A 10-fold frequency 3dB bridge

Abstract

The present invention discloses a 10-fold frequency 3dB bridge including a point frequency bridge and a reverse transformer group, wherein the point frequency bridge includes a high frequency bridge, an intermediate frequency bridge and a low frequency bridge, and the reverse transformer group includes a co-directional transmission line transformer and a reverse transmission line transformer; the high frequency bridge includes a first transformer, a first polarity capacitor and a second polarity capacitor, the low frequency bridge includes a second transformer, a third transformer and a third polarity capacitor, and the intermediate frequency bridge includes a sixth transformer, a fourth polarity capacitor and a fifth polarity capacitor; the input end signal passes through the high frequency bridge and the low frequency bridge in sequence, and then passes through the parallel co-directional transformer and the reverse transformer respectively, and then passes through the intermediate frequency bridge and then outputs. The bridge is mainly used in power distribution and synthesis, and is more used in power amplifiers. Its advantage is that the common end standing wave ratio does not change with the impedance change of the two input or output ends, has a stable standing wave ratio, and has the port matching of the power amplifier.

Description

Technical Field

[0001] The invention relates to the field of circuits, and in particular to a 10-fold frequency-band 3dB bridge. Background Art

[0002] 3db bridge is also called frequency combiner, which can continuously sample the transmission power along a certain direction of the transmission line, and can divide an input signal into two signals with equal amplitude and 90° phase difference. It is mainly used for multi-signal combination to improve the utilization rate of output signals, and is widely used in indoor coverage systems to combine base station signals, and the application effect is very good in such places.

[0003] However, in the prior art, common problems involve:

[0004] 1) The output signal is unstable;

[0005] 2) The amplitude imbalance is high;

[0006] 3) Phase imbalance is prominent. Summary of the invention

[0007] In order to solve the above problems, the present invention proposes a 10-fold frequency-band 3dB bridge.

[0008] A 10-fold frequency 3dB bridge comprises a point frequency bridge and a reverse transformer group, wherein the point frequency bridge comprises a high frequency bridge, an intermediate frequency bridge and a low frequency bridge, and the reverse transformer group comprises a same-direction transmission line transformer and a reverse transmission line transformer; the high frequency bridge comprises a first transformer, a first polarity capacitor and a second polarity capacitor, the low frequency bridge comprises a second transformer, a third transformer and a third polarity capacitor, and the intermediate frequency bridge comprises a sixth transformer, a fourth polarity capacitor and a fifth polarity capacitor;

[0009] One end of the primary coil of the first transformer is connected to one end of the secondary coil of the third transformer, one end of the primary coil of the third transformer is connected to one end of the primary coil of the reverse transmission line transformer, and one end of the secondary coil of the reverse transmission line transformer is connected to one end of the secondary coil of the sixth transformer;

[0010] One end of the secondary coil of the first transformer is connected to one end of the primary coil of the second transformer, one end of the secondary coil of the second transformer is connected to one end of the primary coil of the same-direction transmission line transformer, and the other end of the primary coil of the same-direction transmission line transformer is connected to one end of the primary coil of the sixth transformer;

[0011] The other end of the primary coil of the second transformer is connected to the other end of the primary coil of the third transformer, and the other end of the secondary coil of the second transformer is connected to the other end of the secondary coil of the third transformer;

[0012] Both ends of the secondary coil of the same-direction transmission line transformer are grounded, and the other end of the primary coil and the other end of the secondary coil of the reverse transmission line transformer are grounded.

[0013] The anode of the first polarity capacitor is connected to one end of the secondary coil of the first transformer, and the cathode is connected to the other end of the primary coil of the first transformer;

[0014] The anode of the second polarity capacitor is connected to the other end of the secondary coil of the first transformer, and the cathode is connected to one end of the primary coil of the first transformer;

[0015] The anode of the third polarity capacitor is connected to the other end of the secondary coil of the second transformer, and the cathode is connected to the other end of the primary coil of the second transformer;

[0016] The anode of the fourth polarity capacitor is connected to one end of the primary coil of the sixth transformer, and the cathode is connected to the other end of the secondary coil of the sixth transformer;

[0017] The anode of the fifth polarity capacitor is connected to the other end of the primary coil of the sixth transformer, and the cathode is connected to one end of the secondary coil of the sixth transformer.

