Equivalent circuit of low insertion loss broadband balun for base station and balun thereof

Abstract

The utility model discloses a base station uses low insertion loss broadband balun equivalent circuit and its balun, the utility model is based on LTCC (low temperature co-fired ceramic) technology, adopts Marchand structure principle design, realizes 1 / 4 wave length coupling line through the spiral structure of wide edge coupling, greatly reduces the volume of balun, and two groups of coupling transmission lines adopt the folding mode, fully utilizes the three -dimensional wiring advantage of LTCC technology, and the signal shielding cover is carried out in the middle through GND, avoids the crosstalk between two groups of coupling transmission lines, realizes the functional characteristics of new base station use insertion loss small, amplitude flatness is good, phase consistency is high, broadband small size.

Description

Technical Field

[0001] This utility model discloses a novel miniaturized, low-insertion-loss, wideband balun for base stations, applicable to base station wireless communication equipment, specifically relating to an equivalent circuit of a low-insertion-loss, wideband balun for base stations and the balun thereof. Background Technology

[0002] Low-Temperature Co-fired Ceramic (LTCC), as a widely applicable high-density packaging technology, has become the preferred method for the integration of future electronic components due to its excellent electronic, mechanical, and thermal properties. RF microwave components and modules designed and manufactured based on LTCC technology include baluns, filters, balun filters, duplexers, multiplexers, couplers, power dividers, antennas, receiver front-end modules, and antenna switch modules. Besides advantages in cost and integrated packaging, LTCC also offers many advantages in wiring linewidth and spacing, low-impedance metallization, design versatility, and high-frequency performance. As modern electronic devices continue to evolve towards miniaturization and higher frequencies, LTCC is now widely used in various electronic devices.

[0003] A balun, as a balanced-to-unbalanced converter, is an important component in a base station radio frequency transceiver system. As a three-port device, it includes one unbalanced port and two balanced ports. Generally, the signal is input from the unbalanced port and output from the two balanced ports. The output signals from the two balanced ports have the same amplitude and are 180° out of phase, which can effectively improve the system's anti-interference capability.

[0004] Traditional microstrip coupled-line circuits are used in typical RF balun designs, which not only occupy a large PCB area but also involve complex debugging. In contrast, chip RF multilayer baluns designed and fabricated using LTCC technology offer superior performance, small size, light weight, simple surface mounting, convenient debugging, low cost, and suitability for mass production. Utility Model Content

[0005] This utility model provides a novel low insertion loss, wideband balun for base stations. The balun is structurally designed using the classic Marchand balun principle and employs LTCC technology, being manufactured through low-temperature co-firing at approximately 900°C. The technical solution adopted by this utility model to solve its technical problem is as follows:

[0006] A low insertion loss broadband balun equivalent circuit for a base station includes a first set of coupled transmission lines and a second set of coupled transmission lines. The first set of coupled transmission lines includes a first inductor L1 and a third inductor L3, and the second set of coupled transmission lines includes a second inductor L2 and a fourth inductor L4. One end of the first inductor L1 is the unbalanced input of the balun, and the other end is connected to the second inductor L2, while the other end of the second inductor L2 is left open. One end of the third inductor L3 is grounded, and the other end is the first balanced output of the balun. One end of the fourth inductor L4 is grounded, and the other end is the second balanced output of the balun.

[0007] This utility model provides a low insertion loss broadband balun for base stations. The balun includes a ceramic substrate, a terminal block disposed on the outside of the substrate, and a seven-layer circuit structure in a stacked configuration inside the ceramic substrate, comprising:

[0008] The first layer has a first metal pattern and a second metal pattern printed on a ceramic dielectric substrate. The first metal pattern is connected to the first port P1, the first end of the first metal pattern is connected to the third port P3, and the second end of the first metal pattern is connected to the first internal via.

[0009] The second layer has a second layer of first metal pattern printed on a ceramic dielectric substrate. The first end of the second layer of first metal pattern is connected to the second port P2, and the second end of the second layer of first metal pattern is connected to the first internal via. The first layer of first metal pattern and the second layer of first metal pattern constitute a third inductor L3.

[0010] The third layer has a first metal pattern and a second metal pattern printed on a ceramic dielectric substrate. The first end of the first metal pattern is connected to the first port P1, the second end of the first metal pattern is connected to the second internal via, and the second metal pattern is connected to the third port P3. The first metal pattern forms the first inductor L1.

[0011] The fourth layer has a first metal pattern printed on the ceramic dielectric substrate. The first end of the first metal pattern is connected to the fifth port P5, serving as an isolation layer for the two sets of transmission lines.

[0012] The fifth layer is a first metal pattern printed on a ceramic dielectric substrate. The first end of the first metal pattern is connected to the second port P2, and the second end of the first metal pattern is connected to the second internal via. The first metal pattern forms the second inductor L2.

[0013] The sixth layer is a first metal pattern printed on a ceramic dielectric substrate, wherein the first end of the first metal pattern is connected to the third internal via.

