Bandwidth filtering power divider

Abstract

The invention provides a bandwidth filtering power divider, and relates to the technical field of communication devices, the bandwidth filtering power divider comprises a main branch, a reference branch, an input port, a first output port and a second output port; the main branch comprises a main transmission line, a main stepped impedance open line, a main symmetrical open-circuit coupling line and a main black box which are electrically connected in sequence; the reference branch comprises a reference transmission line, a reference stepped impedance open line, a reference symmetric open-circuit coupling line and a reference black box which are electrically connected in sequence; the main black box and the reference black box are used for controlling the phase difference between the signal of the first output port and the signal of the second output port, and the adjustment range of the phase difference is 0-360 degrees. The main black box and the reference black box are matched with each other, so that the phase difference adjustment range supported by the power divider can be expanded to a full range interval from 0 degree to 360 degrees.

Description

Technical Field

[0001] The present application relates to the technical field of communication devices, and in particular to a bandwidth filtering power divider. Background Art

[0002] The power divider with filtering function can not only divide the input power into two or more paths according to the predetermined power distribution ratio, but also provide out-of-band suppression. It has been widely used in the feeding network of antenna arrays and various modern communication systems.

[0003] In the topology design of the power divider provided by the related art, the phase difference adjustment range between different channels is small. Summary of the invention

[0004] The purpose of the present application is to provide a bandwidth filtering power divider, which is used to solve the technical problem that the phase difference adjustment range of the power divider provided by the related art is insufficient.

[0005] In a first aspect, the present application provides a bandwidth filtering power splitter, the bandwidth filtering power splitter comprising: a main branch, a reference branch, an input port, a first output port, and a second output port;

[0006] The main branch includes a main transmission line, a main step impedance open circuit, a main symmetrical open coupling circuit and a main black box;

[0007] The reference branch includes a reference transmission line, a reference step impedance open line, a reference symmetrical open coupling line and a reference black box;

[0008] The input port is electrically connected to the input end of the main transmission line, the output end of the main transmission line is electrically connected to the input end of the main step impedance open circuit, the output end of the main transmission line is electrically connected to the input end of the main symmetrical open-circuit coupling circuit, the output end of the main symmetrical open-circuit coupling circuit is electrically connected to the input end of the main black box, and the output end of the main black box is electrically connected to the first output port;

[0009] The input port is electrically connected to the input end of the reference transmission line, the output end of the reference transmission line is electrically connected to the input end of the reference step impedance open line, the output end of the reference transmission line is electrically connected to the input end of the reference symmetrical open coupled line, the output end of the reference symmetrical open coupled line is electrically connected to the input end of the reference black box, and the output end of the reference black box is electrically connected to the second output port;

[0010] The main black box and the reference black box are used to control the phase difference between the signal of the first output port and the signal of the second output port, and the adjustment range of the phase difference is 0° to 360°.

[0011] In one embodiment, the main black box includes a main coupling line and a main short stub, and the main coupling line and the main short stub are electrically connected;

[0012] The reference black box includes a reference coupling line and a reference stub, and the reference coupling line and the reference stub are electrically connected.

[0013] In one embodiment, the main stub is a short-circuited stub and the reference stub is an open-circuited stub;

[0014] or,

[0015] The main stub is an open stub and the reference stub is an open stub.

[0016] In one embodiment, the bandwidth filter power divider further comprises a phase delay line;

[0017] The output end of the main symmetrical open-circuit coupling circuit is electrically connected to the input end of the main black box, the output end of the main black box is electrically connected to the input end of the phase delay line, and the output end of the phase delay line is electrically connected to the first output port.

[0018] In one embodiment, the bandwidth filtering power divider further includes the first isolation resistor, wherein a first end of the first isolation resistor is electrically connected to the main step impedance open circuit, and a second end of the first isolation resistor is electrically connected to the reference step impedance open circuit;

[0019] and / or,

[0020] The bandwidth filtering power divider also includes the second isolation resistor, a first end of the second isolation resistor is electrically connected to the output end of the main transmission line, and a second end of the second isolation resistor is electrically connected to the output end of the reference transmission line.

[0021] In one embodiment, when the bandwidth filter power divider includes the first isolation resistor and the second isolation resistor, and the resistance value of the first isolation resistor is a first target resistance value, and the resistance value of the second isolation resistor is a second target resistance value, the isolation of the output port of the bandwidth filter power divider is maximum, wherein the first target resistance value and the second target resistance value are determined based on the isolation bandwidth.

[0022] In one embodiment, the first target resistance value and the second target resistance value are determined based on a preset expression and an isolation bandwidth;

[0023] Among them, the preset expression is used to represent the mapping relationship between the resistance value of the first isolation resistor, the resistance value of the second isolation resistor and the bandwidth value of the isolation bandwidth, and the preset expression is obtained based on the difference between the even-mode equivalent circuit of the main branch and the odd-mode equivalent circuit of the main branch, and the difference between the even-mode equivalent circuit of the reference branch and the odd-mode equivalent circuit of the reference branch.

[0024] In one embodiment, the electrical length of any one transmission line in the bandwidth filter power divider is 90 degrees at the center frequency of the bandwidth filter power divider, wherein the transmission line is a transmission line connecting two devices in the bandwidth filter power divider.

[0025] and / or,

[0026] The wavelength of the main step impedance open line is half of the wavelength at the center frequency of the bandwidth filter power divider, and the wavelength of the reference step impedance open line is half of the wavelength at the center frequency of the bandwidth filter power divider.