[0018] The 10-octave 3dB bridge also includes a first port impedance, a second port impedance, a third port impedance and a fourth port impedance, wherein the positive poles of the first port impedance, the second port impedance, the third port impedance and the fourth port impedance are respectively connected to the other end of the primary coil of the first transformer, the other end of the secondary coil of the first transformer, the other end of the secondary coil of the sixth transformer and the other end of the primary coil of the sixth transformer; the negative poles of the first port impedance, the second port impedance, the third port impedance and the fourth port impedance are all grounded; one end of the first port impedance is a first input end, one end of the second port impedance is a second input end, one end of the third port impedance is a first output end, and one end of the fourth port impedance is a second output end.

[0019] The first transformer, the second transformer, the third transformer, the sixth transformer, the same-direction transmission line transformer and the reverse transmission line transformer are all 1:1 transmission line transformers.

[0020] The primary voltage v1 and the secondary voltage v2 of the first transformer are obtained by the primary current i1 and the secondary current i2 according to the following formula:

[0021] Formula (1): v1=L1*di1 / dt+M*di2 / dt=j*ω*L1*i1+j*ω*M*i2;

[0022] Formula (2): v2=L2*di2 / dt+M*di1 / dt=j*ω*L1*i2+j*ω*M*i1;

[0023] Where, M is the mutual inductance, 1:1 transformer M=L1=L2=L, L1 is the inductance of the primary coil of the first transformer, L2 is the inductance of the secondary coil of the first transformer, L1 and L2 are determined by the input and output frequencies;

[0024] Then we get formula (3) v = j * ω * L * (i1 + i2);

[0025] Formula (1), formula (2) and formula (3) are all suitable for calculating the primary voltage and secondary voltage of the second transformer, the third transformer, the sixth transformer, the same-direction transmission line transformer and the reverse transmission line transformer.

[0026] The capacitance values ​​of the first polarity capacitor, the second polarity capacitor, the third polarity capacitor, the fourth polarity capacitor and the fifth polarity capacitor are all determined by the input frequency and the output frequency.

[0027] The high-frequency bridge adopts an even-odd mode analysis method, which includes an even mode analysis and an odd mode analysis;

[0028] The even-mode analysis: Due to the symmetry of the high-frequency bridge circuit, the voltage at the first input terminal is the same as the voltage at the second input terminal, and the current i is also equal in magnitude and direction, that is, i1=i2=i. At this time, the first capacitor and the second capacitor can be removed;

[0029] The odd-mode analysis: Due to the symmetry of the circuit, the voltage at the first input terminal and the voltage at the second input terminal are opposite in direction and equal in magnitude, and the current i is also equal in magnitude and opposite in direction, that is, i1=-i2=i, and the capacitance between the first input terminal and the second input terminal can be characterized by 2*c grounding;

[0030] The odd-even mode analysis method is also applicable to medium-frequency bridges and low-frequency bridges.

[0031] The inductance corresponding to the primary coil and the secondary coil of the first transformer is L1=L2=50 / (3π*F2) henry;

[0032] The inductance L1=L2=25 / (1.5π*F1) Henry corresponding to the primary coil and the secondary coil of the second transformer;

[0033] The inductance L1=L2=25 / (1.5π*F1) Henry corresponding to the primary coil and the secondary coil of the third transformer;

[0034] The inductance L1=L2>>50 / (2π*F1) Henry corresponding to the primary coil and the secondary coil of the first codirectional transmission line transformer;

[0035] The inductance L1=L2>>50 / (2π*F1) Henry corresponding to the primary coil and the secondary coil of the reverse transmission line transformer;

[0036] The inductance L1=L2=50 / (6π*F1) Henry corresponding to the primary coil and the secondary coil of the sixth transformer;

[0037] The first polarity capacitor C1=1 / (3π*F2*100);

[0038] The second polarity capacitor C2=1 / (3π*F2*100);

[0039] The third polarity capacitor C3=1 / (1.5π*F1*50) method;

[0040] The fourth polarity capacitor C4=1 / (6π*F1*100);

[0041] The fifth polarity capacitor C5=1 / (6π*F1*100);

[0042] The F2 / F1=10.

