CN111292922B

CN111292922B - 8-shaped four-way power combiner with low insertion loss

Info

Publication number: CN111292922B
Application number: CN202010095802.0A
Authority: CN
Inventors: 康凯; 黄成熊; 吴韵秋; 赵晨曦; 刘辉华; 余益明
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2020-02-17
Filing date: 2020-02-17
Publication date: 2022-03-15
Anticipated expiration: 2040-02-17
Also published as: CN111292922A

Abstract

The invention belongs to the technical field of communication, relates to a power synthesizer, and particularly provides a novel 8-shaped four-way power synthesizer with low insertion loss; the method is used for solving the problems that the traditional 8-shaped (eight-shaped) transformer power combiner has larger insertion loss, deteriorates the overall performance of a circuit and has inconsistent input port impedance in multipath synthesis. According to the invention, through the improvement of the traditional 8-shaped power combiner, the secondary coil of the traditional 8-shaped transformer is split into two 8-shaped coils which are symmetrical about the signal direction, and a mutual nested structure that two circles of secondary coils sandwich the primary coil is adopted, so that the energy leakage is less, the coupling coefficient is higher, the area is effectively reduced, and the design of high-bandwidth and low-insertion-loss power combination is favorably realized; meanwhile, the unique physical structure ensures the characteristic of high consistency of input impedance of each port of the power combiner.

Description

8-shaped four-way power combiner with low insertion loss

Technical Field

The invention belongs to the technical field of communication, relates to a power combiner, and particularly relates to an 8-shaped four-way power combiner with low insertion loss.

Background

It is well known that the higher the operating frequency of a communication system, the faster the signal transmission rate and the greater the channel capacity can be provided. Due to the occupation of spectrum resources, the 5th generation mobile communication (5G) cellular network communication with high throughput is supported by adopting 24.75-27.5 GHz and 37-42.5 GHz mobile millimeter wave broadband systems of K/Ka bands. Silicon-based rf ic fabrication processes are of interest for their excellent performance and inexpensive cost. BiCMOS transistors do not have the effect of the body effect and therefore can provide relatively higher linearity than MOSFETs. Compared with the III-V group compound semiconductor process, the silicon-based circuit not only has very low manufacturing cost, but also can be integrated with a digital circuit, and has very important research value.

Of NPN transistors in integrated circuitsβ _FThe maximum can reach 500, so that the high-performance transistor HP NPN can provide relatively higher gain, and therefore higher PAE (power added efficiency) is realized, and the high-performance transistor HP NPN has excellent high-frequency characteristics; however, due to the limitation of the reliability of the silicon-based process, compared with the III-V group process, the power supply voltage and the current density of the radio frequency power amplifier are relatively small, so that the output power of a single tube of a silicon-based transistor is limited; in order to increase the output power of the power amplifier, a multi-path power combining method may be used. The power synthesis technology includes methods such as on-chip power synthesis and space power synthesis. At millimeter wave frequencies, the on-chip power synthesis technology is widely applied, and the main results include: direct power combining, wilkinson power combining, and transformer-based power combining. Direct power synthesis directly synthesizes currents from multiple channels and applies them to an output load to obtain high power, but impedance transformation networks may result in large losses and asymmetric layouts; wilkinson power synthesis based on transmission lines can realize good isolation and matching for all ports under specified frequency, but is only suitable for narrow-band application, is sensitive to coupling and element parasitic effects, and occupies a large amount of chip area in a millimeter wave frequency band; the power synthesis based on the transformer integrates the functions of power synthesis and impedance matching, and the loss of a passive network is not additionally increased, so that the power synthesis based on the transformer is widely applied to improving the power output capability of a circuit.

In the traditional transformer multipath power synthesis, an independent multi-transformer current synthesis method is often adopted, so that the output power of a power amplifier is improved. Each transformer has high coupling coefficient and low insertion loss, but in the case of the current synthesis method adopting independent transformers, more loss is introduced to a certain extent due to the use of the independent transformers; meanwhile, mutual influence exists among the transformers, and the problem of inconsistency of impedance of each port exists, and the power combiner has the functions of power combination and impedance transformation at the same time, so the loss of the power combiner can be influenced to a great extent by the quality of impedance matching; when the impedance matching of the matching network is poor, a part of the energy consumption is consumed due to the impedance discontinuity.

The conventional 8-shaped (right-shaped) transformer power combiner structure is shown in fig. 4, in which the primary coil and the secondary coil are both independent single-turn structures, and the above-mentioned problem still exists. Meanwhile, the impedance of the input port of the power synthesizer is inconsistent due to the inconsistency of the output ports and the inconsistency of the signal paths, and the impedances of the four input ends are not equal at the moment; to overcome this problem, the diameters of the octagonal coils on the left and right sides of the power combiner shown in fig. 4 may not be equal, so as to increase the input impedance consistency of the power combiner; this approach, however, increases the design difficulty of the synthesizer network and increases its insertion loss, while possibly introducing other problems.

Disclosure of Invention

The invention aims to solve the problems that the traditional 8-shaped (edge-shaped) transformer power combiner has larger insertion loss, deteriorates the overall performance of a circuit and has inconsistent input port impedance in multipath synthesis; a figure-8 power combiner architecture with low insertion loss is provided. The 8-shaped power combiner structure has high symmetry, less energy leakage and effectively increased dead-against area of the primary and secondary coils, so that the coupling coefficient of the power combining transformer is relatively high, and the insertion loss problem of a power combining network is effectively improved; the problem of inconsistent input port impedance of the traditional transformer power combiner is also effectively solved.