[0027] In one embodiment, the filtering function of the bandwidth filtering power divider is a generalized Chebyshev function, and the response of the filtering function of the bandwidth filtering power divider is determined based on a main out-of-band transmission zero point and a reference out-of-band transmission zero point, wherein the main out-of-band transmission zero point is the out-of-band transmission zero point corresponding to the main step impedance open line, and the reference out-of-band transmission zero point is the out-of-band transmission zero point corresponding to the reference step impedance open line.

[0028] In one embodiment, the phase slope of the main branch is the same as the phase slope of the reference branch.

[0029] In the present application, a main black box is set in the main branch and a reference black box is set in the reference branch, and the main black box and the reference black box cooperate with each other, so that the user can flexibly adjust the phase difference of different signals output by the first output port and the second output port by adjusting the device settings in the main black box and the reference black box, thereby expanding the phase difference adjustment range supported by the power divider to the full range of 0° to 360°, and supporting a wider working bandwidth. On the premise of satisfying the constant power allocation ratio within the band, the circuit design of the main branch and the circuit design of the reference branch are supported to be independent of each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of a bandwidth filtering power divider provided in an embodiment of the present application;

[0031] Figure 2 is a schematic diagram of an equivalent circuit of a bandwidth filtering power divider provided in an embodiment of the present application;

[0032] Figure 3 yes Figure 2 Schematic diagram of the equivalent circuit of the filter branch;

[0033] Figure 4 It is a theoretical and circuit simulation frequency response of a power divider provided in an embodiment of the present application;

[0034] Figure 5 It is a theoretical result of the circuit model of different types of short stubs at different bandwidths provided by the embodiments of the present application;

[0035] FIG. 6( a ) is a theoretical result of a circuit model with different bandwidths under a given power allocation ratio provided in an embodiment of the present application;

[0036] FIG6( b ) is a theoretical result of a circuit model with different power allocation ratios under a given bandwidth provided by an embodiment of the present application;

[0037] Figure 7 is a response curve of the isolation of a power divider provided in an embodiment of the present application;

[0038] Figure 8(a) is a Figure 2 Schematic diagram of the simplified equivalent circuit;

[0039] FIG8( b ) is a schematic diagram of an equivalent even-mode circuit of the reference branch and the main branch in FIG8( a );

[0040] FIG8( c ) is a schematic diagram of an equivalent odd-mode circuit of the reference branch and the main branch in FIG8( a );

[0041] Fig. 9 It is a schematic diagram of the isolation bandwidth of a power divider provided in an embodiment of the present application changing with the zero point;

[0042] Fig.10 is a simulation curve of the isolation of the power divider when the transmission zero point is at different positions provided by the embodiment of the present application;

[0043] FIG. 11( a ) is a curve showing a change in phase difference under different bandwidths when the black box circuit types of the main branch and the reference instruction provided in an embodiment of the present application are the same;

[0044] FIG. 11( b ) is a curve showing a change in phase difference under different bandwidths when the black box circuit types of the main branch and the reference instruction provided in an embodiment of the present application are different;

[0045] FIG. 12( a ) is a curve showing a change in phase difference when the black box circuit types of the main branch and the reference instruction provided in an embodiment of the present application are both type I;

[0046] FIG12( b ) is a curve showing the change of the phase difference when the black box circuit types of the main branch and the reference instruction provided in the embodiment of the present application are Type I and Type II respectively. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] The present application embodiment provides a bandwidth filtering power divider, such as Figure 1 As shown, the bandwidth filtering power divider includes:

[0049] A main branch, a reference branch, an input port 30, a first output port 40 and a second output port 50;

[0050] The main branch includes a main transmission line 11, a main step impedance open circuit 12, a main symmetrical open coupling circuit 13 and a main black box 14;

[0051] The reference branch includes a reference transmission line 21, a reference step impedance open line 22, a reference symmetrical open coupling line 23 and a reference black box 24;

[0052] The input port 30 is electrically connected to the input end of the main transmission line 11, the output end of the main transmission line 11 is electrically connected to the input end of the main step impedance open line 12, the output end of the main transmission line 11 is electrically connected to the input end of the main symmetrical open-circuit coupling line 13, the output end of the main symmetrical open-circuit coupling line 13 is electrically connected to the input end of the main black box 14, and the output end of the main black box 14 is electrically connected to the first output port 40;

[0053] The input port 30 is electrically connected to the input end of the reference transmission line 21, the output end of the reference transmission line 21 is electrically connected to the input end of the reference step impedance open line 22, the output end of the reference transmission line 21 is electrically connected to the input end of the reference symmetrical open coupled line 23, the output end of the reference symmetrical open coupled line 23 is electrically connected to the input end of the reference black box 24, and the output end of the reference black box 24 is electrically connected to the second output port 50;

[0054] The main black box 14 and the reference black box 24 are used to control the phase difference between the signal of the first output port 40 and the signal of the second output port 50 , and the adjustment range of the phase difference is 0° to 360°.

[0055] The main transmission line 11 is used to transmit a signal branched from the input port 30 to the main step impedance open line 12, the main step impedance open line 12 is used to transmit the signal transmitted from the main transmission line 11 to the main symmetrical open coupling line 13, the main step impedance open line 12 is also used to provide a filtering function for the signal, the main symmetrical open coupling line 13 is used to transmit the signal transmitted from the main step impedance open line 12 to the main black box 14, and the main symmetrical open coupling line 13 is also used to provide interference suppression function for the signal to stabilize the transmission of the signal;

[0056] Similarly, the reference transmission line 21 is used to transmit a signal branched from the input port 30 to the reference step impedance open line 22, the reference step impedance open line 22 is used to transmit the signal transmitted from the reference transmission line 21 to the reference symmetrical open coupling line 23, the reference step impedance open line 22 is also used to provide filtering processing function for the signal, the reference symmetrical open coupling line 23 is used to transmit the signal transmitted from the reference step impedance open line 22 to the reference black box 24, and the reference symmetrical open coupling line 23 is also used to provide interference suppression function for the signal to stabilize the transmission of the signal.