[0043] The beneficial effects of the present invention are: it can realize ten-fold frequency change, and at the same time, the output signal is stable. Within the ten-fold frequency range, the equal-amplitude orthogonal output is performed, the amplitude imbalance is less than 0.7dB, and the phase imbalance is less than 3°. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the present invention;

[0045] Figure 2 It is the even-mode analysis equivalent diagram of a high-frequency bridge;

[0046] Figure 3 It is the odd-mode analysis equivalent diagram of a high-frequency bridge;

[0047] Figure 4 is the frequency response curve. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0049] like Figure 1 As shown, it includes a point frequency bridge and a reverse transformer group, the point frequency bridge includes a high frequency bridge, an intermediate frequency bridge and a low frequency bridge, the reverse transformer group includes a same direction transmission line transformer and a reverse transmission line transformer; the high frequency bridge includes a first transformer, a first polarity capacitor and a second polarity capacitor, the low frequency bridge includes a second transformer, a third transformer and a third polarity capacitor, the intermediate frequency bridge includes a sixth transformer, a fourth polarity capacitor and a fifth polarity capacitor;

[0050] One end of the primary coil of the first transformer is connected to one end of the secondary coil of the third transformer, one end of the primary coil of the third transformer is connected to one end of the primary coil of the reverse transmission line transformer, and one end of the secondary coil of the reverse transmission line transformer is connected to one end of the secondary coil of the sixth transformer;

[0051] One end of the secondary coil of the first transformer is connected to one end of the primary coil of the second transformer, one end of the secondary coil of the second transformer is connected to one end of the primary coil of the same-direction transmission line transformer, and the other end of the primary coil of the same-direction transmission line transformer is connected to one end of the primary coil of the sixth transformer;

[0052] The other end of the primary coil of the second transformer is connected to the other end of the primary coil of the third transformer, and the other end of the secondary coil of the second transformer is connected to the other end of the secondary coil of the third transformer;

[0053] Both ends of the secondary coil of the same-direction transmission line transformer are grounded, and the other end of the primary coil and the other end of the secondary coil of the reverse transmission line transformer are grounded.

[0054] The anode of the first polarity capacitor is connected to one end of the secondary coil of the first transformer, and the cathode is connected to the other end of the primary coil of the first transformer;

[0055] The anode of the second polarity capacitor is connected to the other end of the secondary coil of the first transformer, and the cathode is connected to one end of the primary coil of the first transformer;

[0056] The anode of the third polarity capacitor is connected to the other end of the secondary coil of the second transformer, and the cathode is connected to the other end of the primary coil of the second transformer;

[0057] The anode of the fourth polarity capacitor is connected to one end of the primary coil of the sixth transformer, and the cathode is connected to the other end of the secondary coil of the sixth transformer;

[0058] The anode of the fifth polarity capacitor is connected to the other end of the primary coil of the sixth transformer, and the cathode is connected to one end of the secondary coil of the sixth transformer.

[0059] The capacitors are labeled as follows: first polarity capacitor C1, second polarity capacitor C2, third polarity capacitor C3, fourth polarity capacitor C4, and fifth polarity capacitor C5;

[0060] The 10-octave 3dB bridge also includes a first port impedance, a second port impedance, a third port impedance and a fourth port impedance, wherein the positive poles of the first port impedance, the second port impedance, the third port impedance and the fourth port impedance are respectively connected to the other end of the primary coil of the first transformer, the other end of the secondary coil of the first transformer, the other end of the secondary coil of the sixth transformer and the other end of the primary coil of the sixth transformer; the negative poles of the first port impedance, the second port impedance, the third port impedance and the fourth port impedance are all grounded.

[0061] One end of the first port impedance is a first input end, one end of the second port impedance is a second input end, one end of the third port impedance is a first output end, and one end of the fourth port impedance is a second output end.

