Miniaturized broadband balun based on IPD technology

Abstract

The invention relates to the technical field of broadband baluns, and discloses a miniaturized broadband balun based on an IPD process, which comprises a first transmission line, a second transmission line, a third transmission line, a fourth transmission line, a fifth transmission line and a sixth transmission line. According to the invention, the balun with a distributed structure is loaded by using the lumped capacitor, so that a transmission line shorter than a quarter of wavelength can act on the same frequency band, and miniaturization is realized; moreover, a series coupling line is introduced to adjust the balance degree of the phase and amplitude of the main body part of the balun in a passband range, so that the design has smaller phase unbalance degree and amplitude unbalance degree compared with a balun in the same frequency band.

Description

Technical Field

[0001] The present invention relates to the technical field of broadband baluns, and in particular to a miniaturized broadband balun based on an IPD process. Background Art

[0002] With the rapid advancement of communication technology and the continuous growth of communication capacity, modern communication systems are gradually developing towards miniaturization, multi-function and high integration. Therefore, the demand for miniaturized and broadband microwave RF devices in communication systems has become more urgent.

[0003] Baluns are mainly used for the conversion of high-frequency RF and microwave signals, helping to convert unbalanced signals into balanced signals. This is particularly important in antenna design, RF amplifiers and signal processing equipment to reduce signal interference and improve the overall performance of the system. Wireless communication systems often need to handle a wide range of frequencies. Wideband baluns are designed to support the conversion of wideband signals and ensure stable performance at various frequencies. In current technology, baluns have problems such as narrow frequency band, poor practicality, large size and poor performance, which cannot meet the needs of modern communication systems. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a miniaturized broadband balun based on the IPD process.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] A miniaturized broadband balun based on IPD process, comprising:

[0007] a first transmission line, a second transmission line, a third transmission line, a fourth transmission line, a fifth transmission line, and a sixth transmission line;

[0008] One end of the second transmission line is connected to the first input port, and the other end of the second transmission line is connected to one end of the fifth transmission line; the other end of the fifth transmission line is connected to one end of the sixth transmission line, and the fifth transmission line and the sixth transmission line are coupled to each other; the other end of the sixth transmission line is connected to one end of the fourth transmission line; the other end of the fourth transmission line is connected to the second ground terminal via a first series capacitor;

[0009] One end of the first transmission line is connected to the second input port, the other end of the first transmission line is connected to the first ground terminal, and the first transmission line and the second transmission line are coupled to each other; the second input port is connected to the third ground terminal via the first parallel capacitor;

[0010] One end of the third transmission line is connected to the third input port, the other end of the third transmission line is grounded, and the third transmission line is coupled to the fourth transmission line; the second input port is connected to the fourth ground terminal via a second parallel capacitor.

[0011] As a preference, it also includes:

[0012] a first microstrip line, a second microstrip line, and a third microstrip line;

[0013] One end of the first microstrip line is connected to one end of the second microstrip line, the connecting end of the first microstrip line and the second microstrip line is connected to a third ground end via a third microstrip line, and the first microstrip line and the second microstrip line are coupled to each other.

[0014] As a preference, it also includes:

[0015] a fourth microstrip line, a fifth microstrip line, and a sixth microstrip line;

[0016] One end of the fourth microstrip line is connected to one end of the fifth microstrip line, the connecting end of the fourth microstrip line and the fifth microstrip line is connected to the fourth ground end through the sixth microstrip line, and the fourth microstrip line and the fifth microstrip line are coupled to each other.

[0017] Preferably, the line widths of the first microstrip line and the second microstrip line are greater than those of the fourth microstrip line and the fifth microstrip line.

[0018] Preferably, the broadband balun is constructed using an IPD process.

[0019] Preferably, the substrate material of the broadband balun is gallium arsenide.

[0020] Preferably, the first series capacitor is a MIM flat plate capacitor.

[0021] Preferably, the first parallel capacitor is a MIM flat plate capacitor.

[0022] Preferably, the second parallel capacitor is a MIM flat plate capacitor.

[0023] Preferably, the first series capacitor, the first parallel capacitor and the second parallel capacitor have their equivalent electrical lengths equal to the even-mode electrical length of the broadband balun by adjusting the capacitance values.