[0057] The main black box 14 and the reference black box 24 cooperate with each other, so that the user can flexibly adjust the phase difference between the signal output by the main black box 14 and the signal output by the reference black box 24 by adjusting the device settings in the main black box 14 and the reference black box 24, thereby realizing the phase difference adjustment of different signals output by the first output port 40 and the second output port 50, so that the phase difference adjustment range supported by the power divider can be extended to the full range of 0° to 360°, and can support a wider working bandwidth, and under the premise of satisfying the constant power allocation ratio within the band, support the circuit design of the main branch and the circuit design of the reference branch to be independent of each other.

[0058] In one embodiment, the main black box 14 includes a main coupling line and a main short stub, and the main coupling line and the main short stub are electrically connected;

[0059] The reference black box 24 includes a reference coupling line and a reference stub, and the reference coupling line and the reference stub are electrically connected.

[0060] Among them, the main short stub can be an open short stub or a short short stub; similarly, the reference short stub can be an open short stub or a short short stub; in application, the specific types of the main short stub and the reference short stub can be adaptively selected according to needs.

[0061] In one embodiment, the bandwidth filter power divider further includes a phase delay line 70;

[0062] The output end of the main symmetrical open-circuit coupling circuit 13 is electrically connected to the input end of the main black box 14 , the output end of the main black box 14 is electrically connected to the input end of the phase delay line 70 , and the output end of the phase delay line 70 is electrically connected to the first output port 40 .

[0063] In this embodiment, the phase delay line 70 is provided to ensure that the numerical deviation between the actual phase difference and the expected phase difference between the signal of the first output port 40 and the signal of the second output port 50 is within a set fluctuation range.

[0064] Specifically, according to actual application requirements, by reasonably selecting the circuit type of the main black box 14, the circuit type of the reference black box 24 and the length of the delay line, the full phase difference of 0° to 360° can be well achieved.

[0065] Further, the main stub is a short-circuited stub and the reference stub is an open-circuited stub;

[0066] or,

[0067] The main stub is an open stub and the reference stub is an open stub.

[0068] Wherein, when the main stub is a short-circuited stub and the reference stub is an open-circuited stub, a wider phase shift range can be achieved, specifically 180° to 360°, and in this case the required delay line length is shorter.

[0069] In the case where the main stub is a short-circuited stub and the reference stub is an open-circuited stub, the signal output by the main branch and the signal output by the reference branch can obtain a better out-of-band suppression effect.

[0070] In one embodiment, when the main stub is an open stub, the maximum impedance of the main stub is less than or equal to 150 ohms;

[0071] In the case where the reference stub is an open stub, the maximum impedance of the reference stub is less than or equal to 150 ohms.

[0072] In this embodiment, for the case where the main short-circuit line or the reference short-circuit line is an open-circuit short-circuit line, its maximum impedance is set to be less than or equal to 150 ohms to avoid excessive impedance setting which will sharply increase the difficulty of short-circuit processing, so that the manufacturing cost of the bandwidth filtering power divider described in the present application is within a controllable range.

[0073] In one embodiment, the bandwidth filter power divider further includes a first isolation resistor 61, a first end of the first isolation resistor 61 is electrically connected to the main step impedance open line 12, and a second end of the first isolation resistor 61 is electrically connected to the reference step impedance open line 22;

[0074] The bandwidth filtering power divider further includes a second isolation resistor 62 , a first end of the second isolation resistor 62 is electrically connected to the output end of the main transmission line 11 , and a second end of the second isolation resistor 62 is electrically connected to the output end of the reference transmission line 21 .

[0075] In this embodiment, the first isolation resistor 61 and / or the second isolation resistor 62 are provided to isolate signals between different main branches and reference branches, thereby ensuring the independence and stability of the main branch output signal and the reference branch output signal.

[0076] In one example, when the bandwidth filtering power divider includes both the first isolation resistor 61 and the second isolation resistor 62, the first isolation resistor 61, the second isolation resistor 62, the main step impedance open circuit and the reference step impedance open circuit together constitute an isolation network, which can enable the first output port 40 and the second output port 50 to obtain a better signal isolation effect.

[0077] In this example, when the bandwidth filter power divider includes the first isolation resistor 61 and the second isolation resistor 62, and the resistance value of the first isolation resistor 61 is the first target resistance value, and the resistance value of the second isolation resistor 62 is the second target resistance value, the isolation of the output port of the bandwidth filter power divider is maximum, wherein the first target resistance value and the second target resistance value are determined based on the isolation bandwidth.

[0078] Specifically, the first target resistance value and the second target resistance value are determined based on a preset expression and an isolation bandwidth;

[0079] Among them, the preset expression is used to represent the mapping relationship between the resistance value of the first isolation resistor, the resistance value of the second isolation resistor and the bandwidth value of the isolation bandwidth. The preset expression is obtained based on the difference between the even-mode equivalent circuit of the main branch and the odd-mode equivalent circuit of the main branch, and the difference between the even-mode equivalent circuit of the reference branch and the odd-mode equivalent circuit of the reference branch. The analysis and derivation process of the preset expression can be found in the subsequent description.

[0080] In one embodiment, the electrical length of any transmission line in the bandwidth filter power divider is 90 degrees at the center frequency of the bandwidth filter power divider to ensure that the phase difference adjustment function of the main black box 14 and the reference black box 24 can be fully utilized.

[0081] Among them, the transmission line is a transmission line connecting two devices in the bandwidth filtering power divider. It should be understood that the main transmission line, the main step impedance open line, the main symmetrical open-circuited coupled line, the main black box, the reference transmission line, the reference step impedance open line, the reference symmetrical open-circuited coupled line and the reference black box all have transmission lines.

