Differential impedance transformation network, in-phase power coupler, and power amplifier system

Abstract

This application provides a differential impedance transformation network, an in-phase power coupler, and a power amplifier system, including a differential input port, a differential output port, and N pairs of coupling lines connecting the differential input port and the differential output port, where N ≥ 1. Each pair of coupling lines includes a first coupling line and a second coupling line. The positive input port of the differential input port is connected to the first end of all the first coupling lines, and the negative input port of the differential input port is connected to the second end of all the second coupling lines. The positive output port of the differential output port is connected to the first end of all the second coupling lines, and the negative output port of the differential output port is connected to the second end of all the first coupling lines. This application's solution, by utilizing the odd-mode and even-mode transmission characteristics of the coupling lines, can achieve accurate differential impedance transformation over a wide bandwidth, effectively matching differential signal sources and loads with different impedance levels, and can provide impedance reversal or inversion capabilities to support load modulation.

Description

Technical Field

[0001] This application relates to the field of microwave integrated circuit technology, and in particular to a differential impedance transformation network, an in-phase power coupler, and a power amplifier system. Background Technology

[0002] With the rapid development of wireless communication, radar, and microwave systems, radio frequency power amplifiers often need to achieve high output power and high efficiency simultaneously across wide bandwidths or high frequencies. To meet this requirement, parallel operation of multiple power amplification paths and power combining have become important technical means. Among them, the load modulation architecture represented by the Doherty power amplifier typically relies on a quarter-wavelength impedance inverter to construct the load modulation relationship in the power back-off region. However, the phase and equivalent impedance of the quarter-wavelength transmission line change significantly when deviating from the center frequency, which can easily lead to the load modulation relationship in the actual circuit deviating from the ideal state and the output combining conditions deteriorating. This, in turn, causes a decrease in the efficiency and power performance of the amplifier at the edge of the frequency band, limiting the operating bandwidth of the system.

[0003] To overcome the aforementioned limitations, existing technologies have proposed using multi-segment transmission lines, coupled-line networks, or filter-type structures to achieve broadband impedance transformation and power combining. However, these solutions often face challenges in practical engineering, such as longer electrical lengths, more complex structures, increased layout area, and increased insertion losses. Especially in differential power amplification and in-phase power combining applications, it is necessary to simultaneously consider the phase balance characteristics of the differential ports and the impedance transformation / combining conditions, further increasing the difficulty of network design and implementation. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a differential impedance transformation network, an in-phase power coupler, and a power amplifier system to achieve impedance transformation under differential port conditions and provide impedance reversal or inversion capability.

[0005] To solve one or more of the above-mentioned technical problems, the technical solution adopted in this application is: In a first aspect, this application provides a differential impedance transformation network, including a differential input port, a differential output port, and N pairs of coupling lines connected between the differential input port and the differential output port, wherein N≥1; Each pair of said coupling lines includes a first coupling line and a second coupling line; The positive input port of the differential input port is connected to the first end of all the first coupling lines, and the negative input port of the differential input port is connected to the second end of all the second coupling lines. The positive output port of the differential output port is connected to the first end of all the second coupling lines, and the negative output port of the differential output port is connected to the second end of all the first coupling lines.

[0006] In some specific implementations, the first coupling line in each pair of coupling lines is coupled to the second coupling line at least partially along its length.

[0007] In some specific implementations, the electrical lengths of the first coupling line and the second coupling line are no greater than 45°.

[0008] In some specific embodiments, the electrical lengths of the first coupling line and the second coupling line are 15° to 45°.

[0009] In some specific implementations, the electrical lengths of the first coupling line and the second coupling line are different.

[0010] In some specific implementations, the impedance of the differential input port is inversely proportional to the impedance of the differential output port.

[0011] In some specific implementations, the impedances of the differential input port and the differential output port are determined based on the odd-mode impedance, even-mode impedance, and electrical length of the coupled line pair.