[0014] The seventh layer consists of a first metal coil and a second metal coil printed on a ceramic dielectric substrate. The first end of the first metal coil is connected to the fourth port P4, and the second end of the first metal coil is connected to the third internal via. The first metal pattern of the sixth layer and the first metal coil of the seventh layer together constitute the fourth inductor L4.

[0015] The beneficial effects of this utility model are as follows: Based on LTCC (Low Temperature Co-fired Ceramic) technology and designed using the Marchand structural principle, this utility model achieves an equivalent 1 / 4 wavelength coupling line through a wide-side coupled spiral structure, greatly reducing the volume of the balun. Simultaneously, the two sets of coupled transmission lines are folded, fully utilizing the three-dimensional wiring advantages of LTCC technology. A GND shield is used in the middle to avoid crosstalk between the two sets of coupled transmission lines, achieving the functional characteristics of low insertion loss, good amplitude flatness, high phase consistency, and wide bandwidth with small size for new base stations. The balun product has dimensions of 1.6mm*0.8mm*0.6mm, a passband frequency of 5~10GHz, IL@5~10GHz≤1.0dB, VSWR@5~10GHz≤2.0, amplitude imbalance@5~10GHz≤1.0dB, and phase imbalance@5~10GHz≤10°. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the equivalent circuit of the low insertion loss, wideband balun used in the base station of this utility model;

[0017] Figure 2 This is a three-dimensional schematic diagram of the low insertion loss, wideband balun for base stations according to this utility model;

[0018] Figure 3 This is a schematic diagram of the internal structure of the low insertion loss, wideband balun for base stations according to this utility model;

[0019] Figure 4 The electrical characteristic curve of the low insertion loss, wideband balun used in the base station of this utility model;

[0020] Figure 5 This is a schematic diagram of the first layer circuit planar structure of this utility model;

[0021] Figure 6 This is a schematic diagram of the second-layer circuit planar structure of this utility model;

[0022] Figure 7 This is a schematic diagram of the via connection planar structure between the second and third layers of the circuit in this utility model;

[0023] Figure 8 This is a schematic diagram of the third-layer circuit planar structure of this utility model;

[0024] Figure 9This utility model provides a planar connection for vias between the third, fourth, fourth, and fifth layers of circuitry.

[0025] Schematic diagram;

[0026] Figure 10 This is a schematic diagram of the fourth layer circuit planar structure of this utility model;

[0027] Figure 11 This is a schematic diagram of the fifth layer circuit planar structure of this utility model;

[0028] Figure 12 This is a schematic diagram of the sixth layer circuit planar structure of this utility model;

[0029] Figure 13 This is a schematic diagram of the planar structure of the through-hole connection between the sixth and seventh layers of this utility model;

[0030] Figure 14 This is a schematic diagram of the seventh layer circuit planar structure of this utility model. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] A novel low insertion loss, wideband balun for base stations includes a substrate, a terminal block disposed on the outside of the substrate, and a circuit layer disposed inside the substrate, wherein the circuit layer inside the substrate has a stacked structure.

[0033] Figure 1 This is the equivalent circuit diagram of a new type of low-insertion-loss, wideband balun used in base stations. The balun adopts a Marchand-type structure design and consists of two sets of coupled transmission lines. The first set of coupled transmission lines is formed by the first inductor L1 and the third inductor L3, while the second set is formed by the second inductor L2 and the fourth inductor L4. One end of the first inductor L1 is the unbalanced input of the balun, and the other end is connected to the second inductor L2, while the other end of the second inductor L2 is left open. One end of the third inductor L3 and the fourth inductor L4 are grounded, and the other end serves as the balanced output of the balun.

[0034] Figure 2 It is the appearance structure of a low insertion loss, wideband balun used in base stations. The first port P1, the third port P3, and the fifth port P5 are grounding ports. The second port P2 is the common port of the chip duplexer. The fourth port P4 is the high-frequency bandpass output port. The sixth port P6 is the low-frequency output port. Mark is its direction indicator.

[0035] Figure 4 These are the low insertion loss, wide bandwidth balun electrical characteristic curves for new base stations, where 1 represents the unbalanced port and 2 and 3 represent the balanced ports.

[0036] The new base station uses a low insertion loss, wideband balun internal structure, such as Figure 3 As shown, the circuit structure is distributed inside the ceramic substrate. The circuit structure has a total of 7 layers; please refer to [the diagram / reference]. Figure 5-14 .

[0037] The first layer has a first metal pattern 1-1 and a second metal pattern 1-2 printed on a ceramic dielectric substrate. The first metal pattern 1-2 is connected to the first port P1, the first end 1-1a of the first metal pattern is connected to the third port P3, and the second end 1-1b of the first metal pattern is connected to the first internal via 8.