[0082] In one embodiment, the wavelength of the main step impedance open line is half the wavelength at the center frequency of the bandwidth filter power divider, and the wavelength of the reference step impedance open line is half the wavelength at the center frequency of the bandwidth filter power divider.

[0083] In this embodiment, the wavelengths of the main step impedance open circuit and the reference step impedance open circuit are set to be half of the wavelength at the center frequency of the bandwidth filter power divider, so as to fully stabilize the impedance at each position of the bandwidth filter power divider and reduce the probability of impedance offset at each position.

[0084] In one embodiment, the filtering function of the bandwidth filtering power divider is a generalized Chebyshev function, and the response of the filtering function of the bandwidth filtering power divider is determined based on a main out-of-band transmission zero point and a reference out-of-band transmission zero point, wherein the main out-of-band transmission zero point is the out-of-band transmission zero point corresponding to the main step impedance open line 12, and the reference out-of-band transmission zero point is the out-of-band transmission zero point corresponding to the reference step impedance open line 22.

[0085] Among them, the introduction of the main out-of-band transmission zero point and the reference out-of-band transmission zero point can be used to improve the frequency selectivity of the bandwidth filter power divider.

[0086] In one embodiment, the phase slope of the main branch is the same as the phase slope of the reference branch.

[0087] In this embodiment, by limiting the phase slope of the main branch to be the same as the phase slope of the reference branch, it is possible to ensure that a constant phase shift is achieved between the signal of the first output port 40 and the signal of the second output port 50 .

[0088] Without loss of generality, the equivalent circuit diagram of the bandwidth power splitter described in the present application can be as follows: Figure 2 As shown, it includes a main branch (Main branch, which can be understood as the aforementioned main branch) and a reference branch (Reference branch, which can be understood as the aforementioned reference branch).

[0089] The main branch consists of a transmission line segment (Z tm , which can be understood as the aforementioned main transmission line 11), a step impedance open line (Z s1m , Z s2m , which can be understood as the aforementioned main step impedance open line 12), a symmetrical open coupled line (Z e1m, Z o1m , a main symmetrical open-circuit coupling circuit 13) and a black box (which can be understood as the aforementioned main black box 14);

[0090] The reference branch also consists of a transmission line segment (Z tr , which can be understood as the aforementioned reference transmission line 21), a step impedance open line (Z s1r , Z s2r , which can be understood as the aforementioned reference step impedance open line 22), a symmetrical open coupled line (Z e1r , Z o1r , which can be understood as the aforementioned reference symmetrical open-circuit coupled line 23) and a black box (which can be understood as the aforementioned reference black box 24).

[0091] The black box includes a coupled line segment (Z in the main branch) e2m , Z o2m ), which can be understood as the aforementioned main coupling line, and the reference branch is (Z e2r , Z o2r ), which can be understood as the aforementioned reference coupled line), and is terminated with an open circuit (Type I) or short circuit (Type II) stub, and the electrical length of all transmission lines is unified to θ, where θ is 90° at the center frequency.

[0092] Among them, Port1 represents the aforementioned input port, Z s represents the impedance of the input port, Port2 represents the aforementioned second output port, and Z Lr represents the impedance of the second output port, Port3 represents the first output port, and Z Lm represents the impedance of the first output port.

[0093] It should be noted that Figure 2 In the embodiment, an open circuit (type I) or short circuit (type II) stub can be set in the black box in the main branch. Similarly, an open circuit (type I) or short circuit (type II) stub can be set in the black box in the reference branch.

[0094] In the above circuit structure, the half-wavelength step impedance open branch line not only introduces a pair of out-of-band transmission zeros (which can be understood as the aforementioned main out-of-band transmission zero and reference out-of-band transmission zero) to improve frequency selectivity, but also connects them together through a pair of isolation resistors to build an isolation network. Isolation resistor (R 1 , R 2 ) is naturally placed between the transmission line segment and the open stub, where the isolation resistor R 1 It can be understood that the aforementioned second isolation resistor 62, the isolation resistor R 2 It can be understood as the aforementioned first isolation resistor 61.

[0095] At the same time, an impedance of Z is introduced into the main branch.0 , the electrical length is θ d The phase delay line 70 is provided to achieve the desired phase difference.

[0096] Figure 3 for Figure 2 The equivalent circuit of the filter branch shown, that is, the equivalent circuit of the main branch / reference branch, Figure 3 The equivalent circuit shown also includes a transmission line segment (Z t ), a step impedance open line (Z s1 , Z s2 ), a symmetrical open-circuited coupled line (Z e1 , Z o1 ) and a black box (A L , B L , C L , D L ), Figure 3 The m subscript referring to the main branch and the r subscript referring to the reference branch are hidden in the relevant symbols.

[0097] When ideal impedance matching is achieved, no current flows through the isolation resistor, and the phase delay line has little effect on the impedance transformation of the input and output ports. They can be ignored in the analysis process. Based on this, Figure 3 As the equivalent circuit of the main branch, the setting of the phase delay line 70 is omitted, and, Figure 3 The overall transfer matrix of the filter branch in can be derived by multiplying the sub-matrices of the cascaded part, that is,

[0098]

[0099]

[0100] In the above formula, Y s1 is the input admittance of the main step impedance open line 12 / reference step impedance open line 22, A 1 ,B 1 ,C 1 ,D 1 represents the transfer matrix of the open coupled line, and A L ,B L ,C L ,D L Represents the transfer matrix of the black box.