[0012] Secondly, this application also provides an in-phase power coupler, including a pair of first differential signal ports, M pairs of second differential signal ports, and M differential signal paths connected between the first differential signal ports and the M pairs of second differential signal ports, wherein M≥2; Each of the differential signal paths includes a differential impedance transformation network as described in any of the first aspects; The positive terminal of the first differential signal port is connected to the positive input terminal of the differential input terminal of all the differential impedance transformation networks, and the negative terminal of the first differential signal port is connected to the negative input terminal of the differential input terminal of all the differential impedance transformation networks. The positive and negative ports of each of the second differential signal ports are respectively connected to the positive and negative output ports of the differential output ports of one of the differential impedance transformation networks.

[0013] In some specific implementations, the in-phase power coupler is a power divider, with the first differential signal port serving as the differential signal input port and the second differential signal port serving as the differential signal output port. Alternatively, the in-phase power coupler can be a combiner, with the first differential signal port serving as the differential signal output port and the second differential signal port serving as the differential signal input port.

[0014] Thirdly, this application also provides a power amplifier system, the system including an input port, an output port, and a space disposed between the input port and the output port: Multiple power amplification paths are connected to the input port, including at least one main power amplification path and at least one peak power amplification path, for amplifying one input signal received from the input port respectively; wherein each power amplification path includes a power amplification unit and a differential impedance transformation network as described in any of the first aspects; A distribution network, connected between the input port and the multiple power amplification paths, is used to distribute the power of one input signal input from the input port and output multiple signals. A power combining network is connected between the multiple power amplification paths and the output port to combine the amplified signals output from all the power amplification paths to obtain a combined output signal.

[0015] In some specific implementations, the distribution network employs a power divider implemented with an in-phase power coupler as described in any of the second aspects; Alternatively, the combining network may employ a combiner implemented using an in-phase power coupler as described in any of the second aspects.

[0016] The proposed solution constructs a high-performance balanced-to-balanced four-port converter structure by cross-connecting N pairs of coupled wires (N≥1) between the differential input and differential output ports. In differential mode, this structure utilizes the odd-mode and even-mode transmission characteristics of the coupled wires to achieve precise differential impedance transformation over a wide bandwidth, effectively matching differential signal sources and loads with different impedance levels. Furthermore, through the coordinated design of the cross-connection topology and the phase of the coupled segments, the network exhibits significant impedance reversal or inversion characteristics near the center frequency; that is, the differential impedance at the network input and the load impedance at the output satisfy an inverse relationship. This characteristic allows it to be embedded as an ideal impedance inverter in Doherty power amplifiers and out-of-phase equal-load modulation architectures, achieving dynamic and efficient modulation of the equivalent load impedance of the main amplifier and peak amplifier, thereby significantly improving the overall system efficiency and linearity in the power back-off range. In addition, by adjusting the number of coupled wires, odd-mode impedance, and electrical length, bandwidth, size, and conversion ratio can be flexibly balanced to meet the compact design requirements of modern wireless communication systems for wideband, high-efficiency power amplification.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the differential impedance transformation network provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the simulation results of Example 1 of the differential impedance transformation network provided in Embodiment 1 of this application; Figure 3 This is a schematic diagram of the simulation results of Example 2 of the differential impedance transformation network provided in Embodiment 1 of this application; Figure 4 This is a schematic diagram of the simulation results of Example 3 of the differential impedance transformation network provided in Embodiment 1 of this application; Figure 5 This is a schematic diagram of the simulation results of Example 4 of the differential impedance transformation network provided in Embodiment 1 of this application; Figure 6 This is a schematic diagram of the simulation results of Example 5 of the differential impedance transformation network provided in Embodiment 1 of this application; Figure 7 This is a schematic diagram of the differential impedance transformation network provided in Embodiment 2 of this application; Figure 8 This is a schematic diagram of the simulation results of Example 6 of the differential impedance transformation network provided in Embodiment 2 of this application; Figure 9 This is a schematic diagram of the differential impedance transformation network provided in Embodiment 3 of this application; Figure 10 This is a schematic diagram of the in-phase power coupler provided in Embodiment 4 of this application; Figure 11 This is a schematic diagram of the power amplifier system provided in Embodiment 5 of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] As described in the background section, existing solutions for broadband impedance transformation and power combining using multi-segment transmission lines, coupled-line networks, or filter-type structures often face challenges in practical engineering, such as longer electrical lengths, more complex structures, increased layout area, and increased insertion losses. Especially in differential power amplification and in-phase power combining applications, it is necessary to simultaneously consider the phase balance characteristics of the differential ports and the impedance transformation / combining conditions, further increasing the difficulty of network design and implementation.