[0024] The present invention has the following beneficial effects:

[0025] The present invention uses lumped capacitance to load a distributed structure balun, so that a transmission line shorter than a quarter wavelength can be used to operate in the same frequency band, thereby achieving miniaturization; and also introduces a series coupling line to adjust the phase and amplitude balance of the main part of the balun within the passband range, so that the design has smaller phase imbalance and amplitude imbalance than the balun in the same frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of an equivalent circuit of a miniaturized broadband balun based on IPD technology;

[0027] Figure 2 A schematic diagram of a miniaturized broadband balun circuit layout based on IPD technology;

[0028] Figure 3 It is a schematic diagram of the cross section of the balun main body coupling line;

[0029] Figure 4 Schematic diagram of the cross section of the coupled line when there is an additional ground microstrip line;

[0030] Figure 5 It is a schematic diagram of the near-band response curve of the present invention;

[0031] Figure 6 It is a schematic diagram of a phase imbalance curve of the present invention;

[0032] Figure 7 It is a schematic diagram of the amplitude imbalance curve of the present invention.

[0033] The accompanying drawings are denoted as follows:

[0034] 1-first input port; 2-second input port; 3-third input port; CS1-first series capacitor; CP1-first parallel capacitor; CP2-second parallel capacitor; TL1-first transmission line; TL2-second transmission line; TL3-third transmission line; TL4-fourth transmission line; TL5-fifth transmission line; TL6-sixth transmission line; M1-first microstrip line; M2-second microstrip line; M3-third microstrip line; M4-fourth microstrip line; M5-fifth microstrip line; M6-sixth microstrip line; G1-first ground terminal; G2-second ground terminal; G3-third ground terminal; G4-fourth ground terminal. DETAILED DESCRIPTION

[0035] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0036] Reference Figure 1 and Figure 2 , an embodiment of the present invention provides a miniaturized broadband balun based on IPD process, comprising:

[0037] a first transmission line, a second transmission line, a third transmission line, a fourth transmission line, a fifth transmission line, and a sixth transmission line;

[0038] One end of the second transmission line is connected to the first input port, and the other end of the second transmission line is connected to one end of the fifth transmission line; the other end of the fifth transmission line is connected to one end of the sixth transmission line, and the fifth transmission line and the sixth transmission line are coupled to each other; the other end of the sixth transmission line is connected to one end of the fourth transmission line; the other end of the fourth transmission line is connected to the second ground terminal via a first series capacitor;

[0039] One end of the first transmission line is connected to the second input port, the other end of the first transmission line is connected to the first ground terminal, and the first transmission line and the second transmission line are coupled to each other; the second input port is connected to the third ground terminal via the first parallel capacitor;

[0040] One end of the third transmission line is connected to the third input port, the other end of the third transmission line is grounded, and the third transmission line is coupled to the fourth transmission line; the second input port is connected to the fourth ground terminal via a second parallel capacitor.

[0041] In this embodiment, a balun with a distributed structure is loaded by using a lumped capacitor, so that a transmission line shorter than a quarter wavelength can be used in the same frequency band, thereby achieving miniaturization. The lumped capacitor used in this embodiment includes a first series capacitor CS1, a first parallel capacitor CP1, and a second parallel capacitor CP2. Under even-mode excitation, the center of the coupling line is in an open-circuit state. After the loaded capacitor, its value does not affect the phase velocity of the even mode, and the electrical length under the even mode remains unchanged. Under odd-mode excitation, the center of the coupling line is in an open-circuit state, and the loaded capacitor value affects the phase velocity of the odd mode. Therefore, when the loaded capacitor value is adjusted to a suitable range, its equivalent electrical length can be equal to the even-mode electrical length to achieve miniaturization and effectively compensate for the performance of the balun, such as the amplitude and phase balance.

[0042] In addition, this embodiment also introduces a series coupling line to adjust the balance of the phase and amplitude of the main part of the balun within the passband range, so that the design has a smaller phase imbalance and amplitude imbalance compared with the balun in the same frequency band. The series coupling line used in this embodiment includes a fifth transmission line TL5 and a sixth transmission line TL6; for a simple four-port transmission line model, its even-mode circuit is analyzed, and the even-mode condition is determined to be: power is not transmitted from the unbalanced port 1 to the balanced port 2, so that the required size of the additional series coupling line can be calculated from the operating frequency and impedance of the quarter-wavelength coupling line to achieve the required improved imbalance.

[0043] In an optional embodiment of the present invention, the embodiment further includes:

[0044] a first microstrip line, a second microstrip line, and a third microstrip line;

[0045] One end of the first microstrip line is connected to one end of the second microstrip line, the connecting end of the first microstrip line and the second microstrip line is connected to a third ground end via a third microstrip line, and the first microstrip line and the second microstrip line are coupled to each other.

[0046] This embodiment also includes:

[0047] a fourth microstrip line, a fifth microstrip line, and a sixth microstrip line;

[0048] One end of the fourth microstrip line is connected to one end of the fifth microstrip line, the connecting end of the fourth microstrip line and the fifth microstrip line is connected to the fourth ground end through the sixth microstrip line, and the fourth microstrip line and the fifth microstrip line are coupled to each other.

