A broadband low-loss harmonic control and power combining network design method

Abstract

This invention discloses a broadband low-loss harmonic control and power combining network design method. It can achieve power combining while simultaneously matching the fundamental and second harmonic impedances, improving efficiency and output power. This invention cascades an improved impedance transformation matching network with a power combining network. By simultaneously formulating equations relating the fundamental and second harmonic impedances and setting the real and imaginary parts of both sides of the equations equal, the specific component values ​​of the inductors and capacitors in the improved impedance transformation matching network can be obtained. This invention retains the impedance transformation and power combining functions of existing methods without significantly increasing circuit topology complexity or circuit area. It can simultaneously achieve fundamental and second harmonic impedance matching, thereby controlling the amplitude and phase relationship between the fundamental and second harmonics, reducing harmonic power dissipation, and improving efficiency and output power.

Description

Technical Field

[0001] This invention belongs to the field of solid-state microwave power amplifier technology, specifically relating to a broadband low-loss harmonic control and power combining network design method for improving the efficiency of high-power solid-state microwave power amplifiers. Background Technology

[0002] Microwave power amplifiers are an important component of microwave systems, capable of amplifying weak microwave signals to the required power level. They are typically located at the end of the transmitter and have wide applications in wireless communication, radar, remote sensing, medical electronics, measurement and control, and electronic countermeasures. With the increasing maturity of GaN (gallium nitride) technology, the output power of power amplifiers has also increased significantly. Currently, the output power of a single tube has exceeded 2kW. See reference [Niu Haijun, Yin Jun, Li Jianfeng. Design and implementation of a high-power solid-state power amplifier in the X-band [J]. Communications World, 2024, 31(07): 54-56].

[0003] To achieve impedance matching for high-power dies with minimal impedance and higher power output, pre-matching networks and multi-path power combining networks are required. For example, the literature [Hu Yansheng, Huang Xu, Wang Yi, et al. Design of X-band GaN kilowatt-level power amplifier [J]. Research and Progress in Solid State Electronics, 2023, 43(04):296-301] points out that a four-path combining method is used to improve output efficiency. Each path consists of a die and a T-type LC (inductor-capacitor) pre-matching network at the input and output ends, and then a two-stage power combining network is used to finally achieve impedance matching and a maximum output power of 2000W. However, the power-added efficiency (PAE) is only 37.2%.

[0004] As the output power of microwave power amplifiers increases, harmonic power dissipation becomes increasingly severe. Research has revealed that the third and higher harmonics in high-power microwave power amplifiers are completely short-circuited by drain parasitic capacitance. If the amplitude-phase relationship between the fundamental and second fundamental frequencies can be controlled, efficiency can be further improved. However, traditional impedance matching networks and power combining networks cannot simultaneously match the fundamental and harmonic impedances. This necessitates improvements to traditional impedance matching and power combining networks to simultaneously match the fundamental and second harmonic impedances while retaining the original power combining function. Summary of the Invention

[0005] To address the issues of severe harmonic power dissipation and low efficiency in existing high-power amplifiers due to limitations in operating modes, this invention provides a broadband low-loss harmonic control and power combining network design method for improving the efficiency of high-power solid-state microwave power amplifiers. This method can simultaneously achieve fundamental impedance matching and second harmonic impedance matching to reduce harmonic power dissipation, while also enabling multi-channel power combining.

[0006] A broadband low-loss harmonic control and power combining network design method introduces an additional capacitor into a traditional T-type impedance transformation matching network to form an improved impedance transformation matching network. This network is used to transform the relatively small fundamental and second harmonic impedances at the transistor drain package end into intermediate impedances. Z 1. Achieve impedance matching between the fundamental and harmonic frequencies, and control the relationship between the fundamental and harmonic frequencies; then, utilize a power combining network to adjust the intermediate impedance. Z 1. Complete the port impedance Z The conversion of 2 allows for the synthesis of multiple power streams.

[0007] Furthermore, an additional capacitor is connected in parallel at the output of the traditional T-type impedance transformation matching network to achieve independent adjustment of the second harmonic impedance.