[0038] The second layer has a second layer first metal pattern 2-1 printed on the ceramic dielectric substrate. The first end 2-1a of the second layer first metal pattern is connected to the second port P2, and the second end 2-1b of the second layer first metal pattern is connected to the first internal via 8. The first layer first metal pattern 1-1 and the second layer first metal pattern 2-1 together constitute the coupling transmission line L3 in the schematic diagram.

[0039] The third layer has a first metal pattern 3-1 and a second metal pattern 3-2 printed on the ceramic dielectric substrate. The first end 3-1a of the first metal pattern is connected to the first port P1, the second end 3-1b of the first metal pattern is connected to the second internal via 9, and the second metal pattern 3-2 is connected to the third port P3. The first metal pattern 3-1 forms the coupling transmission line L1 in the schematic diagram.

[0040] The fourth layer has a first metal pattern 4-1 printed on the ceramic dielectric substrate. The first end 4-1a of the first metal pattern is connected to the fifth port P5, serving as an isolation layer for the two sets of transmission lines in the schematic diagram.

[0041] The fifth layer is a first metal pattern 5-1 printed on a ceramic dielectric substrate. The first end 5-1a of the first metal pattern is connected to the second port P2, and the second end 5-1b of the first metal pattern is connected to the second internal via 9. The first metal pattern 5-1 constitutes the coupling transmission line L2 in the schematic diagram.

[0042] The sixth layer is a first metal pattern 6-1 printed on a ceramic dielectric substrate, wherein the first end 6-1a of the first metal pattern is connected to the third internal via 10.

[0043] The seventh layer consists of a first metal coil 7-1 and a second metal coil 7-2 printed on a ceramic dielectric substrate. The first end 7-1a of the first metal coil is connected to the fourth port P4, and the second end 7-1b of the first metal coil is connected to the third internal via 10. The first metal pattern 6-1 of the sixth layer and the first metal coil 7-1 of the seventh layer together constitute the coupling transmission line L4 in the schematic diagram.

Claims

1. A low insertion loss wideband balun equivalent circuit for base stations, characterized in that, The equivalent circuit includes a first set of coupled transmission lines and a second set of coupled transmission lines. The first set of coupled transmission lines includes a first inductor L1 and a third inductor L3. The second set of coupled transmission lines includes a second inductor L2 and a fourth inductor L4. One end of the first inductor L1 is the unbalanced input terminal of the balun, and the other end is connected to the second inductor L2. The other end of the second inductor L2 is left open. One end of the third inductor L3 is grounded, and the other end is the first balanced output port of the balun. One end of the fourth inductor L4 is grounded, and the other end is the second balanced output port of the balun.

2. A balun that implements the low insertion loss wideband balun equivalent circuit for base stations as described in claim 1, characterized in that, The balun includes a ceramic substrate, a terminal block disposed on the outer side of the substrate, and a seven-layer circuit structure arranged in a stacked manner inside the ceramic substrate, namely: The first layer has a first metal pattern 1-1 and a second metal pattern 1-2 printed on a ceramic dielectric substrate. The first metal pattern 1-2 is connected to the first port P1, the first end 1-1a of the first metal pattern is connected to the third port P3, and the second end 1-1b of the first metal pattern is connected to the first internal via 8. The second layer has a second layer first metal pattern 2-1 printed on a ceramic dielectric substrate. The first end 2-1a of the second layer first metal pattern is connected to the second port P2, and the second end 2-1b of the second layer first metal pattern is connected to the first internal via 8. The first layer first metal pattern 1-1 and the second layer first metal pattern 2-1 constitute the third inductor L3. The third layer has a first metal pattern 3-1 and a second metal pattern 3-2 printed on a ceramic dielectric substrate. The first end 3-1a of the first metal pattern is connected to the first port P1, the second end 3-1b of the first metal pattern is connected to the second internal via 9, and the second metal pattern 3-2 is connected to the third port P3. The first metal pattern 3-1 forms the first inductor L1. The fourth layer has a first metal pattern 4-1 printed on the ceramic dielectric substrate. The first end 4-1a of the first metal pattern is connected to the fifth port P5, serving as an isolation layer for the two sets of transmission lines. The fifth layer is a first metal pattern 5-1 printed on a ceramic dielectric substrate. The first end 5-1a of the first metal pattern is connected to the second port P2, and the second end 5-1b of the first metal pattern is connected to the second internal via 9. The first metal pattern 5-1 forms the second inductor L2. The sixth layer is a first metal pattern 6-1 printed on a ceramic dielectric substrate, wherein the first end 6-1a of the first metal pattern is connected to the third internal via 10. The seventh layer consists of a first metal coil 7-1 and a second metal coil 7-2 printed on a ceramic dielectric substrate. The first end 7-1a of the first metal coil is connected to the fourth port P4, and the second end 7-1b of the first metal coil is connected to the third internal via 10. The first metal pattern 6-1 of the sixth layer and the first metal coil 7-1 of the seventh layer together constitute the fourth inductor L4.

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