[0022] To address one or more of the aforementioned problems, this application proposes a differential impedance transformation network, an in-phase power coupler, and a power amplifier system. By employing N pairs of coupled lines (N≥1) cross-connected between the differential input port and the differential output port, a high-performance balanced-to-balanced four-port converter structure is constructed. In differential operating mode, this structure utilizes the odd-mode and even-mode transmission characteristics of the coupled lines to achieve accurate differential impedance transformation over a wide bandwidth, effectively matching differential signal sources and loads with different impedance levels. Furthermore, through the coordinated design of the cross-connection topology and the phase of the coupled segments, this network exhibits significant impedance reversal or inversion characteristics near the center frequency; that is, the differential impedance at the network input and the load impedance at the output satisfy an inverse relationship.

[0023] The present application will be described in detail below through specific embodiments.

[0024] Example 1 Figure 1 The following are schematic diagrams of the differential impedance transformation network provided in some embodiments of this application, with reference to... Figure 1 As shown, in the differential impedance transformation network provided in this embodiment, the number N is selected as 1. The differential impedance transformation network includes a differential input port 110, a differential output port 120, and a pair of coupling lines 130 connecting the differential input port 110 and the differential output port 120. The coupling line pair 130 includes a first coupling line 131 and a second coupling line 132. The differential input port 110 includes a positive input port 111 and a negative input port 112, and the differential output port 120 includes a positive output port 121 and a negative output port 122.

[0025] It should be noted that in some embodiments, the port structure of the differential impedance transformation network follows the core principle of differential signal transmission to ensure signal integrity and noise suppression capability. Specifically, in the working state, the two signals in each pair of differential ports maintain a 180° phase difference, that is, the signal phase difference between the positive input port 111 and the negative input port 112 is 180°, and the signal phase difference between the positive output port 121 and the negative output port 122 is 180°. During operation, a pair of standard differential signals with equal amplitude and opposite phase (i.e., the phase difference between them is constant at 180°) are applied to the positive input port 111 and the negative input port 112 of the differential input port 110. After impedance transformation and signal conditioning by the internal coupled line pair, the signals output from the positive output port 121 and the negative output port 122 of the differential output port 120 also maintain the ideal differential characteristics of equal amplitude and opposite phase, and the phase difference between them is also strictly maintained at 180°. This ensures that the transformed signal can be correctly received and processed by the subsequent differential circuit.

[0026] Further reference Figure 1 As shown, in some embodiments, the positive input port 111 is connected to the first end 1311 of the first coupling line 131, and the negative input port 112 is connected to the second end 1322 of the second coupling line 132; the positive output port 121 is connected to the first end 1321 of the second coupling line 132, and the negative output port 122 is connected to the second end 1312 of the first coupling line 131. By using coupling pairs to cross-connect between the differential input ports and the differential output ports, a high-performance balanced-to-balanced four-port converter structure is constructed. In differential operating mode, this structure utilizes the odd-mode and even-mode transmission characteristics of the coupling pairs to achieve accurate differential impedance transformation over a wide bandwidth, effectively matching differential signal sources and loads with different impedance levels. Furthermore, through the coordinated design of the cross-connection topology and the phase of the coupling segments, this network exhibits significant impedance reversal or inversion characteristics near the center frequency.