[0062] The first transformer, the second transformer, the third transformer, the sixth transformer, the same-direction transmission line transformer and the reverse transmission line transformer are all 1:1 transmission line transformers.

[0063] The first port impedance, the second port impedance, the third port impedance and the fourth port impedance are all 50 ohms.

[0064] The inductance values ​​of the primary coils and the secondary coils of the first transformer, the second transformer, the third transformer, the sixth transformer, the same-direction transmission line transformer and the reverse transmission line transformer are all determined by the input frequency and the output frequency.

[0065] The capacitance values ​​of the first polarity capacitor, the second polarity capacitor, the third polarity capacitor, the fourth polarity capacitor and the fifth polarity capacitor are also determined by the input frequency and the output frequency.

[0066] That is: the inductance corresponding to the primary coil and the secondary coil of the first transformer is L1=L2=50 / (3π*F2) henry;

[0067] The inductance L1=L2=25 / (1.5π*F1) Henry corresponding to the primary coil and the secondary coil of the second transformer;

[0068] The inductance L1=L2=25 / (1.5π*F1) Henry corresponding to the primary coil and the secondary coil of the third transformer;

[0069] The inductance L1=L2>>50 / (2π*F1) Henry corresponding to the primary coil and the secondary coil of the first codirectional transmission line transformer;

[0070] The inductance L1=L2>>50 / (2π*F1) Henry corresponding to the primary coil and the secondary coil of the reverse transmission line transformer;

[0071] The inductance L1=L2=50 / (6π*F1) Henry corresponding to the primary coil and the secondary coil of the sixth transformer;

[0072] The first polarity capacitor C1=1 / (3π*F2*100);

[0073] The second polarity capacitor C2=1 / (3π*F2*100);

[0074] The third polarity capacitor C3=1 / (1.5π*F1*50) method;

[0075] The fourth polarity capacitor C4=1 / (6π*F1*100);

[0076] The fifth polarity capacitor C5=1 / (6π*F1*100);

[0077] The F2 / F1=10.

[0078] Transformer Analysis:

[0079] The primary voltage v1 and the secondary voltage v2 of the first transformer are obtained by the primary current i1 and the secondary current i2 according to the following formula:

[0080] Formula (1): v1=L1*di1 / dt+M*di2 / dt=j*ω*L1*i1+j*ω*M*i2;

[0081] Formula (2): v2=L2*di2 / dt+M*di1 / dt=j*ω*L1*i2+j*ω*M*i1;

[0082] Where, M is the mutual inductance, 1:1 transformer M=L1=L2=L, L1 is the inductance of the primary coil of the first transformer, L2 is the inductance of the secondary coil of the first transformer, L1 and L2 are determined by the input and output frequencies;

[0083] Then we get formula (3) v = j * ω * L * (i1 + i2);

[0084] The formula (1), formula (2) and formula (3) are all suitable for calculating the primary voltage and secondary voltage of the second transformer, the third transformer, the sixth transformer, the same-direction transmission line transformer and the reverse transmission line transformer. (3)

[0085] Bridge analysis, using odd-even mode analysis:

[0086] Even-mode analysis: Due to the symmetry of the circuit, the voltages at the first input terminal P1 and the second input terminal P2 are the same, and the currents i are also equal in magnitude and direction, i1=i2=i. The capacitor between the first input terminal P1 and the second input terminal P2 can be removed, leaving only the inductor. For example, Figure 2As shown, from formula (3), we can know:

[0087] v=j*ω*L*(i1+i2)=2*j*ω*L*i, that is, the inductive reactance is 2*j*ω*L.

[0088] Γe=(2*j*ω*L+50-50) / (2*j*ω*L+50+50)=2*j*ω*L / (2*j*ω*L+100) (port impedance 50 ohms);

[0089] Te=2*50 / (2*j*ω*L+100).

