with integrated filtering function that can be applied to radio frequency front-end circuits. Background Technology

[0002] Power dividers and filters, as important components of RF front-end devices, have always been a hot research topic. With the continuous development of wireless communication technology, the requirements for miniaturization and high performance of RF front-end systems are becoming increasingly stringent. Integrating filters and power dividers in a unified design can significantly simplify circuit structures and reduce insertion loss, which has high application value.

[0003] Traditional design methods involve designing the two devices separately and then connecting them using matching devices. This approach results in significant size and losses. Later, designs combining the input and output matching of the two devices emerged, eliminating the need for a separate matching network, but this simplification is limited. Currently, the mainstream design method utilizes a filter structure with 90° phase characteristics to replace the quarter-wavelength microstrip line in the power divider, achieving a combination of the two functions. Using this design approach, many researchers have designed various filter power dividers combining Gysel and Wilkinson topologies.

[0004] Current power dividers are designed based on Gysel and Wilkinson power divider topologies. Wilkinson power dividers, when divided equally, are smaller and easier to design than Gysel dividers. However, because their internal isolation resistors are not grounded, they accumulate heat and are not suitable for high-power applications. Gysel power dividers, on the other hand, have two grounded isolation resistors, which help dissipate heat and enable high-power operation. Methods to further reduce the size of Gysel power dividers while maintaining their heat dissipation capabilities are rare, and there is still no suitable solution for designing fusion filters. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a compact Gysel power divider with integrated filtering functionality that can be applied to RF front-end circuits. The aim is to further reduce the size of the Gysel power divider while ensuring its heat dissipation capability. By introducing lumped components, the size of the Gysel power divider is significantly reduced, achieving high-power applications with a size almost the same as a Wilkinson structure. Furthermore, its device bandwidth can be flexibly adjusted.

[0006] This invention discloses a compact, equally divided Gysel filter power divider. The equally divided Gysel filter power divider includes an upper microstrip structure and isolation components, an intermediate dielectric substrate, and a lower ground metal plate. The upper microstrip structure and isolation components are attached to the upper surface of the intermediate dielectric substrate, and the lower ground metal plate is attached to the lower surface of the intermediate dielectric substrate. The upper microstrip structure includes a filter impedance transformation component and an isolation network. The isolation network includes a high-impedance microstrip component, an inductor component, a capacitor component, and a resistor component. The input port of the filter impedance transformation component serves as the input terminal of the device, and the output port of the filter impedance transformation component is connected to the high-impedance microstrip component. The components include capacitor components connected between high-impedance microstrip components, inductor components and resistor components parallel to the ends of high-impedance microstrip components, grounded resistor components, isolation components connected to high-impedance microstrip components in the upper microstrip structure, and a filter impedance transformation component comprising two filter impedance transformers with the same equivalent impedance and symmetrically coupled to form an upper half-impedance transformer and a lower half-impedance transformer. The upper half-impedance transformer is composed of two half-wavelength resonators coupled together, and the length L of the half-wavelength resonator is half the wavelength λ corresponding to the resonant frequency f of the filter impedance transformer.

[0007] A further technical solution of the present invention is that the filter impedance converter has a 90° phase characteristic within the passband.

[0008] A further technical solution of the present invention is as follows: the high-impedance microstrip assembly in the isolation network consists of two high-impedance microstrip lines, the inductor assembly consists of two inductors, the capacitor assembly consists of two capacitors, and the resistor assembly consists of two resistors. The two filter impedance converters share an input port P1 as the input terminal of the device, and P2 and P3 are used as output ports respectively. The two high-impedance microstrip lines are connected to the output ports P2 and P3 respectively. The capacitors are connected between the two high-impedance microstrip lines. The inductors and resistors are parallel to the ends of the high-impedance microstrip lines, and the resistors are grounded.

[0009] A further technical solution of the present invention is that the two high-impedance microstrip lines have the same characteristic impedance and electrical length.

[0010] A further technical solution of the present invention is: the upper half-impedance transformer / lower half-impedance transformer is composed of two half-wavelength resonators coupled together to form a first resonator and a second resonator. The upper side of the first resonator includes a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, and a seventh microstrip line. The lower side of the first resonator is symmetrically placed with respect to the first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line, the fifth microstrip line, the sixth microstrip line, and the seventh microstrip line. The second resonator is composed of a microstrip structure that is symmetrical to the center of the first resonator.