[0027] Further reference Figure 1As shown, in some specific embodiments, the first coupling line 131 and the second coupling line 132 are configured to be arranged in parallel and closely adjacent spaces, thereby ensuring electromagnetic coupling (i.e., at least partial length coupling) along at least a portion of the transmission path. This coupling region is crucial for realizing core functions such as differential impedance transformation and common-mode rejection. Specifically, within this coupling length, the electromagnetic fields between the first coupling line 131 and the second coupling line 132 overlap, forming a tight capacitive and inductive coupling. When a differential signal passes through, this coupling effect has two important functions: on the one hand, it can change the effective characteristic impedance of the signal transmission, thereby assisting in achieving the required impedance transformation; on the other hand, it can enhance the suppression of common-mode noise, because common-mode signals will suffer greater losses or cancel each other out in the coupled structure. By precisely controlling physical parameters such as the length of the coupling section, the spacing between lines, and the parallelism, the coupling strength and frequency response can be flexibly adjusted, enabling the impedance transformation network to achieve optimal differential signal transmission performance and matching effect within the target frequency band. This "at least partially coupled" design ensures the realization of the core coupling effect and provides flexibility in circuit layout, allowing for optimization and adjustment based on overall size or performance trade-offs.

[0028] In some embodiments, the electrical lengths of the first coupling line 131 and the second coupling line 132 are configured to be no greater than 45° to ensure that the differential impedance transformation network can maintain stable performance over a wide frequency range and optimize its function as an impedance matching and signal transformation device. Specifically, on the one hand, shorter electrical lengths result in a flatter frequency response and more linear phase changes for the coupling line pair, thereby widening the effective operating bandwidth of the impedance transformation network and facilitating good matching characteristics over a wide bandwidth. On the other hand, electrical length directly corresponds to physical size; controlling the electrical length to a smaller value is beneficial for achieving a compact and integrated design of the entire network, which is particularly important for high-frequency, high-density integrated circuit packaging and PCB layout. Furthermore, with shorter electrical lengths, the mutual coupling effect between the coupling lines can be modeled and controlled more accurately, avoiding uncertainties in distributed parameters or parasitic effects introduced by excessively long transmission lines, thereby improving design consistency and performance predictability.

[0029] In some embodiments, the electrical lengths of the first coupling line 131 and the second coupling line 132 are further limited to the range of 15° to 45°. On the one hand, this ensures that the coupling lines have sufficient length to establish effective electromagnetic coupling, thereby providing the necessary impedance transformation capability and common-mode rejection effect; on the other hand, it maintains the advantages of wide bandwidth, small size, and controllability, while avoiding excessive frequency selectivity, narrowed bandwidth, or increased phase distortion due to excessive electrical length. In summary, within this range (15° to 45°), the optimal electrical length can be flexibly selected according to the specific application scenario (such as target impedance transformation ratio, center frequency, bandwidth requirements, etc.), achieving an optimized trade-off between performance and size.

[0030] In some embodiments, the first coupling line 131 and the second coupling line 132 are configured to have the same electrical length. It is understood that when a pair of ideal differential signals are input, the signals travel along paths of exactly the same electrical length, experiencing identical phase delays and amplitude responses. This ensures that the signals maintain strict phase inversion (180° phase difference) and equal amplitude at the output port, thus preserving the integrity of the differential signal and minimizing common-mode components caused by internal path imbalances. Secondly, for common-mode noise or interference, the two perfectly symmetrical coupling line paths provide a consistent transmission environment. With the subsequent port cross-connection structure, these common-mode signals can achieve effective phase cancellation at the output, greatly improving the network's common-mode rejection capability and enhancing the system's anti-interference ability. Furthermore, the symmetrical structure greatly simplifies the electromagnetic analysis and modeling of the circuit. Designers can focus their analysis on the characteristics of individual paths (such as characteristic impedance and coupling coefficient), while the differential performance of the entire network can be directly derived from the symmetry. This reduces design complexity and improves design predictability and manufacturing consistency. Furthermore, given the symmetry of the electrical length, the impedance characteristics of the network for differential-mode signals are deterministic and easily adjustable. By precisely designing this same electrical length value (e.g., combined with a preferred design within the range of 15° to 45°), excellent and flat differential-mode impedance matching can be achieved within the target frequency band, meeting the requirements of broadband applications.

