Compact transformer power combining network

Abstract

The present invention relates to the technical field of wireless communications, and in particular to a compact transformer power combining network. The transformer power combining network of the present invention is composed of two primary inductors, two secondary inductors, and two resonant inductors. The primary inductors and the secondary inductors correspond to coupling coils of a transformer, and are used for realizing the functions of impedance matching, power combining, and differential-to-single-ended conversion. The resonant inductors are connected between the differential primary inductors, and are used for realizing the functions of eliminating the parasitic capacitance power loss and enhancing the electromagnetic coupling. The structure of the compact transformer power combining network is in a symmetrical form: two transformer cores are symmetrically arranged left and right. The transformer power combining network can enhance the electromagnetic induction, decreases the area required by the inductors, and reduces the circuit costs, i.e., having the advantages of low loss and low costs, and is applicable to communication applications with high carrier frequencies such as WLAN and 5G.

Description

Compact Transformer Power Combining Network Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to a compact transformer power synthesis network. Background Art

[0002] The rapid development of wireless communication technology has greatly improved productivity and quality of life. Smartphones and tablets supporting 2G / 3G / 4G / 5G mobile communications, wireless local area networks (WLAN), Bluetooth, and other applications have become standard equipment in people's work and daily lives. As the user experience of electronic devices improves, the demand for data transmission rates is increasing. Wireless communications are moving towards higher carrier frequencies to support wider bandwidths. For example, the 802.11ax standard supports a 5 GHz carrier frequency, and the corresponding channel bandwidth has increased from 40 MHz in 802.11n to 160 MHz. Higher operating carrier frequencies increase the design complexity of circuits such as transmitters in wireless communications. Generally, at higher operating carrier frequencies, the impact of circuit parasitic parameters on performance becomes more pronounced. In particular, parasitic capacitance decreases in impedance at high frequencies, resulting in increased ground losses and significantly reducing circuit efficiency.

[0003] Passive circuits in transmitter circuits perform load impedance matching, output power combining, and differential-to-single-ended conversion, making them crucial components of transmitter circuits. The efficiency of these passive circuits directly determines the overall transmitter circuit's efficiency and performance, and the impact of these parasitic parameters is particularly pronounced. Furthermore, these circuits occupy a significant area. Therefore, optimizing these parasitic parameters to improve efficiency and other performance while minimizing circuit cost is a key and challenging aspect of passive design.

[0004] Currently, domestic and international academic and industrial communities have proposed a number of solutions for passive circuit design, typically using transformer combiners. These can be categorized as series combined transformers and parallel combined transformers. Series combined transformers require more than one transformer core, thus occupying a larger area. Parallel combined transformers require only one transformer core, reducing area requirements but requiring a higher impedance conversion ratio between the primary and secondary inductors, often resulting in reduced efficiency. Furthermore, these methods do not provide any special treatment for parasitic capacitance.

[0005] Summary of the Invention

[0006] In view of the above problems, the present invention aims to provide a low-loss, low-cost, compact transformer power combining network.

[0007] The transformer power synthesis network proposed in the present invention consists of two primary inductors, two secondary inductors, and two resonant inductors. The primary and secondary inductors correspond to the coupled coils of the transformer, completing the functions of impedance matching, power synthesis, and differential-to-single-ended conversion. The resonant inductor is connected between the differential primary inductors to eliminate power loss caused by parasitic capacitance.

[0008] In the transformer power synthesis network, the first primary inductor is connected to the positive output end of the first differential power amplifier PA1 and the negative output end of the second differential power amplifier PA2; the second primary inductor is connected to the positive output end of the second differential power amplifier PA2 and the negative output end of the first differential power amplifier PA1; the first differential power amplifier PA1 and the second differential power amplifier PA2 can be implemented in an analog or digital manner; the first primary inductor is coupled to the first secondary inductor, and the second primary inductor is coupled to the second secondary inductor, and the first secondary inductor and the second secondary inductor are connected in series or in parallel to achieve power synthesis output; the first resonant inductor and the second resonant inductor are respectively connected to the differential ends of the first primary inductor and the second primary inductor to eliminate the power loss of parasitic capacitance.

[0009] When implementing the resonant inductor, it is stacked above or below the original primary and secondary inductors to avoid occupying excess area. At the same time, by designing the current directions between the first primary inductor, the second primary inductor, and the resonant inductor to be the same, the electromagnetic coupling between the inductors is enhanced, thereby reducing losses and further reducing the circuit area.

[0010] The transformer power combining network of the present invention is symmetrical: the two transformer cores are implemented in a bilaterally symmetrical manner, with the first and second primary inductors exhibiting symmetry, as well as the first and second resonant inductors exhibiting symmetry, thereby ensuring good linearity. The currents in the two transformer cores flow in the same direction between the first, second, and resonant inductors, enhancing electromagnetic field, improving the quality factor of the primary inductors of the power combining network, reducing losses, and facilitating area cost reduction.