[0090] Odd-mode analysis: Due to the symmetry of the circuit, the voltages at the first input terminal P1 and the second input terminal P2 are opposite and equal in magnitude, and the current i is also equal in magnitude and opposite in direction, i1=-i2=i, and the capacitance between the first input terminal P1 and the second input terminal P2 can be characterized by 2*c grounding, such as Figure 3 As shown, from formula (3), we can get:

[0091] v=2*j*ω*L*(i1+i2)=0, that is, the inductive reactance is 0. There are only two capacitors connected in parallel to the ground between the first input terminals P1 and P3. The combined capacitance is 4*C. It is easy to get

[0092] Γo=(50 / (200*j*ω*c+1)-50) / (50 / (200*j*ω*c+1)+50)=-100*j*ω*c / (100*j*ω*c+1);

[0093] To=1 / (100*j*ω*c+1).

[0094] From the odd-even relationship, we can know that:

[0095] S11=0.5*Γe+0.5*Γo=j*ω*L / (2*j*ω*L+100)-50*j*ω*c / (100*j*ω*c+1)

[0096] S31=0.5*Te+0.5*To=50 / (2*j*ω*L+100)+0.5 / (100*j*ω*c+1)

[0097] S21=0.5*Γe-0.5*Γo=j*ω*L / (2*j*ω*L+100)+50*j*ω*c / (100*j*ω*c+1)

[0098] S41=0.5*Te-0.5*To=50 / (2*j*ω*L+100)-0.5 / (100*j*ω*c+1)

[0099] The inductance and capacitance values ​​of the high-frequency bridge composed of the first transformer MUC1 and C1, C2 and the medium-frequency bridge composed of the first transformer MUC6 and C4, C5 are known to be: L / C=5000 Substituting into the above formula, we can get

[0100] S11=0;

[0101] S31=1 / (100*j*ω*c+1);

[0102] S21=100*j*ω*c / (100*j*ω*c+1);

[0103] S41=0;

[0104] S21 / S31=j*100*ω*c, so ang(S21)-ang(S31)=90 degrees;

[0105] When 100*ω*c=1, S31=1 / (1+j)=0.707∠-45º, S21=j / (1+j)=0.707∠45º.

[0106] Similarly, the values ​​of the inductance and capacitance of the low-frequency bridge composed of the first transformer MUC2, the first transformer MUC3 and C3 are: L / C=1250, and have the following S parameters.

[0107] S11=0;

[0108] S31=1 / (50*j*ω*c+1);

[0109] S21=50*j*ω*c / (50*j*ω*c+1);

[0110] S41=0;

[0111] S21 / S31=j*100*ω*c, so ang(S21)-ang(S31)=90 degrees.

[0112] After the bridges are cascaded in sequence, Figure 1 As shown, the voltages at each point are (according to the previous S parameter formula):

[0113] VA=V1 / (100*j*ω*C1+1)

[0114] VB=V1*100*j*ω*C1 / (100*j*ω*C1+1)

[0115] VC=VA*50*j*ω*C2 / (50*j*ω*C2+1)+VB / (50*j*ω*C2+1)

[0116] $V_D = \frac{V_B \cdot 50 \cdot j \cdot \omega \cdot C_2}{50 \cdot j \cdot \omega \cdot C_2 + 1}+\frac{V_A}{50 \cdot j \cdot \omega \cdot C_2 + 1}$

[0117] $V_E = V_C$ (in the same direction), $V_F=-V_D$ (in the opposite direction)

[0118] $V_3=\frac{V_E \cdot 100 \cdot j \cdot \omega \cdot C_3}{100 \cdot j \cdot \omega \cdot C_3 + 1}+\frac{V_F}{100 \cdot j \cdot \omega \cdot C_3 + 1}$

[0119] $= \frac{V_C \cdot 100 \cdot j \cdot \omega \cdot C_3}{100 \cdot j \cdot \omega \cdot C_3 + 1}-\frac{V_D}{100 \cdot j \cdot \omega \cdot C_3 + 1}$

[0120] $=(\frac{V_A \cdot 50 \cdot j \cdot \omega \cdot C_2}{50 \cdot j \cdot \omega \cdot C_2 + 1}+\frac{V_B}{50 \cdot j \cdot \omega \cdot C_1 + 1})\cdot\frac{100 \cdot j \cdot \omega \cdot C_3}{100 \cdot j \cdot \omega \cdot C_3 + 1}$