[0031] In other embodiments, the first coupling line 131 and the second coupling line 132 are configured with different electrical lengths. This differentiated electrical length configuration allows for independent control of the two impedance paths, significantly widening the network's effective operating bandwidth while meeting complex impedance transformation requirements. Specifically, on the positive and negative paths of the differential signal (primarily dominated by the first and second coupling lines, respectively), different electrical lengths mean that the phase delay and impedance transformation process experienced by the signal can be independently optimized. This allows the network to precisely match the potentially asymmetrical or complex impedance characteristics of the source and load ends simultaneously, achieving a precise matching target that is difficult to achieve with traditional symmetrical structures. Secondly, by adjusting the difference in electrical length between the two paths, the network's scattering parameters (especially differential-mode insertion loss Sdd21 and return loss Sdd11) can be "shaped" over a wider frequency range. For example, the frequency response differences of paths with different electrical lengths can be used to achieve phase compensation or broaden the response peak, thereby synthesizing a generally flatter, wider-bandwidth transmission response. This is crucial for the broadband and even ultra-wideband operation required by modern high-speed communication systems. Furthermore, although the input and output ports maintain a strict 180° phase difference, the difference in electrical length of the internal paths can serve as a controlled asymmetry to optimize the common-mode rejection ratio (CMRR) or amplitude balance at specific frequencies or bands. By actively designing the asymmetry, it may be possible to achieve better overall balance performance than a fully symmetrical structure.

[0032] In some embodiments, the impedance of the differential input port 110 is inversely proportional to the impedance of the differential output port 120. Specifically, since the differential impedance transformation network operates in a differential manner, i.e., the positive input port 111 and the negative input port 112 are 180° differential inputs, and the positive output port 121 and the negative output port 122 are 180° differential outputs, and the structure is symmetrical with cross-connected ports, under differential excitation, the two branches (from the positive input port 111 to the negative output port 122, and from the negative input port 112 to the positive output port 121) form an equal-amplitude and opposite-current relationship at the input / output terminals. This causes the terms related to "direct transmission at this terminal" in the equivalent two-port circuit to cancel each other out near the center frequency, while the coupling transmission between ports plays a dominant role. Therefore, this structure can be approximated as an impedance inverter under differential equivalence, and its impedance transformation satisfies: That is, when the load is high impedance, the input is low impedance, and when the load is low impedance, the input is high impedance, thus realizing impedance reversal / inversion.

[0033] in, The impedance of differential input port 110, This is the impedance (i.e., load impedance) of the differential output port 120. The inverting constant can be determined from the coupled line even-mode impedance. Odd-mode impedance and electrical length Confirmed, indicated as: in, The electrical length at the center frequency (different values ​​can be used for each path) However, all of them meet the design constraint of no more than 45°.

[0034] It should be noted that, in this embodiment, the impedance of the differential input port 110 and the impedance of the differential output port 120 do not refer to fixed terminating devices within the network itself, but rather to the impedance of the differential load connected to the differential output port. Under these conditions, the equivalent differential input impedance viewed from the differential input port With external differential load impedance It satisfies the impedance inversion / flipping relationship.

[0035] In some embodiments, external differential load This can be provided by the equivalent impedance of the device ports in the power amplifier system. For example, in the Doherty power amplifier application scenario, when the peak-path power device is in the off state, its drain current is approximately zero, and its drain-source port can be equivalent to a high-impedance state in the operating frequency band (approximately an open circuit or a high-impedance state dominated by the device's output capacitance), thus forming the external differential load. The high-impedance condition is used to verify the impedance reversal relationship described above. If necessary, the high-impedance state can also be approximated in the simulation using a large resistance (such as 10kΩ), and the results obtained are consistent with the equivalent high-impedance condition of the turn-off device.

[0036] It is understandable that odd-mode impedance Even-mode impedance refers to the impedance presented by a transmission line when a signal of the same polarity (common-mode signal) is applied to both coupled lines in the same coupled line pair; even-mode impedance. The impedance of a transmission line is the electrical length when signals of opposite polarity (differential signals) are applied to the two coupled lines of the same coupled line pair. The phase delay refers to the time delay of a signal as it propagates on a transmission line, usually expressed in terms of angle (e.g., 90°) or wavelength ratio (e.g., λ / 4).