[0049] In this embodiment, the line widths of the first microstrip line and the second microstrip line are greater than the line widths of the fourth microstrip line and the fifth microstrip line.

[0050] This embodiment adjusts the coupling degree and imbalance degree of the balun main part by introducing an additional ground microstrip line. This embodiment uses an additional ground microstrip line including a first microstrip line M1, a second microstrip line M2, a third microstrip line M3, a fourth microstrip line M4, a fifth microstrip line M5, a sixth microstrip line M6, a first ground terminal G1, and a second ground terminal G2.

[0051] This embodiment introduces an additional ground microstrip line to increase the capacitance between the balun body and the microstrip line, so the coupling coefficient of the balun body will be reduced due to the effect of the additional ground microstrip line. Therefore, when the balun coupling coefficient is large, this method can be used to adjust the coupling degree, such as Figure 5 shown.

[0052] Reference Figure 3 and Figure 4 , Figure 3Where Cm represents the capacitance between the two microstrip lines, CS1 and CS2 represent the capacitance of the two microstrip lines to the ground, so the coupling coefficient Ko of the two microstrip lines can be simply expressed as:

[0053]

[0054] When an additional ground microstrip line is added, the capacitance generated by the balun main microstrip line to the additional ground microstrip line is CS3 and CS4. Therefore, the coupling coefficient Ka of the two microstrip lines can be simply expressed as:

[0055]

[0056] Since the capacitors CS3 and CS4 are larger than the capacitors CS1 and CS2, Ka is smaller than Ko, which reduces the coupling coefficient between the microstrip lines of the balun body after adding the additional ground microstrip line.

[0057] Since the first series capacitor CS1 and the second ground terminal G2 are connected to the fourth transmission line TL4, the two sections of the balun body are not completely symmetrical, so the coupling coefficients K1 and K2 of the two sections of the balun body are slightly different, and the coupling coefficient K1 is slightly larger than the coupling coefficient K2. Therefore, the line width of the first microstrip line M1 and the second microstrip line M2 is slightly wider than the third microstrip line M3 and the fourth microstrip line M4, which can reduce the difference between the adjusted coupling coefficients K1 and K2, thereby improving the imbalance. Therefore, the additional ground microstrip line reduces the phase imbalance and amplitude imbalance of the balun to a certain extent, such as Figure 6 and Figure 7 shown.

[0058] The present invention constructs a marchand coupling structure with different layers of metal and staggers them in the horizontal direction to reduce coupling and thus reduce the size of the part.

[0059] In an optional embodiment of the present invention, the broadband balun of this embodiment is constructed using an IPD process.

[0060] Among them, the substrate material of the broadband balun is gallium arsenide.

[0061] Wherein, the first series capacitor is a MIM flat plate capacitor.

[0062] Wherein, the first parallel capacitor is a MIM flat plate capacitor.

[0063] Wherein, the second parallel capacitor is a MIM flat plate capacitor.

[0064] This embodiment uses the IPD process to implement a broadband balun, which makes the design more flexible in routing and higher in integration, and can be integrated with other devices to achieve different performances. The IPD process based on gallium arsenide is suitable for building miniaturized microwave devices because of its higher electron mobility and lower dielectric loss. The IPD process can combine lumped parameter components and distributed parameter components, and has higher stability and reliability.

[0065] The broadband balun based on the IPD process of the present invention is composed of a substrate, three MIM flat plate capacitors CP1, CP2, CP3, six transmission lines TL1, TL2, TL3, TL4, TL5, TL6, four ground terminals G1, G2, G3, G4 and the like.

[0066] The broadband balun based on the IPD process proposed in the present invention adopts a method for improving the phase and amplitude imbalance within the passband.

[0067] The signal flows in from the first input port 1, flows through the second transmission line TL2, the fifth transmission line TL5, the sixth transmission line TL6, and flows into the fourth transmission line TL4, then flows through the first series capacitor CS1 and connects to the second ground terminal G2. The fifth transmission line TL5 and the sixth transmission line TL6 are coupled to each other. The second transmission line TL2 is coupled with the first transmission line TL1, the first microstrip line M1 and the second microstrip line M2 respectively. The fourth transmission line TL4 is coupled with the third transmission line TL3, the fourth microstrip line M4 and the fifth microstrip line M5 respectively.

[0068] The signal flows into the first input port 2 and is divided into two paths, one path is connected to the ground through the first parallel capacitor CP1, and the other path is connected to the third ground terminal G3 through the first transmission line TL1. The first transmission line TL1 and the second transmission line TL2, the first microstrip line M1 and the second microstrip line M2 are coupled to each other.