[0011] Compared with traditional transformer synthesizers, the transformer power synthesis network of the present invention adds a resonant inductor between the differential primary inductors to eliminate the power loss caused by parasitic capacitance. When realizing the resonant inductor, it is stacked above or below the original primary and secondary inductors, while avoiding occupying excess area, the electromagnetic coupling between the inductors is enhanced; there is quantitative coupling between the resonant inductor and the primary and secondary inductors. By designing the current direction to make it in the same direction, the electromagnetic induction can be enhanced, thereby reducing the area required for the inductor and reducing the circuit cost. The transformer power synthesis network proposed by the present invention has the characteristics of low loss and low cost, and is suitable for high carrier frequency communication applications such as WLAN and 5G. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram of the transformer power synthesis network structure.

[0013] Figure 2 shows an example of how a transformer power combining network is implemented. DETAILED DESCRIPTION

[0014] As shown in Figure 1, the compact transformer power combining network proposed in the present invention consists of a primary inductor, a secondary inductor, and a resonant inductor. PA1 and PA2 are two differential power amplifiers that can be implemented in either analog or digital mode. Primary inductor 1 connects the positive output terminal of PA1 and the negative output terminal of PA2; primary inductor 2 connects the positive output terminal of PA2 and the negative output terminal of PA1. Primary inductor 1 is coupled to secondary inductor 1, and primary inductor 2 is coupled to secondary inductor 2. Secondary inductors 1 and 2 are connected in series to achieve power combining output. Resonant inductor 1 and resonant inductor 2 connect the differential primary inductor 1 and primary inductor 2 at their respective ends. When implementing the resonant inductor, it is stacked above or below the existing primary and secondary inductors to avoid occupying excess area. By designing the currents in primary inductor 1, primary inductor 2, and resonant inductor to align, electromagnetic coupling between the inductors is enhanced, thereby reducing losses and further reducing circuit area.

[0015] This transformer combiner can be implemented in multiple ways. Figure 2 shows a symmetrical implementation based on series combination. Primary inductor 1 is coupled to secondary inductor 1, and primary inductor 2 is coupled to secondary inductor 2. Secondary inductors 1 and 2 are connected in series to achieve power combination output. Resonant inductor 1 and resonant inductor 2 connect the differential primary inductors 1 and 2 at both ends, respectively. The two transformer cores are implemented in a bilaterally symmetrical manner. Primary inductor 1 and primary inductor 2 are symmetrical, and resonant inductor 1 and resonant inductor 2 are symmetrical, which helps ensure good linearity. In the two transformer cores, the currents between primary inductor 1, primary inductor 2, and resonant inductor are in the same direction, which is used to enhance electromagnetic field, improve the primary inductor quality factor of the power combination network, reduce losses, and help reduce area cost.

[0016] Therefore, the present invention proposes a low-loss, low-cost transformer power synthesis network that eliminates the power loss caused by parasitic capacitance by adding a parallel resonant inductor between the differential primary inductors. When implementing the resonant inductor, it is stacked above or below the original primary and secondary inductors, thereby enhancing the electromagnetic coupling between the inductors while avoiding occupying excess area, thereby further reducing the circuit area. Therefore, the transformer power synthesis network proposed by the present invention has a simple structure and a compact area, making it suitable for high-carrier frequency communication applications such as WLAN and 5G.

Claims

1. A compact transformer power synthesis network, characterized in that: It consists of two primary inductors, two secondary inductors, and two resonant inductors. The primary inductors and secondary inductors correspond to the coupling coils of the transformer, completing the functions of impedance matching, power synthesis, and differential to single-ended conversion. The resonant inductor is connected between the differential primary inductors to eliminate the power loss caused by parasitic capacitance. Its structure is symmetrical: the two transformer cores are implemented in a bilaterally symmetrical manner, the first primary inductor and the second primary inductor are symmetrical, and the first resonant inductor and the second resonant inductor are symmetrical; specifically: The first primary inductor is connected to the positive output end of the first differential power amplifier PA1 and the negative output end of the second differential power amplifier PA2; the second primary inductor is connected to the positive output end of the second differential power amplifier PA2 and the negative output end of the first differential power amplifier PA1; the first differential power amplifier PA1 and the second differential power amplifier PA2 are implemented in an analog or digital manner; the first primary inductor is coupled to the first secondary inductor, the second primary inductor is coupled to the second secondary inductor, the first secondary inductor and the second secondary inductor are connected in series or in parallel to achieve power synthesis output; the first resonant inductor and the second resonant inductor are respectively connected to the differential ends of the first primary inductor and the second primary inductor to eliminate the power loss of parasitic capacitance.

2. The compact transformer power synthesis network according to claim 1, characterized in that: When realizing the resonant inductor, it is stacked above or below the original primary and secondary inductors to avoid occupying excess area. At the same time, the current directions between the first primary inductor, the second primary inductor, and the resonant inductor are designed to be the same to enhance the electromagnetic coupling between the inductors, thereby reducing losses and reducing the circuit area.

3. The compact transformer power synthesis network according to claim 1, characterized in that: In the two transformer cores, the current directions among the first primary inductor, the second primary inductor and the resonant inductor are the same, so as to enhance electromagnetics, improve the primary inductor quality factor of the power synthesis network, reduce losses, and reduce area costs.

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