[0008] Furthermore, the improved impedance transformation matching network includes two capacitors. C 3 and C 4 and two inductors L 3 and L 4, of which L One end of 3 is connected to the drain package terminal of the transistor. L The other end of 3 and L 4 and one end C Connect one end of 3. C The other end of 3 is grounded. L The other end of 4 and C Connecting one end of 4 generates an intermediate impedance Z 1, C The other end of 4 is grounded. L 3. C 3 and L 4. Construct a traditional T-type impedance transformation matching network. C 4 represents an additional capacitor.

[0009] Furthermore, the improved impedance transformation matching network satisfies the following equation: in: R 1+ jX 1 and R 2+ jX 2 represents the fundamental impedance and second harmonic impedance of the transistor drain package, respectively. R 11 + jX 11 and R 22 + jX 22These are the fundamental impedance and second harmonic impedance of the intermediate impedance, respectively. ω Angular frequency, j The imaginary unit is used; by solving the above equations simultaneously and ensuring that the real and imaginary parts of both sides are equal, the value of the imaginary unit in the improved impedance transformation matching network can be obtained. L 3 and L Inductance value of 4 and C 3 and C The capacitance value is 4.

[0010] Furthermore, for the dual-path power combining network, a microstrip-based dual-path power combiner is used to convert the input impedance to the output impedance. The dual-path power combiner includes two microstrip lines, one end of which serves as the two input ports of the dual-path power combiner, connected to their respective input impedances (i.e., the intermediate impedances corresponding to the improved impedance transformation matching network). Z 1) The other ends of the two microstrip lines are connected in parallel to the output impedance (i.e., the port impedance). Z 2) The microstrip line is a segment of length... λ / 4 transmission line, λ The characteristic impedance of the microstrip line is the waveguide wavelength. Z C The expression is as follows: in: Z in For input impedance, Z out This is the output impedance.

[0011] Furthermore, for the four-channel power combining network, a two-stage combining topology is adopted. In the first stage of combining, two dual-channel power combiners are used to combine the intermediate impedances of the four channels. Z 1 converted to two-way intermediate impedance Z mid In the second-stage combining process, a dual-channel power combiner is used to combine the two intermediate impedances. Z mid Convert to port impedance Z 2. The impedance transformation ratios of the two impedance transformations should be as similar as possible and satisfy the following relationship: in: Z C1 The characteristic impedance of the microstrip line in the dual-path power combiner used in the first-stage synthesis is given. Z C2 The characteristic impedance of the microstrip line in the dual-path power combiner used for the second-stage synthesis.

[0012] Furthermore, in the first-stage synthesis, the four input ports of the two dual-channel power combiners are connected sequentially by resistors, which can suppress the amplitude and phase differences between the signals to reduce synthesis loss.

[0013] Furthermore, by cascading an improved impedance transformation matching network with a power combining network, this invention enables power combining while achieving broadband low-loss fundamental impedance and second harmonic impedance matching.

[0014] A high-power solid-state microwave power amplifier includes a broadband low-loss harmonic control and power combining network implemented using the above design method.

[0015] This invention retains the impedance transformation and power synthesis functions of existing methods without significantly increasing circuit topology complexity and circuit area. It can also simultaneously achieve fundamental impedance matching and second harmonic impedance matching, thereby controlling the amplitude and phase relationship between the fundamental and second harmonics, reducing harmonic power dissipation, and improving efficiency and output power. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall circuit structure of a broadband low-loss harmonic control and power combining network. In the diagram, RFin represents the radio frequency input terminal, RFout represents the radio frequency output terminal, and HEMT represents a high electron mobility transistor.

[0017] Figure 2 This is a schematic diagram of the improved impedance transformation matching network circuit designed for this invention.

[0018] Figure 3 This is a schematic diagram of a dual-channel power combiner with impedance transformation function designed for this invention.

[0019] Figure 4 This is a schematic diagram of a four-way power combining network structure with impedance transformation function designed for this invention. Detailed Implementation

[0020] To describe the present invention in more detail, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] In the broadband low-loss harmonic control and power combining network of a high-power solid-state microwave power amplifier, the output matching network and input matching network have similar structures and the same design process. Therefore, this implementation method only takes the output matching network as an example. Figure 1 As shown, the output matching network consists of two parts: an output impedance transformation matching network and a power combining network.