[0121] $-(\frac{V_B \cdot 50 \cdot j \cdot \omega \cdot C_2}{50 \cdot j \cdot \omega \cdot C_2 + 1}+\frac{V_A}{50 \cdot j \cdot \omega \cdot C_2 + 1}) / (100 \cdot j \cdot \omega \cdot C_3 + 1)$

[0122] $=(\frac{V_1}{100 \cdot j \cdot \omega \cdot c + 1}\cdot\frac{50 \cdot j \cdot \omega \cdot C_2}{50 \cdot j \cdot \omega \cdot C_2 + 1}+\frac{V_1 \cdot 100 \cdot j \cdot \omega \cdot C_1}{100 \cdot j \cdot \omega \cdot C_1 + 1}$

[0123] $ / (50 \cdot j \cdot \omega \cdot C_2 + 1))\cdot\frac{100 \cdot j \cdot \omega \cdot C_3}{100 \cdot j \cdot \omega \cdot C_3 + 1}$

[0124] $-(\frac{V_1 \cdot 100 \cdot j \cdot \omega \cdot C_1}{100 \cdot j \cdot \omega \cdot C_1 + 1}\cdot\frac{50 \cdot j \cdot \omega \cdot C_2}{50 \cdot j \cdot \omega \cdot C_2 + 1}$

[0125] $+\frac{V_1}{100 \cdot j \cdot \omega \cdot C_1 + 1} / (50 \cdot j \cdot \omega \cdot C_2 + 1)) / (100 \cdot j \cdot \omega \cdot C_3 + 1)$

[0126] $V_4=\frac{V_F \cdot 100 \cdot j \cdot \omega \cdot C_3}{100 \cdot j \cdot \omega \cdot C_3 + 1}+\frac{V_E}{100 \cdot j \cdot \omega \cdot C_3 + 1}$

[0127] $=- \frac{V_D \cdot 100 \cdot j \cdot \omega \cdot C_3}{100 \cdot j \cdot \omega \cdot C_3 + 1}+\frac{V_C}{100 \cdot j \cdot \omega \cdot C_3 + 1}$

[0128] $=-(\frac{V_B \cdot 50 \cdot j \cdot \omega \cdot C_2}{50 \cdot j \cdot \omega \cdot C_2 + 1}+\frac{V_A}{50 \cdot j \cdot \omega \cdot C_2 + 1})\cdot\frac{100 \cdot j \cdot \omega \cdot C_3}{100 \cdot j \cdot \omega \cdot C_3 + 1}$

[0129] +(VA*50*j*ω*C2 / (50*j*ω*C2+1)+VB / (50*j*ω*C2+1)) / (100*j*ω*C3+1)

[0130] =-(V1*100*j*ω*C1 / (100*j*ω*C1+1)*50*j*ω*C2 / (50*j*ω*C2+1)

[0131] +V1 / (100*j*ω*C1+1) / (50*j*ω*C2+1))*100*j*ω*C3 / (100*j*ω*C3+1)

[0132] +(V1 / (100*j*ω*C1+1)*50*j*ω*C2 / (50*j*ω*C2+1)+V1*100*j*ω*C1 / (100*j*ω*C1+1)

[0133] / (50*j*ω*C2+1)) / (100*j*ω*C3+1)

[0134] If F1=3MHz, F2=30MHz, C1=C2=36pF, C2=1592pF, C3=C4=173pF, the following frequency response curve can be obtained from the expressions of V3 and V4: Figure 4 shown.

[0135] It should be noted that, for the above-mentioned various method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and units involved are not necessarily required by this application.

[0136] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0137] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a ROM, a RAM, etc.