[0101] Select the generalized Chebyshev function as the filtering function of the bandwidth filtering power divider described in the present application, then the filtering function S of the bandwidth filtering power divider is 11 and S 21 The response can be derived from its scattering matrix:

[0102]

[0103]

[0104] Among them, S11 response is used to represent Figure 3 The return loss curve of the input port in the equivalent circuit shown is used to represent the S21 response. Figure 3 Transfer characteristic curve of the equivalent circuit shown.

[0105] In the above formula, Z S and Z L They represent the source impedance (i.e., the impedance of the input port) and the load impedance (the impedance of the second output port corresponding to the main branch / the impedance of the first output port corresponding to the reference branch). In order to simplify the calculation expression, Z is defined here S / Z L =m, m≥1, Z L Normalized to 1Ω. After complex arithmetic operations and simplification, S in formula (3b) 21 can be simplified to:

[0106]

[0107] In the above formula, t = tanθ, X 1 ,X 2 and Y 1 -Y 6 It's about Z t ,Z e1 ,Z o1 ,Z e2 ,Z o2 ,Z s1 ,Z s2 and Z g The specific expressions of polynomial functions are shown in Table 1 and Table 2:

[0108] Table 1

[0109]

[0110] Table 2

[0111]

[0112] Due to the introduction of the main step impedance open line 12 and the reference step impedance open line 22, a pair of out-of-band transmission zeros are introduced within the frequency band. 21 = 0 to derive the position of the transmission zero in the frequency domain (f 0 indicates the fundamental frequency), which can be expressed as:

[0113]

[0114] Then, through the mapping function, the t domain can be converted to the ω domain according to the bandwidth FBW

[0115]

[0116] Therefore, the location of the zero point in the ω domain can be inferred to be

[0117] ω={-inf,-Z k ,Z k ,inf}(7a)

[0118]

[0119] For the S11 and S21 responses of the generalized Chebyshev function, they can be expressed in terms of zero-point distribution as

[0120]

[0121]

[0122] Where RL represents the return loss, P(ω), F(ω) and E(ω) are based on S 11 and S 21 The normalized polynomial function of the zero position in the curve, P(ω), can be derived from equation (7a):

[0123]

[0124] Then, because S 21 The imaginary part of the expression of all zeros of is equal to 0, which should satisfy the following equation, that is

[0125]

[0126] where k t C N (ω)=F(ω) / P(ω), k t is a constant, C N (ω) is a function of an N-order filter, whose poles and zeros are the roots of P(ω) = 0 and F(ω) = 0, respectively. For the generalized Chebyshev function, C N (ω) can be expressed as

[0127]

[0128]

[0129] In the above formula, ω n YesS 21 Expression of the nth transmission zero in the complex frequency domain.

[0130] It can be observed that the denominator polynomial in (11a) has the same root as P(ω), and the numerator polynomial has the same root as F(ω). N The coefficients of the numerator polynomial of (ω) can be solved and normalized by recursive method. In the present application example, the filter order N=5 is taken, so F(ω) can be expressed as

[0131]

[0132] Next we need to continue to construct E(ω). Consider the ideal case Can get

[0133] F(s)F(s) * +P(s)P(s) * / ε 2 =E(s)E(s) * ; s=jω (13)

[0134] The roots of the Hurwitz polynomial E(s) in equation (13) can be calculated by the alternating pole method, so E(s) can be expressed as

[0135] E(s)=s 5 +h 1 s 4 +h 2 s 3 +h 3 s 2 +h 4 s+h 5 (14)

[0136] in

[0137]

[0138]

[0139] δ 1 -δ 5 It's about Z k The function is specifically expressed as

[0140]

[0141] Finally, the function of S21 can be derived as

[0142]

[0143] Where η = tan(πFBW / 4), n 1 =1, h 1 -h 5 The specific expression is listed in formula (15a). Figure 3 When the circuit parameters in make equation (4) equal to the function in equation (17), a quasi-Chebyshev filtering response with a pair of out-of-band transmission zeros and a specified bandwidth and return loss level can be achieved.

[0144] Referring to the description of the above example, the generalized Chebyshev function is used as the filter function of the bandwidth filter power divider described in the present application, and the S of the filter function of the bandwidth filter power divider can be directly derived based on the position of the transmission zero point. 21 Response and S 11 The calculation complexity of the response function curve is relatively low compared with conventional derivation methods (such as characteristic function method and M matrix method);

[0145] It can also support the independent design of the main branch and the reference branch, thus achieving k 2 Specifically, we can first conduct a comprehensive design of a single filter branch, assuming that the power distribution ratio of the two output ports is k 2 :1, then according to the parallel connection principle of the two branches of the power divider, the impedance of the input port can be divided into (1+k 2 ) and 1 / (1+k 2 ),(normalized impedance z 0 ), therefore, when designing the circuit, we only need to determine the circuit type of the black box and then set the source impedance Z s Set to (1+k 2 ) and 1 / (1+k 2 ), load impedance Z L If it is set to 1, all circuit parameters of the reference branch and the main branch can be obtained separately, because the circuit parameters of the two branches are only related to themselves, that is, when designing the reference branch, the circuit parameters on the main path are not included, so it can support independent design of the two branches.

[0146] In applications, the circuit type of the main branch black box and the length of the phase delay line can be adaptively selected to flexibly achieve the signal phase difference between the first output port and the second output port in the range of 0° to 360°. Especially for the case where the signal phase difference is between 180° and 360°, the required phase delay line is shorter than the phase difference setting method provided by the related technology.

[0147] Specifically, when the black box of the main branch uses a type I short line, the signal phase difference ranges from 0° to 180°; and when the black box of the main branch uses a type II short line, the signal phase difference ranges from 180° to 360°.