[0011] A further technical solution of the present invention is: the coupling between the seventh microstrip line in the first resonator and the microstrip line corresponding to the seventh microstrip line in the second resonator is called the first coupling structure, and the coupling between the microstrip line symmetrical to the seventh microstrip line on the lower side of the first resonator and the corresponding microstrip line in the second resonator is called the second coupling structure. The equivalent impedance and bandwidth are controlled by adjusting the coupling strength and port position of the first coupling mechanism and the second coupling structure.

[0012] A further technical solution of the present invention is as follows: the isolation network structure includes a first branch line and a lower half symmetrical to the first branch line. The first branch line includes an eighth microstrip line and a ninth microstrip line connected to one end of the eighth microstrip line. A first capacitor is connected in parallel between the other end of the ninth microstrip line and the lower half of the microstrip line symmetrical to the ninth microstrip line. A first inductor is parallel to the ninth microstrip line and connected to the end of the ninth microstrip line. A second inductor is parallel to the lower half of the microstrip line symmetrical to the ninth microstrip line and connected to the end of the lower half of the microstrip line symmetrical to the ninth microstrip line. A second capacitor is connected in parallel to the other ends of the first inductor and the second inductor. A first resistor and a second resistor are parallel to the first inductor and the second inductor and connected to the ends of the first inductor and the second inductor, respectively. The other ends of the first resistor and the second resistor are both grounded.

[0013] A further technical solution of the present invention is that the first branch line and its symmetrical portion have the same electrical length.

[0014] This invention provides a compact, equally divided Gysel filter power divider. It replaces the quarter-wavelength impedance transformer in the Gysel power divider with a filter exhibiting a 90° phase shift within the passband. The equivalent input and output impedances can be adjusted by modifying the port positions and coupling strength of the resonators. Furthermore, the isolation network in the classic Gysel topology is modified, replacing the four quarter-wavelength microstrip lines with a combination of lumped devices and microstrip lines. This significantly reduces the device size and improves space utilization. Finally, the introduction of two transmission zeros near the passband enhances the frequency selectivity of the signal. This structure integrates a filter structure into the power divider design, enabling simultaneous power distribution and frequency selection. By adjusting the coupling strength and port positions between the resonators in the upper or lower half of the impedance transformer, the equivalent impedance and bandwidth can be flexibly adjusted. Adjusting the inductor and capacitor values ​​allows for adjustment of the first branch line length, thus enabling a more compact structure by adjusting the microstrip line length according to the filter size. The design is relatively simple and the adjustments are flexible. It retains the advantage of Gysel filters operating in high-power scenarios while significantly reducing its size. Furthermore, the two transmission zeros near the passband provide excellent frequency selectivity. In summary, the beneficial effects of this invention are:

[0015] (1) Flexible adjustment and simple structure;

[0016] (2) Compared with existing power dividers, it retains the advantages of high-power applications of Gysel power dividers and further simplifies the size, which helps to miniaturize communication systems.

[0017] (3) It has two transmission zeros, which ensures the frequency selectivity of the signal. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the planar structure of the compact equally divided Gysel filter power divider according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the planar structure of the isolation network of the compact equally divided Gysel filter power divider according to an embodiment of the present invention;

[0020] Figure 3 This is a transmission characteristic curve of the compact equally divided Gysel filter power divider according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the output return loss and isolation coefficient of the compact equally divided Gysel filter power divider according to an embodiment of the present invention. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the drawings, not the entire structure.

[0023] Furthermore, the terms "first," "second," "third," etc., may be used herein to describe various directions, actions, steps, or elements, but these directions, actions, steps, or elements are not limited by these terms. These terms are only used to distinguish a first direction, action, step, or element from another direction, action, step, or element. For example, without departing from the scope of this application, a first microstrip line may be referred to as a second microstrip line, and similarly, a second microstrip line may be referred to as a first microstrip line. Both the first microstrip line and the second microstrip line are microstrip lines, but they are not the same microstrip line. The terms "first," "second," etc., should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] like Figure 1 and Figure 2 As shown, the present invention proposes a compact, equally divided Gysel filter power divider, and provides the following embodiments:

[0025] See Figure 1 , Figure 2The compact Gysel filter power divider comprises an upper microstrip structure and isolation components, an intermediate dielectric substrate, and a lower ground metal plate. The upper microstrip structure and isolation components are attached to the upper surface of the intermediate dielectric substrate, and the lower ground metal plate is attached to the lower surface of the intermediate dielectric substrate. The upper microstrip structure includes a filter impedance transformation component and an isolation network. The isolation network includes a high-impedance microstrip component, an inductor component, a capacitor component, and a resistor component. The input port of the filter impedance transformation component serves as the input terminal of the device, and the output port of the filter impedance transformation component is connected to the high-impedance microstrip component. The capacitor components are connected between the high-impedance microstrip components, and the inductor components... The resistor component is parallel to the end of the high-impedance microstrip component, and the resistor component is grounded. The isolation component is connected to the high-impedance microstrip component in the upper microstrip structure. The filter impedance transformation component includes two filter impedance transformers with the same equivalent impedance to achieve equal power distribution. The two filter impedance transformers are symmetrically coupled with the same equivalent impedance to form an upper half-impedance transformer and a lower half-impedance transformer. The upper half-impedance transformer is composed of two half-wavelength resonators coupled together. The length L of the half-wavelength resonator is half the wavelength λ corresponding to the resonant frequency f of the filter impedance transformer, and the length L is the actual microstrip line length. The filter impedance transformer has a 90° phase characteristic within its passband.

[0026] See Figure 1 , Figure 2 In the isolation network, the high-impedance microstrip assembly consists of two high-impedance microstrip lines, the inductor assembly consists of two inductors, the capacitor assembly consists of two capacitors, and the resistor assembly consists of two resistors. The two filter impedance transformers share an input port P1 as the input terminal of the device, and P2 and P3 are used as output ports respectively. The equivalent impedances of the two impedance transformers are the same to achieve the effect of equal power distribution. The two high-impedance microstrip lines are connected to the output ports P2 and P3 respectively. The characteristic impedances and electrical lengths of the two high-impedance microstrip lines are the same. The capacitors are connected between the two high-impedance microstrip lines. The inductors and resistors are parallel to the ends of the high-impedance microstrip lines, and the resistors are grounded.

[0027] See Figure 1 , Figure 2The upper half-impedance transformer / lower half-impedance transformer consists of two half-wavelength resonators coupled together to form a first resonator and a second resonator. The upper side of the first resonator includes a first microstrip line 4, a second microstrip line 5, a third microstrip line 6, a fourth microstrip line 7, a fifth microstrip line 8, a sixth microstrip line 9, and a seventh microstrip line 10. The lower side of the first resonator is symmetrically placed with respect to the first microstrip line 4, the second microstrip line 5, the third microstrip line 6, the fourth microstrip line 7, the fifth microstrip line 8, the sixth microstrip line 9, and the seventh microstrip line 10. The second resonator consists of a microstrip structure that is symmetrical about the center of the first resonator.

[0028] The coupling between the seventh microstrip line 10 in the first resonator and the microstrip line corresponding to the seventh microstrip line 10 in the second resonator is called the first coupling structure. The coupling between the microstrip line symmetrical to the seventh microstrip line 10 on the lower side of the first resonator and the corresponding microstrip line in the second resonator is called the second coupling structure. The equivalent impedance and bandwidth are controlled by adjusting the coupling strength and port position of the first coupling mechanism and the second coupling structure.

[0029] See Figures 1-2 The isolation network structure includes a first branch line 3, a lower half symmetrical to the first branch line 3, and a lumped device network between the first branch line 3 and its lower half. The first branch line 3 includes an eighth microstrip line 11 and a ninth microstrip line 12 connected to one end of the eighth microstrip line 11. Figure 2 A first capacitor is connected in parallel between the other end of the ninth microstrip line and the lower half of the microstrip line symmetrical to the ninth microstrip line. A first inductor is parallel to the ninth microstrip line and connected to the end of the ninth microstrip line. A second inductor is parallel to the lower half of the microstrip line symmetrical to the ninth microstrip line and connected to the end of the lower half of the microstrip line symmetrical to the ninth microstrip line. A second capacitor is connected in parallel to the other ends of the first inductor and the second inductor. A first resistor and a second resistor are parallel to the first inductor and the second inductor and connected to the ends of the first inductor and the second inductor, respectively. The other ends of the first resistor and the second resistor are both grounded.

[0030] The first branch line 13 and its symmetrical part have the same electrical length. The electrical length can be adjusted according to the actual size of the filter and the actual needs of the system design, which can improve the utilization of space.