[0037] The following examples illustrate impedance reversal or inverting capability. Under matched verification conditions, let... and Under impedance reversal verification conditions, let , (Approximately open-circuit high-impedance state), and read the equivalent impedance at the input terminal at the center frequency (10 GHz in the example) (derived from the reflection coefficient).

[0038] Example 1: Let Electrical length approximately 15° Coupled line parameters: Even-mode impedance Odd-mode impedance Electrical length Matching verification: The equivalent impedance at the input is approximately That is, a 50Ω match.

[0039] Impedance reversal verification (load in high impedance state): the equivalent impedance at the input is approximately The real part decreases significantly, reflecting the switching characteristic of a high-impedance load being inverted into a low-impedance input, such as... Figure 2 As shown.

[0040] Example 2: Let Electrical length approximately 30° Coupled line parameters: Even-mode impedance Odd-mode impedance Electrical length Matching verification: The equivalent impedance at the input is approximately Impedance reversal verification: The equivalent impedance at the input is approximately The real part still maintains a low resistance level, indicating that it still has impedance reversal capability at this electrical length, such as Figure 3 As shown.

[0041] Example 3: Let Electrical length approximately 45° Coupled line parameters: Even-mode impedance Odd-mode impedance Electrical length Matching verification: The equivalent impedance at the input is approximately Impedance reversal verification: The equivalent impedance at the input is approximately The real part maintains low resistance, demonstrating inverter characteristics, such as Figure 4 As shown.

[0042] Example 4: Let Electrical length approximately 45° Coupled line parameters: Even-mode impedance Odd-mode impedance Electrical length Matching verification: The equivalent impedance at the input is approximately Impedance reversal verification: The equivalent impedance at the input is approximately This enables the switching from a high-impedance load to a low-impedance input, such as... Figure 5 As shown.

[0043] In summary, the four examples above with different electrical lengths and different system impedances all show that when the load is in a high-impedance state, the equivalent impedance at the input terminal transforms into a low-impedance order at the target frequency (the real part is significantly smaller than 1). ),and The inversion law is consistent with that of the present application, thus verifying that the present application has impedance reversal / inversion capability.

[0044] In some embodiments, the impedances of the differential input port 110 and the differential output port 120 are determined based on the odd-mode impedances of the coupled line pair (including the first coupled line 131 and the second coupled line 132). Even-mode impedance and electrical length Confirmed. It is understood that the embodiments of this application adjust the odd-mode impedance of the first coupling line 131 and the second coupling line 132. Even-mode impedance and electrical length This enables various impedance matching methods for differential impedance transformation networks. In practice, the odd-mode impedance is altered by adjusting the distance and geometry between coupled line pairs. Odd-mode impedance Adjusting the impedance is crucial for differential signal transmission because it directly affects the transmission characteristics. Similarly, adjusting the distance and geometry between coupled wire pairs can change the even-mode impedance. Even-mode impedance The adjustment of electrical length is crucial for common-mode signal transmission because it directly affects the transmission characteristics of common-mode signals. The adjustment can be achieved by changing the actual physical length of the coupling line or by changing the signal propagation speed. Electrical length The adjustment of the phase has a significant impact on the phase and transmission delay of the signal.

[0045] It should be noted that the embodiments of this application do not impose specific limitations on the impedance matching of the differential impedance transformation network. Without departing from the inventive concept of this application, the impedance matching can be set according to actual product requirements.

[0046] In some embodiments, the odd-mode impedance of the first coupling line 131 and the second coupling line 132 It can range from 3.3Ω to 21Ω.

[0047] In some embodiments, the even-mode impedance of the first coupling line 131 and the second coupling line 132 It can be 60Ω to 190Ω.

[0048] It should be noted that the above-mentioned odd-mode impedance Even-mode impedance and electrical length The range of values ​​for is merely an example range of feasible parameters shown in specific embodiments of the present invention to achieve a specific impedance transformation ratio (such as realizing a high impedance switching function). This range is not a fixed limitation on the present invention, but rather reflects the universality and flexibility of its design method.