In order to achieve the purpose, the invention adopts the technical scheme that:

a8-shaped four-way power combiner with low insertion loss is composed of a primary coil and two secondary coils; the single-phase motor is characterized in that the primary coil is formed by two paths of inputs which are mirror-symmetrical about a middle cross point, and an 8-shaped primary coil is formed together; the two secondary coils are 8-shaped secondary coils formed by two octagons with one large side and one small side, the two 8-shaped secondary coils are placed in a mirror image mode about a middle cross point to form a mutual nesting structure of a large ring and a small ring, and the 8-shaped primary coil is located between the large ring and the small ring of the mutual nesting structure.

Furthermore, in the power combiner, the cross connection is realized at the Chinese knot where the coils cross by adopting the secondary layer metal.

The invention has the beneficial effects that:

the invention provides an improved 8-shaped four-way power combiner with low insertion loss, which is characterized in that a secondary coil of a traditional 8-shaped transformer is split into two 8-shaped coils which are symmetrical relative to the signal direction through the improvement of the traditional 8-shaped power combiner, and a mutual nesting structure that two circles of secondary coils clamp a primary coil is adopted, so that the improved 8-shaped four-way power combiner has less energy leakage and higher coupling coefficient, effectively reduces the area, and is beneficial to realizing the power combining design with high bandwidth and low insertion loss; meanwhile, the unique physical structure ensures the characteristic of high consistency of input impedance of each port of the power combiner.

Drawings

Fig. 1 is a schematic diagram of a winding topology of a 8-shaped four-way power combiner with low insertion loss according to the present invention.

Fig. 2 shows a 8-shaped four-way power synthesizer HFSS model with low insertion loss according to the present invention.

Fig. 3 shows the input impedance of the inventive figure-8 four-way power combiner with low insertion loss, wherein (a) is the real part of the impedance and (b) is the imaginary part of the impedance.

Fig. 4 is a schematic diagram of a conventional 8-shaped power combiner.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

In order to solve the problems of the conventional 8-shaped power combiner, the invention provides an 8-shaped power combiner, the structure of which is shown in fig. 1; the primary and secondary coils of the power combiner adopt top layer metal with minimum loss to the maximum extent, the secondary coil of the traditional 8-shaped transformer is split into two 8-shaped coils which are symmetrical relative to the signal direction, and the primary coil is clamped between the two secondary coils to achieve the effect of improving the coupling coefficient.

More specifically: in the embodiment, two paths of input primary coils of power synthesis are in mirror symmetry with respect to a middle cross point to form an 8 shape together; the two secondary coils form an 8 shape by two octagons with a big end and a small end respectively, the two corresponding 8-shaped secondary coils are placed in a mirror image mode about a middle cross point to form a mutual nesting structure of a big ring and a small ring, and the primary coil is positioned in the middle of the big ring and the small ring which are nested with each other; an 8-shaped primary coil and two 8-shaped secondary coils are mutually nested, and cross connection is realized at a Chinese knot part crossed in the middle by using secondary layer metal; the 3 figure-8 coils together form a figure-8 power combiner.

The electromagnetic fields formed by any one of the left octagonal coils and the right octagonal coils of the 8-shaped power synthesizer are equal in amplitude, the polarities of the electromagnetic fields of the two octagons in each 8-shaped coil are opposite, and the electromagnetic fields outside the coils can be mutually offset to a certain extent. Due to the 8-shaped compact mutual nesting structure, the facing area of the primary and secondary coils can be improved to the maximum extent, and the coupling coefficient is improved. In addition, due to the mirror symmetry structure, the distribution of the parasitic capacitance between the primary and secondary coils is also symmetrical with respect to the signal direction, the parasitic current flowing through the parasitic capacitance will be generated between both sets of the primary and secondary coils, and the distribution of the parasitic current between the secondary and primary coils is also symmetrical because the secondary coil is symmetrical with respect to the signal direction. In addition, the 8-shaped power combiner can improve the impedance consistency of the input ports. In conclusion, the 8-shaped power combiner has less energy leakage and lower insertion loss, thereby improving the efficiency and gain of the amplifier and reducing the interference possibly caused to other circuit modules.

Fig. 3 shows an HFSS model of the figure-8 power combiner, which includes three figure-8 coils, wherein a figure-8 primary coil and two figure-8 secondary coils are nested, and cross-connection is realized at the intersection by using a secondary layer metal; each figure-8 coil contains two octagonal coils.

Fig. 4 shows the input impedance versus frequency curves of the four input ports of the figure-8 power combiner; the real parts of the input impedances of the four ports are maintained between 10 and 15 approximately at 25 to 45GHz, and the imaginary parts of the input impedances are maintained between 10 and 15 at 20 to 42 GHz; this input impedance characteristic indicates that the power combiner provides preconditions and guarantees for proper PA operation in the K, Ka band.

While the invention has been described with reference to specific embodiments, any feature disclosed in this specification may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise; all of the disclosed features, or all of the method or process steps, may be combined in any combination, except mutually exclusive features and/or steps.

Claims

1. A8-shaped four-way power combiner with low insertion loss is composed of a primary coil and two secondary coils; the single-phase motor is characterized in that the primary coil is formed by two paths of inputs which are mirror-symmetrical about a middle cross point, and an 8-shaped primary coil is formed together; the two secondary coils are 8-shaped secondary coils formed by two octagons with one large side and one small side, the two 8-shaped secondary coils are placed in a mirror image mode about a middle cross point to form a mutual nesting structure of a large ring and a small ring, and the 8-shaped primary coil is located between the large ring and the small ring of the mutual nesting structure.

2. The figure-8 four-way power combiner with low insertion loss according to claim 1, wherein in the power combiner, cross-connections are realized by using sub-layer metal at the "chinese junctions" where all coils cross.