[0148] In order to fully illustrate the performance advantages of the bandwidth filter power divider described in this application under various power distribution ratios, the example simulation is as follows:

[0149] like Figure 4 As shown, Figure 4 The theoretical and circuit simulation frequency responses of the black box for a type I stub setup are shown when the center bandwidth (FBW) of the bandwidth filter power divider is 75%, but the return loss level is different (Example I: RL = 20dB, Example II: RL = 25dB). Figure 4 It can be observed that the ideal fifth-order quasi-Chebyshev filter function with a pair of out-of-band transmission zeros agrees well with the circuit model of the broadband filter power divider.

[0150] Figure 4 In the example, the normalized impedances of Case I are:

[0151] Z t =1.4040,Z s1 =2.0214,Z s2 =2.1490,Z e1 =3.6060,Z o1 =1.3696,Z e2 =2.5200,

[0152] Z o2 =0.4714,Z g =1.2504, unit: ohm (Ω).

[0153] The normalized impedances for Case II are:

[0154] Z t =1.5880,Z s1 =3.0260,Z s2 =3.2166,Z e1 =4.4520,Z o1 =1.7364,Z e2 =2.5160,

[0155] Z o2 =0.4850,Z g =0.5512, unit: ohm (Ω).

[0156] See also Figure 5 , Figure 5 Further demonstrating that Figure 2 When the circuit type of the black box in is selected as type I and type II respectively, the amplitude response under the same return loss level (RL = 20dB) and different bandwidth conditions is shown in Table 3. Figure 5 Circuit parameters corresponding to each case in .

[0157] Table 3

[0158]

[0159] It can be noticed that no matter which type of circuit is selected in the black box, the in-band performance is the same in both cases, while the out-of-band suppression of type I is significantly better than that of type II. Therefore, in the design of filtering power dividers, type I circuits can be given priority.

[0160] In order to further illustrate the feasibility and performance of the bandwidth filter power divider in the case of unequal power distribution, this example designs and simulates several examples with different bandwidths and power distribution ratios. At this time, the circuit in the black box selects type I.

[0161] Assume that the power allocation ratio is k 2 (k 2 =Pport2 / Pport3,k 2 ≥1), theoretically, k 2 can be any value, however, as k 2 As the impedance of the transmission line portion of the branch with lower power increases, the impedance will increase. Considering the actual processing technology limitations, the maximum impedance can be limited to less than 150Ω.

[0162] It should be understood that in applications, high-impedance transmission lines are adaptively replaced to improve the maximum achievable power distribution ratio, such as using inductor-loaded transmission lines or equivalent T-junctions to replace high-impedance transmission lines.

[0163] Figure 6(a) shows the 2 =3, the comprehensive simulation results of unequal power filter power dividers with passband widths of 60%, 75% and 85% respectively, and the corresponding circuit normalized impedance parameters are shown in Table 4.

[0164] Table 4

[0165]

[0166] Figure 6(b) shows that under the same bandwidth (FBW = 75%), the power allocation ratio k 2 The theoretical results of design examples 2, 3, and 4 are shown in Table 5.

[0167] Table 5

[0168]

[0169]

[0170] It can be observed from FIG6 that a constant predetermined power division ratio is achieved within the entire operating bandwidth, so the case of unequal power division can also be comprehensively designed using the proposed theory.

[0171] Compared with the unequal power division filter power divider provided by the related technology, the new topology design of the bandwidth filter power divider proposed in this application can not only provide a broadband working bandwidth and a constant in-band power distribution ratio, but also does not require an additional transformer at the output port, and the structure is simpler.

[0172] In addition, the analysis and derivation process of the aforementioned preset expression is described as follows:

[0173] See also Figure 7 , Figure 7 The output port isolation (S 32 ) response, such as Figure 7 As shown, when the appropriate isolation resistor value is selected, S 32 The curve will produce a pair of transmission zeros ( Figure 7 f z3 and f z4 ), thereby effectively extending the isolation bandwidth.

[0174] Among them, the detailed expressions of isolation resistance under different bandwidth conditions are derived as follows:

[0175] The coupling lines and black boxes in each branch have little effect on isolation, that is, the isolation resistance R 1 and R 2 The value of admittance Y 1r(m) ,Y s1r(m) and Y s2r(m) Therefore, it can be omitted in the isolation analysis process Figure 2 The coupled lines and black boxes in the circuit are removed to simplify the topology. The simplified circuit diagram is shown in Figure 8(a). Since the power of the two output ports is not equal, the circuit structure must be asymmetric. Therefore, when performing odd-even mode analysis on the asymmetric structure, it is necessary to convert it into two symmetrical circuits consisting of a reference branch and a main branch. Figures 8(b) and 8(c) show the equivalent even-mode and odd-mode circuits of the reference branch and the main branch, respectively.

[0176] Assume that the power allocation ratio is k 2 , the normalized source admittance of the equivalent even mode of the reference branch can be expressed as k 2 / (1+k 2 )Ω -1 , the source admittance of the main branch is 1 / (1+k 2 )Ω -1 The values ​​of R1 and R2 in Figure 8(a) can be expressed as the isolation resistance R between the reference branch and the main branch. 1(2)r and R 1(2)m sum.