[0138] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A 10-fold frequency 3dB bridge, characterized in that: It includes a point frequency bridge and a reverse transformer group, wherein the point frequency bridge includes a high frequency bridge, an intermediate frequency bridge and a low frequency bridge, and the reverse transformer group includes a same-direction transmission line transformer and a reverse transmission line transformer; the high frequency bridge includes a first transformer, a first polarity capacitor and a second polarity capacitor, the low frequency bridge includes a second transformer, a third transformer and a third polarity capacitor, and the intermediate frequency bridge includes a sixth transformer, a fourth polarity capacitor and a fifth polarity capacitor; One end of the primary coil of the first transformer is connected to one end of the secondary coil of the third transformer, one end of the primary coil of the third transformer is connected to one end of the primary coil of the reverse transmission line transformer, and one end of the secondary coil of the reverse transmission line transformer is connected to one end of the secondary coil of the sixth transformer; One end of the secondary coil of the first transformer is connected to one end of the primary coil of the second transformer, one end of the secondary coil of the second transformer is connected to one end of the primary coil of the same-direction transmission line transformer, and the other end of the primary coil of the same-direction transmission line transformer is connected to one end of the primary coil of the sixth transformer; The other end of the primary coil of the second transformer is connected to the other end of the primary coil of the third transformer, and the other end of the secondary coil of the second transformer is connected to the other end of the secondary coil of the third transformer; Both ends of the secondary coil of the same-direction transmission line transformer are grounded, and the other end of the primary coil and the other end of the secondary coil of the reverse transmission line transformer are grounded; The anode of the first polarity capacitor is connected to one end of the secondary coil of the first transformer, and the cathode is connected to the other end of the primary coil of the first transformer; The anode of the second polarity capacitor is connected to the other end of the secondary coil of the first transformer, and the cathode is connected to one end of the primary coil of the first transformer; The anode of the third polarity capacitor is connected to the other end of the secondary coil of the second transformer, and the cathode is connected to the other end of the primary coil of the second transformer; The anode of the fourth polarity capacitor is connected to one end of the primary coil of the sixth transformer, and the cathode is connected to the other end of the secondary coil of the sixth transformer; The anode of the fifth polarity capacitor is connected to the other end of the primary coil of the sixth transformer, and the cathode is connected to one end of the secondary coil of the sixth transformer; It also includes a first port impedance, a second port impedance, a third port impedance and a fourth port impedance, wherein the positive electrodes of the first port impedance, the second port impedance, the third port impedance and the fourth port impedance are respectively connected to the other end of the primary coil of the first transformer, the other end of the secondary coil of the first transformer, the other end of the secondary coil of the sixth transformer and the other end of the primary coil of the sixth transformer; the negative electrodes of the first port impedance, the second port impedance, the third port impedance and the fourth port impedance are all grounded; one end of the first port impedance is the first input end, one end of the second port impedance is the second input end, one end of the third port impedance is the first output end, and one end of the fourth port impedance is the second output end; The first transformer, the second transformer, the third transformer, the sixth transformer, the same-direction transmission line transformer and the reverse transmission line transformer are all 1:1 transmission line transformers.

2. A 10-fold frequency-band 3dB bridge as claimed in claim 1, characterized in that: The primary voltage v1 and the secondary voltage v2 of the first transformer are obtained by the primary current i1 and the secondary current i2 according to the following formula: Formula (1): v1=L1*di1 / dt+M*di2 / dt=j*ω*L1*i1+j*ω*M*i2; Formula (2): v2=L2*di2 / dt+M*di1 / dt=j*ω*L1*i2+j*ω*M*i1; Where, M is the mutual inductance, 1:1 transformer M=L1=L2=L, L1 is the inductance of the primary coil of the first transformer, L2 is the inductance of the secondary coil of the first transformer, L1 and L2 are determined by the input and output frequencies; Then we get formula (3) v = j * ω * L * (i1 + i2); Formula (1), formula (2) and formula (3) are all suitable for calculating the primary voltage and secondary voltage of the second transformer, the third transformer, the sixth transformer, the same-direction transmission line transformer and the reverse transmission line transformer.

3. A 10-fold frequency-band 3dB bridge as claimed in claim 1, characterized in that: The capacitance values ​​of the first polarity capacitor, the second polarity capacitor, the third polarity capacitor, the fourth polarity capacitor and the fifth polarity capacitor are all determined by the input frequency and the output frequency.

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