[0022] First, an additional capacitor is introduced into the traditional inductor-capacitor-inductor T-type impedance transformation matching network, such as... Figure 2 As shown, this forms an improved impedance transformation matching network, which can transform the relatively small fundamental and second harmonic impedances at the drain package of the transistor. Z out Transformed into intermediate impedance Z 1. The theoretical analysis of the improved output impedance transformation matching network is as follows: Assume the fundamental and second harmonic impedances at the drain package of the transistor. Z out They are respectively R 1+ jX 1 and R 2+ jX 2. Intermediate impedance Z The fundamental and second harmonic impedances of 1 are respectively R 11 + jX 11 and R 22 + jX 22 To achieve the corresponding fundamental and second harmonic impedance conditions, the improved output impedance transformation matching network must satisfy the following equations: By solving the above equations simultaneously and ensuring that the real and imaginary parts of both sides are equal, the inductance in the improved output impedance matching network can be obtained. L 3 and L 4. Capacitor C 3 and C 4. Specific component values.

[0023] This invention also provides a power combining network design method, which enables the power combining network to perform multi-path power combining while simultaneously achieving intermediate impedance. Z 1-port impedance Z The conversion of 2. The theoretical analysis of the power combining network is as follows: For dual-channel power combiners, such as Figure 3 As shown, if we want to achieve impedance switching while simultaneously realizing power combining, Z in Towards Z out The function of transformation, λ / 4 Characteristic impedance of microstrip line TL Z C for: For a four-way power combining network, such as Figure 4As shown, two dual-channel power combiners are needed to convert the four-channel signal into a dual-channel signal, and then a single dual-channel power combiner is used to convert the dual-channel signal into a single channel. This is equivalent to two impedance transformations and power combining operations, ultimately achieving four-channel combining. The small resistance R between the four channels can suppress amplitude and phase differences between the signals to reduce combining losses. The impedance transformation ratios of the two operations should be as similar as possible to increase the matching bandwidth and reduce losses. Let the intermediate impedance of the four-channel power combining network be... Z mid During the first synthesis λ The characteristic impedance of the / 4 microstrip line TL3 is Z C1 During the second synthesis λ The characteristic impedance of the / 4 microstrip line TL4 is Z C2 Then it needs to satisfy: This implementation combines an improved impedance matching network and a power combining network in a cascaded manner, such as... Figure 1 As shown, power combining can be achieved simultaneously with broadband low-loss fundamental impedance and second harmonic impedance matching. Without significantly increasing circuit topology complexity and area, it retains the impedance transformation and power combining functions of existing networks, and can simultaneously achieve fundamental impedance matching and second harmonic impedance matching. This allows for control over the relationship between the fundamental and second harmonics, reducing harmonic power dissipation and improving efficiency.

[0024] Based on the cascaded structure of the improved impedance transformation matching network and the power combining network, this invention further incorporates a finite harmonic control-based operating mode for collaborative circuit design. It should be noted that this operating mode does not exist independently, but requires coordination with the improved impedance transformation matching network and the power combining network of this invention to effectively achieve precise control of the fundamental and second harmonic impedance conditions, thereby fully leveraging their performance advantages.

[0025] To verify the effectiveness of the broadband low-loss harmonic control and power combining network proposed in this invention, we compared and analyzed the traditional operating mode with the operating mode based on finite harmonic control, wherein the operating mode based on finite harmonic control is implemented using the broadband low-loss harmonic control and power combining network of this invention. The output power, device power dissipation, and efficiency, among other key indicators, were compared between the two operating modes, and the results are shown in Table 1. Table 1 As shown in Table 1, under the operating state based on finite harmonic control using the network structure of this invention, the second harmonic power participates in the output process, with a power of 19.9W; simultaneously, the device power dissipation decreases from 217.0W to 102.0W. Under these conditions, the amplifier output power remains essentially unchanged (713.8W and 718.0W), while the efficiency increases from 76.7% to 85.5%. In this operating state, although there is a certain amount of second harmonic power output, the device power dissipation is significantly reduced, and the useless power in the circuit is correspondingly reduced, thereby improving energy utilization efficiency.