[0177] The even-mode and odd-mode input admittances in Figure 8(b) can be expressed as:

[0178]

[0179]

[0180] Among them, Y tr =1 / Z tr ,Y s1r =1 / Z s1r ,Y s2r =1 / Z s2r Then, Y er and Y or The real and imaginary parts G e(o)r and B e(o)r The following formula can be derived:

[0181]

[0182]

[0183]

[0184]

[0185] As shown in Figure 8, let equation (19) be z3 (θ3) satisfies G er =G or and B er =B or , isolation resistance R 1r and R 2r It can be expressed as:

[0186]

[0187]

[0188] Similarly, as shown in Figure 8(c), the even-mode and odd-mode input admittances of the main branch can be derived as:

[0189]

[0190]

[0191] Y em and Y om The real and imaginary parts of can be expressed as:

[0192]

[0193]

[0194]

[0195]

[0196] Then, R 1m and R 2m The value of G can also be obtained by setting G em =G om and B em =B om To deduce, that is:

[0197]

[0198]

[0199] Finally, the isolation resistor R 1 and R 2 It can be expressed as

[0200] R 1 =R 1r +R 1m ; R 2 =R 2r +R 2m (twenty four)

[0201] By selecting the position of θ3, S can be effectively controlled 32 The ripple level and bandwidth. Fig. 9 The isolation bandwidth of the filter power divider is shown as a function of the normalized frequency f. z3 / f 0 As can be seen from the figure, the bandwidth of the isolation will increase with f z3 decreases with the increase of . Fig.10 The output port isolation (S) of the three design examples with different transmission zero positions is further plotted. 32 ) simulation curve, when normalized f z3 When 0.64 is selected, the maximum bandwidth is 77.75%, and |S 32 |The ripple is 25dB.

[0202] It should be noted that Fig.10 The impedance of the isolation resistors in Example I are: R 1 =155Ω,R 2 =25Ω;

[0203] Fig.10 The impedance of the isolation resistor in Example II is: R 1 =205Ω,R 2 =200Ω;

[0204] Fig.10 The impedance of the isolation resistors in Example III is: R 1=210Ω,R 2 =300Ω.

[0205] The analysis of the phase characteristics of the bandwidth filter power divider described in the present application is as follows, wherein: Figure 2 The corresponding insertion phase of the reference branch and the main branch can be expressed as:

[0206]

[0207]

[0208] Where t = tan(πf / 2f 0 ),Y 1r -Y 6r and Y 1m -Y 6m are the polynomial functions corresponding to the transfer functions of the reference path and the main path, respectively.

[0209] The phase slope of the main branch is limited to be equal to the phase slope of the reference command to achieve a constant phase shift between the two output ports, that is:

[0210]

[0211] Note that the coupling line (Z e2 ,Z o2 ) has a coupling coefficient greater than 0.7 (as shown in Table 1-4), so the terminated open or short-circuited branches have little effect on their amplitude response, but can be used as a key parameter to control the phase slope.

[0212] When the circuit type of the black box of the main path is the same as that of the reference branch, equation (26) can be simplified as:

[0213]

[0214] Then, by letting RL m =RL r , FBW r =FBW m And solving equation (27), we can get the phase difference between the two output ports as:

[0215] ΔΦ=Φ r -Φ m =θ d (28)

[0216] Figure 11 depicts the Z at different specified passband bandwidths when the termination loading branch is open (Type I) or shorted (Type II). gm Comprehensive design curve of impedance value and phase shift value ΔΦ.

[0217] When ΔΦ=0°, Z can also be obtained gr As shown in Figure 11(a), when the loading branch is type I (open circuit), a wide range of phase shift from 0° to 180° can be obtained with bandwidths of 50%, 60%, and 75%, respectively.

[0218] When ΔΦ>180°, Z gm The impedance value of Z will be less than 20Ω. However, when the branch is short-circuited (Type II), Z gm As ΔΦ increases, it increases. From the curve in Figure 11(a), it can be seen that when Z gm Achievable (Z gm <150Ω), under the conditions of FBW=50%, 60% and 75%, the maximum achievable phase shift ΔΦ is 180°, 150° and 135° respectively.

[0219] When the terminal load of the main branch is different from the terminal load of the reference path, for example, if the reference branch is type I and the main path is type II, equation (26) can be simplified to:

[0220]

[0221] At this time, the phase difference between the two output ports can be derived as:

[0222] ΔΦ=Φ r -Φ m =π+θ d (30)

[0223] Similarly, when the reference path is type II and the main branch is type I, the phase shift ΔΦ between the two output ports will be

[0224] ΔΦ=Φ r -Φ m =π-θ d (31)

[0225] From formula (30), we can see that when 0°<θ d <180°, if the black box of the reference branch selects type I and the main path selects type II, the value range of ΔΦ will be 180°~360°; when the reference path is type II and the main path is type I, it can be seen from formula (31) that the phase shift ΔΦ is still between 0° and 180°.

[0226] We can only consider the case where the black box of the reference branch is type I and the main branch is type II to achieve a wider phase shift range. Figure 11(b) shows the Z under different bandwidth conditions in this case. gm It can be observed from the figure that the phase shift range of 180° to 360° can be easily achieved. gmThe impedance is still within the achievable range (0Ω <Z gm <150Ω).

[0227] Figures 12(a) and 12(b) further show that 2 =1 and FBW=75% under the conditions of simulated phase difference and amplitude response of the filter power divider with different phase shifts ΔΦ.

[0228] As shown in Figure 12(a), when 0°<ΔΦ<180°, the circuit type of the black box in the reference branch and the main branch is type I, and a constant phase difference is observed between the two output ports within the entire working bandwidth. At the same time, the amplitude difference between the two paths is almost negligible; when the phase shift is greater than 180°, the circuit type of the black box in the main branch should be type II.

[0229] As shown in Figure 12(b), the proposed filter power divider achieves a good phase difference in the range of 180° to 360°. It is worth noting that the transmission characteristic curves of the two output ports (|S 21 |,|S 31 |) has a slightly different response at both ends of the passband, which is mainly because the two branches contain different circuit structures. Therefore, when the circuit of the black box in the reference path selects type I, by selecting different types of circuit structures in the black box in the main path (type I: 0°~180°; type II: 180°~360°) and a 50Ω extension line of appropriate electrical length, a full range of phase shift of 0°~360° can be achieved.