[0031] The compact Gysel power divider of this invention allows for flexible adjustment of the equivalent impedance and bandwidth by adjusting the coupling strength and port positions between the resonators in the upper or lower half of the impedance transformer. Adjusting the inductor and capacitor values ​​allows for adjustment of the length of the first branch line, thus enabling a more compact structure by adjusting the microstrip line length according to the filter size. The design is relatively simple and the adjustments are flexible, retaining the advantages of Gysel filters in high-power applications while significantly reducing its size. Furthermore, the two transmission zeros near the passband provide excellent frequency selectivity for the signal.

[0032] The compact Gysel power divider of this invention has a half-wavelength resonator whose length L is half the wavelength λ corresponding to the resonant frequency f of the filter impedance transformer. This length L is the actual microstrip line length in the filter impedance transformer. The first branch line and its symmetrical portion have the same electrical length. The electrical length can be adjusted according to the actual size of the filter and the actual needs of the system design, thereby improving space utilization.

[0033] Example

[0034] The structure of a compact, equally divided Gysel filter power divider is as follows: Figure 1 As shown, the thickness of the dielectric substrate is 0.81 mm and the relative permittivity is 3.38.

[0035] Figure 3 and Figure 4 The figures show simulation and test results of the transmission characteristics of a compact, equally divided Gysel power divider designed based on the above conditions. The horizontal axis represents frequency, and the vertical axis represents the transmission characteristics in dB. Figure 3 In the diagram, S11 represents the input return loss of the dual-frequency equal-segment Gysel power divider, and S21 and S31 represent the insertion loss from the first output port P2 and the second output port P3 to the input port P1 when the input port P1 is matched. The measured results show that the compact equal-segment Gysel power divider operates at a frequency of 2.08 GHz; the input return loss S11 is below -15 dB in the passband near the operating frequency, with a minimum of -16.75 dB; the insertion loss curves S21 and S31 basically overlap, reaching -4.02 dB at the operating frequency of approximately 2.08 GHz; and there are two transmission zeros near the passband, enhancing the frequency selectivity of the power divider. Figure 4In the diagram, S22 and S33 represent the output return losses of the first output port P2 and the second output port P3, respectively, and S23 represents the isolation coefficient of the first output port P2 and the second output port P3. Actual test results show that the output return loss curves S22 and S33 basically overlap, and are below -15dB in the passband near the operating frequency, exhibiting slight overcoupling. This also makes the actual bandwidth slightly larger than the simulation result. The actual bandwidth is -16.7dB at the 2.08GHz operating frequency, with a minimum of -21.04dB. The isolation coefficient S23 is generally below -15dB in the passband near the operating frequency, with a minimum of -20.1dB at the 2.08GHz operating frequency and a minimum of -23.3dB. Furthermore, the final physical size is approximately 0.15λ. g *0.27λ g This device not only significantly reduces the size of the Gysel filter power divider, but also allows for modification of the microstrip lines in the isolation section to suit the actual filter size, resulting in a substantial improvement in space utilization. Furthermore, it retains the excellent heat dissipation characteristics of the Gysel filter power divider, enabling its application in high-power scenarios.

[0036] The test results of the embodiments show that the above-described compact equal-division Gysel filter power divider can achieve equal power distribution and filtering functions.

[0037] The compact, equally divided Gysel filter power divider provided in the above embodiments replaces the quarter-wavelength impedance transformer in the Gysel power divider with a filter having a 90° phase shift characteristic within the passband. Its equivalent input and output impedance can be adjusted by changing the port positions and coupling strength of the resonators. Furthermore, the isolation network in the classic Gysel topology is modified, replacing the four quarter-wavelength microstrip lines with a combination of lumped devices and microstrip lines. This significantly reduces the device size and improves space utilization. Finally, the introduction of two transmission zeros near the passband improves the frequency selectivity of the signal. This structure integrates the filter structure into the power divider design, enabling it to simultaneously achieve power distribution and frequency selection. By adjusting the coupling strength and port positions between the resonators in the upper or lower half of the impedance transformer, the equivalent impedance and bandwidth of the structure can be flexibly adjusted. Adjusting the inductor and capacitor values ​​can adjust the length of the first branch line, thereby allowing for a more compact structure by appropriately adjusting the microstrip line length according to the filter size. The design is relatively simple and the adjustments are flexible. It retains the advantages of Gysel filters in high-power applications while significantly reducing its size. Furthermore, the two transmission zeros near the passband provide excellent frequency selectivity. In summary, the advantages of this invention are: flexible adjustment and simple structure; compared to existing power dividers, it retains the advantages of Gysel power dividers for high-power applications while further simplifying the size, contributing to the miniaturization of communication systems; and the two transmission zeros ensure frequency selectivity of the signal.