[0026] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A design method for broadband low-loss harmonic control and power combining networks, characterized in that: An improved impedance matching network is constructed by connecting an additional capacitor in parallel at the output of a traditional T-type impedance matching network. This network enables independent adjustment of the second harmonic impedance, transforming the relatively small fundamental and second harmonic impedances at the transistor drain terminal into an intermediate impedance. Z 1. Achieve impedance matching between the fundamental and harmonic frequencies, and control the relationship between the fundamental and harmonic frequencies; then, utilize a power combining network to adjust the intermediate impedance. Z 1. Complete the port impedance Z The conversion of 2 allows for the synthesis of multiple power streams simultaneously; The improved impedance transformation matching network includes two capacitors. C 3 and C 4 and two inductors L 3 and L 4, of which L One end of 3 is connected to the drain package terminal of the transistor. L The other end of 3 and L 4 and one end C Connect one end of 3. C The other end of 3 is grounded. L The other end of 4 and C Connecting one end of 4 generates an intermediate impedance Z 1, C The other end of 4 is grounded. L 3. C 3 and L 4. Construct a traditional T-type impedance transformation matching network. C 4 represents an additional capacitor.

2. The broadband low-loss harmonic control and power combining network design method according to claim 1, characterized in that: The improved impedance transformation matching network satisfies the following equation: in: R 1+ jX 1 and R 2+ jX 2 represents the fundamental impedance and second harmonic impedance of the transistor drain package, respectively. R 11 + jX 11 and R 22 + jX 22 These are the fundamental impedance and second harmonic impedance of the intermediate impedance, respectively. ω Angular frequency, j The imaginary unit is used; by solving the above equations simultaneously and ensuring that the real and imaginary parts of both sides are equal, the value of the imaginary unit in the improved impedance transformation matching network can be obtained. L 3 and L Inductance value of 4 and C 3 and C The capacitance value is 4.

3. The broadband low-loss harmonic control and power combining network design method according to claim 1, characterized in that: For a dual-path power combining network, a microstrip-based dual-path power combiner is used to convert the input impedance to the output impedance. The dual-path power combiner comprises two microstrip lines. One end of each microstrip line serves as one of the two input ports of the power combiner, connected to its respective input impedance. The other ends of the two microstrip lines are connected in parallel to the output impedance. Each microstrip line is a segment of length... λ / 4 transmission line, λ The characteristic impedance of the microstrip line is the waveguide wavelength. Z C The expression is as follows: in: Z in For input impedance, Z out This is the output impedance.

4. The broadband low-loss harmonic control and power combining network design method according to claim 3, characterized in that: For a four-channel power combining network, a two-stage combining topology is adopted. In the first stage of combining, two dual-channel power combiners are used to combine the intermediate impedances of the four channels. Z 1 converted to two-way intermediate impedance Z mid In the second-stage combining process, a dual-channel power combiner is used to combine the two intermediate impedances. Z mid Convert to port impedance Z 2. The impedance transformation ratios of the two impedance transformations should be as similar as possible and satisfy the following relationship: in: Z C1 The characteristic impedance of the microstrip line in the dual-path power combiner used in the first-stage synthesis is... Z C2 The characteristic impedance of the microstrip line in the dual-path power combiner used for the second-stage synthesis.

5. The broadband low-loss harmonic control and power combining network design method according to claim 4, characterized in that: In the first stage of combining, the four input ports of the two dual-channel power combiners are connected sequentially by resistors.

6. The broadband low-loss harmonic control and power combining network design method according to claim 1, characterized in that: This design method achieves power synthesis while simultaneously matching the fundamental and second harmonic impedances of a broadband, low-loss circuit. By cascading an improved impedance transformation matching network with a power combining network, this method enables power combining.

7. A high-power solid-state microwave power amplifier, characterized in that: This includes a broadband low-loss harmonic control and power combining network implemented using the design method described in any one of claims 1 to 6.

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