[0230] It should be understood that the circuit design of the bandwidth filtering power divider described in the present application can support the use of a multi-layer stripline structure, and the top and bottom layers of the multi-layer stripline structure can be set as all-metal layers, so as to utilize the mutual cooperation of the all-metal top layer and the all-metal bottom layer to form a metal-like cavity, so that the bandwidth filtering power divider can have certain packaging characteristics and be isolated from external electromagnetic interference.

[0231] The terms "include", "comprising" or any other variants thereof in the embodiments of the present application are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0232] The term "or" in this application means an inclusive "or" rather than an exclusive "or". The mention of a "first" component does not necessarily require the provision of a "second" component. In addition, unless explicitly indicated, the "first" or "second" component does not limit the mentioned components to a specific order. The term "based on" means "based at least in part on".

[0233] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A bandwidth filtering power divider, characterized in that: The bandwidth filtering power divider comprises: a main branch, a reference branch, an input port, a first output port and a second output port; The main branch includes a main transmission line, a main step impedance open circuit, a main symmetrical open coupling circuit and a main black box; The reference branch includes a reference transmission line, a reference step impedance open line, a reference symmetrical open coupling line and a reference black box; The input port is electrically connected to the input end of the main transmission line, the output end of the main transmission line is electrically connected to the input end of the main step impedance open circuit, the output end of the main transmission line is electrically connected to the input end of the main symmetrical open-circuit coupling circuit, the output end of the main symmetrical open-circuit coupling circuit is electrically connected to the input end of the main black box, and the output end of the main black box is electrically connected to the first output port; The input port is electrically connected to the input end of the reference transmission line, the output end of the reference transmission line is electrically connected to the input end of the reference step impedance open line, the output end of the reference transmission line is electrically connected to the input end of the reference symmetrical open coupled line, the output end of the reference symmetrical open coupled line is electrically connected to the input end of the reference black box, and the output end of the reference black box is electrically connected to the second output port; The main black box and the reference black box are used to control the phase difference between the signal of the first output port and the signal of the second output port, and the adjustment range of the phase difference is 0° to 360°.

2. The bandwidth filtering power divider according to claim 1, characterized in that: The main black box comprises a main coupling line and a main short stub, and the main coupling line and the main short stub are electrically connected; The reference black box includes a reference coupling line and a reference stub, and the reference coupling line and the reference stub are electrically connected.

3. The bandwidth filtering power divider according to claim 2, characterized in that: The main stub is a short-circuited stub and the reference stub is an open-circuited stub; or, The main stub is an open stub and the reference stub is an open stub.

4. The bandwidth filtering power divider according to claim 1, characterized in that: The bandwidth filter power divider also includes a phase delay line; The output end of the main symmetrical open-circuit coupling circuit is electrically connected to the input end of the main black box, the output end of the main black box is electrically connected to the input end of the phase delay line, and the output end of the phase delay line is electrically connected to the first output port.

5. The bandwidth filtering power divider according to claim 1, characterized in that: The bandwidth filtering power divider further includes the first isolation resistor, a first end of the first isolation resistor is electrically connected to the main step impedance open circuit, and a second end of the first isolation resistor is electrically connected to the reference step impedance open circuit; and / or, The bandwidth filtering power divider also includes the second isolation resistor, a first end of the second isolation resistor is electrically connected to the output end of the main transmission line, and a second end of the second isolation resistor is electrically connected to the output end of the reference transmission line.

6. The bandwidth filtering power divider according to claim 5, characterized in that: When the bandwidth filtering power divider includes the first isolation resistor and the second isolation resistor, and the resistance value of the first isolation resistor is the first target resistance value, and the resistance value of the second isolation resistor is the second target resistance value, the isolation of the output port of the bandwidth filtering power divider is maximum, wherein the first target resistance value and the second target resistance value are determined based on the isolation bandwidth.

7. The bandwidth filtering power divider according to claim 6, characterized in that: The first target resistance value and the second target resistance value are determined based on a preset expression and an isolation bandwidth; Among them, the preset expression is used to represent the mapping relationship between the resistance value of the first isolation resistor, the resistance value of the second isolation resistor and the bandwidth value of the isolation bandwidth, and the preset expression is obtained based on the difference between the even-mode equivalent circuit of the main branch and the odd-mode equivalent circuit of the main branch, and the difference between the even-mode equivalent circuit of the reference branch and the odd-mode equivalent circuit of the reference branch.

8. The bandwidth filtering power divider according to any one of claims 1 to 7, characterized in that: The electrical length of any one transmission line in the bandwidth filter power divider is 90 degrees at the center frequency of the bandwidth filter power divider, wherein the transmission line is a transmission line connecting two devices in the bandwidth filter power divider; and / or, The wavelength of the main step impedance open line is half of the wavelength at the center frequency of the bandwidth filter power divider, and the wavelength of the reference step impedance open line is half of the wavelength at the center frequency of the bandwidth filter power divider.

9. The bandwidth filtering power divider according to any one of claims 1 to 7, characterized in that: The filtering function of the bandwidth filtering power divider is a generalized Chebyshev function, and the response of the filtering function of the bandwidth filtering power divider is determined based on a main out-of-band transmission zero point and a reference out-of-band transmission zero point, wherein the main out-of-band transmission zero point is the out-of-band transmission zero point corresponding to the main step impedance open circuit, and the reference out-of-band transmission zero point is the out-of-band transmission zero point corresponding to the reference step impedance open circuit.

10. The bandwidth filtering power divider according to any one of claims 1 to 7, characterized in that: The phase slope of the main branch is the same as the phase slope of the reference branch.

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