[0038] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A compact, equally divided Gysel filter power divider, characterized in that, The equal-division Gysel filter power divider includes an upper microstrip structure and an isolation network, an intermediate dielectric substrate, and a lower ground metal plate. The upper microstrip structure and isolation network are attached to the upper surface of the intermediate dielectric substrate, and the lower ground metal plate is attached to the lower surface of the intermediate dielectric substrate. The upper microstrip structure includes a filter impedance transformation component. The isolation network includes a high-impedance microstrip component and isolation components. The isolation components include inductor components, capacitor components, and resistor components. The isolation components are connected to the high-impedance microstrip component. The input port of the filter impedance transformation component serves as the input terminal of the device, and the output port is connected to the high-impedance microstrip component. The filter impedance transformation component includes two filter impedance transformers. The two filter impedance transformers have the same equivalent impedance and are symmetrically coupled to form an upper half-impedance transformer and a lower half-impedance transformer. The upper half-impedance transformer is composed of two half-wavelength resonators coupled together. The length L of the half-wavelength resonator is half of the wavelength λ corresponding to the resonant frequency f of the filter impedance transformer. In the isolated network, the high-impedance microstrip assembly consists of two high-impedance microstrip lines, the inductor assembly consists of two inductors, the capacitor assembly consists of two capacitors, and the resistor assembly consists of two resistors. The two filter impedance transformers share an input port P1 as the input terminal of the device. One filter impedance transformer uses P2 as the output port, and the other uses P3 as the output port. One of the two high-impedance microstrip lines is connected to the output port P2, and the other is connected to the output port P3. The capacitor is connected between the two high-impedance microstrip lines. The inductors and resistors are parallel to the ends of the high-impedance microstrip lines, and the resistors are grounded.

2. The equally divided Gysel filter power divider according to claim 1, characterized in that, The filter impedance converter has a 90° phase characteristic within its passband.

3. The equally divided Gysel filter power divider according to claim 1, characterized in that, The two high-impedance microstrip lines have the same characteristic impedance and electrical length.

4. The equally divided Gysel filter power divider according to claim 1, characterized in that, The upper half-impedance transformer consists of two half-wavelength resonators coupled together to form a first resonator and a second resonator. The upper side of the first resonator includes a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a sixth microstrip line, and a seventh microstrip line. The lower side of the first resonator is symmetrically placed with the first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line, the fifth microstrip line, the sixth microstrip line, and the seventh microstrip line. The second resonator consists of a microstrip structure that is symmetrical to the center of the first resonator.

5. The equally divided Gysel filter power divider according to claim 4, characterized in that, The coupling between the seventh microstrip line in the first resonator and the corresponding microstrip line in the second resonator is called the first coupling structure. The coupling between the microstrip line symmetrical to the seventh microstrip line on the lower side of the first resonator and the corresponding microstrip line in the second resonator is called the second coupling structure. The equivalent impedance and bandwidth can be controlled by adjusting the coupling strength and port position of the first and second coupling structures.

6. The equally divided Gysel filter power divider according to claim 1, characterized in that, The isolation network structure includes a first branch line and a lower half symmetrical to the first branch line. The first branch line includes an eighth microstrip line and a ninth microstrip line connected to one end of the eighth microstrip line. A first capacitor is connected in parallel between the other end of the ninth microstrip line and the lower half of the microstrip line symmetrical to the ninth microstrip line. A first inductor is parallel to the ninth microstrip line and connected to the end of the ninth microstrip line. A second inductor is parallel to the lower half of the microstrip line symmetrical to the ninth microstrip line and connected to the end of the lower half of the microstrip line symmetrical to the ninth microstrip line. A second capacitor is connected in parallel to the other ends of the first and second inductors. A first resistor and a second resistor are parallel to the first and second inductors. The first resistor is connected to the end of the first inductor, and the second resistor is connected to the end of the second inductor. The other ends of both the first and second resistors are grounded.

7. The equally divided Gysel filter power divider according to claim 6, characterized in that, The first branch and its symmetrical portion have the same electrical length.

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