[0069] The signal flows into the first input port 3 and is divided into two paths, one path is connected to the ground through the second parallel capacitor CP2, and the other path is connected to the second ground terminal G2 through the third transmission line TL3. The fourth transmission line TL4 is coupled with the third transmission line TL3, and the fourth microstrip line M4 is coupled with the fifth microstrip line M5.

[0070] The first microstrip line group includes a first microstrip line M1, a second microstrip line M2 and a third microstrip line M3. After the first microstrip line M1 and the second microstrip line M2 receive signals from the first transmission line TL1 and the second transmission line TL2, the signals flow through the third microstrip line M3 and are connected to the third ground terminal G3.

[0071] The second microstrip line group includes a fourth microstrip line M4, a fifth microstrip line M5 and a sixth microstrip line M6. After receiving the signal from the third transmission line TL3 and the fourth transmission line TL4, the signal flows through the sixth microstrip line M6 and then connects to the fourth ground terminal G4.

[0072] The broadband balun based on IPD technology proposed in the present invention uses gallium arsenide as the substrate material, the designed frequency band is (6GHz-14 GHz), and the center frequency is 10GHz. The physical size of the filter is 690um*800um. The maximum loss in the passband is 4.38dB, and the echo is better than -15dB. The amplitude imbalance in the passband is better than 0.213dB, and the phase imbalance is better than 0.137°.

[0073] Based on the above performance analysis, it can be concluded that the IPD hybrid broadband balun chip provided by the present invention has the characteristics of small size, high selectivity, and low phase and amplitude imbalance. This makes the present invention more advantageous than other similar products on the market, which is conducive to large-scale production and application.

[0074] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0075] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A miniaturized broadband balun based on IPD technology, characterized in that: include: a first transmission line, a second transmission line, a third transmission line, a fourth transmission line, a fifth transmission line, and a sixth transmission line; One end of the second transmission line is connected to the first input port, and the other end of the second transmission line is connected to one end of the fifth transmission line; the other end of the fifth transmission line is connected to one end of the sixth transmission line, and the fifth transmission line and the sixth transmission line are coupled to each other; the other end of the sixth transmission line is connected to one end of the fourth transmission line; the other end of the fourth transmission line is connected to the second ground terminal via a first series capacitor; One end of the first transmission line is connected to the second input port, the other end of the first transmission line is connected to the first ground terminal, and the first transmission line and the second transmission line are coupled to each other; the second input port is connected to the third ground terminal via the first parallel capacitor; One end of the third transmission line is connected to the third input port, the other end of the third transmission line is grounded, and the third transmission line is coupled to the fourth transmission line; the second input port is connected to the fourth ground terminal via a second parallel capacitor.

2. The miniaturized broadband balun based on IPD process according to claim 1, characterized in that: Also includes: a first microstrip line, a second microstrip line, and a third microstrip line; One end of the first microstrip line is connected to one end of the second microstrip line, the connecting end of the first microstrip line and the second microstrip line is connected to a third ground end via a third microstrip line, and the first microstrip line and the second microstrip line are coupled to each other.

3. The miniaturized broadband balun based on IPD process according to claim 2, characterized in that: Also includes: a fourth microstrip line, a fifth microstrip line, and a sixth microstrip line; One end of the fourth microstrip line is connected to one end of the fifth microstrip line, the connecting end of the fourth microstrip line and the fifth microstrip line is connected to the fourth ground end through the sixth microstrip line, and the fourth microstrip line and the fifth microstrip line are coupled to each other.

4. The miniaturized broadband balun based on IPD process according to claim 3, characterized in that: The line widths of the first microstrip line and the second microstrip line are greater than those of the fourth microstrip line and the fifth microstrip line.

5. The miniaturized broadband balun based on IPD process according to claim 1, characterized in that: The broadband balun is constructed using the IPD process.

6. The miniaturized broadband balun based on IPD process according to claim 5, characterized in that: The substrate material of the broadband balun is gallium arsenide.

7. The miniaturized broadband balun based on IPD process according to claim 5, characterized in that: The first series capacitor is a MIM flat plate capacitor.

8. The miniaturized broadband balun based on IPD process according to claim 5, characterized in that: The first parallel capacitor is a MIM flat plate capacitor.

9. The miniaturized broadband balun based on IPD process according to claim 5, characterized in that: The second parallel capacitor is a MIM flat plate capacitor.

10. The miniaturized broadband balun based on IPD process according to claim 1, characterized in that: The first series capacitor, the first parallel capacitor and the second parallel capacitor have their equivalent electrical lengths made equal to the even-mode electrical length of the broadband balun by adjusting the capacitance values.

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