[0049] Example 5: Under a 50Ω path, the first coupling line 131 and the second coupling line 132 correspond to... =60Ω, =10Ω, =45°, and the simulation results are as follows Figure 6 As shown.

[0050] Example 2 Figure 7 This is a schematic diagram of the differential impedance transformation network provided in Embodiment 2 of this application, referring to... Figure 7 As shown, the difference from Embodiment 1 is that in the differential impedance transformation network provided in this application embodiment, the number N is selected as 2. This differential impedance transformation network includes a differential input port 210, a differential output port 220, and two pairs of coupling lines 230a and 230b connecting the differential input port 210 and the differential output port 220. Coupler pair 230a includes a first coupling line 231a and a second coupling line 232a, and coupling line pair 230b includes a first coupling line 231b and a second coupling line 232b. The differential input port 210 includes a positive input port 211 and a negative input port 212, and the differential output port 220 includes a positive output port 221 and a negative output port 222.

[0051] In this embodiment, the port structure of the differential impedance transformation network also follows the core principle of differential signal transmission to ensure signal integrity and noise suppression capability. Specifically, in operation, the two signals in each pair of differential ports maintain a 180° phase difference; that is, the signal phase difference between the positive input port 211 and the negative input port 212 is 180°, and the signal phase difference between the positive output port 221 and the negative output port 222 is 180°. During operation, a pair of standard differential signals with equal amplitude and opposite phase (i.e., the phase difference between them is constant at 180°) are applied to the positive input port 211 and the negative input port 212 of the differential input port 210. After impedance transformation and signal conditioning by the internal coupled line pairs, the signals output from the positive output port 221 and the negative output port 222 of the differential output port 220 also maintain the ideal differential characteristics of equal amplitude and opposite phase, and the phase difference between them is also strictly maintained at 180°. This ensures that the transformed signal can be correctly received and processed by the subsequent differential circuit.

[0052] Further reference Figure 7 As shown, in some embodiments, the positive input port 211 is connected to the first end 2311a of the first coupling line 231a and the first end 2311b of the first coupling line 231b; the negative input port 212 is connected to the second end 2322a of the second coupling line 232a and the second end 2322b of the second coupling line 232b; the positive output port 221 is connected to the first end 2321a of the second coupling line 232a and the first end 2321b of the second coupling line 232b; and the negative output port 222 is connected to the second end 2312a of the first coupling line 231a and the second end 2312b of the first coupling line 231b. By using coupling pairs to cross-connect between the differential input port and the differential output port, a high-performance balanced-to-balanced four-port converter structure is constructed. In differential operating mode, this structure utilizes the odd-mode and even-mode transmission characteristics of the coupling pairs to achieve accurate differential impedance transformation over a wide bandwidth, effectively matching differential signal sources and loads with different impedance levels. Furthermore, through the coordinated design of cross-connection topology and coupled segment phase, the network exhibits significant impedance reversal or inverting characteristics near the center frequency.

[0053] In this embodiment, the contents that are the same as or similar to those in Embodiment 1 above can be referred to the above description, and will not be repeated here.

[0054] Example 6: Under a 50Ω path, the first coupling lines 131a and 131b, and the second coupling lines 132a and 132b correspond to... =120Ω, =20Ω, =45°, and the simulation results are as follows Figure 8 As shown.

[0055] Reference Figure 6 and Figure 8 As shown, both embodiments can achieve the same effect.

[0056] Example 3 Figure 9 This is a schematic diagram of the differential impedance transformation network provided in Embodiment 3 of this application, with reference to... Figure 9 As shown, the difference from Embodiment 1 is that the differential impedance transformation network provided in this application has a larger number of coupling line pairs, denoted by N, where N≥2 and is a positive integer. This differential impedance transformation network includes a differential input port 310, a differential output port 320, and N pairs of coupling line pairs 3301-330N connecting the differential input port 310 and the differential output port 320. Each pair of coupling line pairs includes a first coupling line and a second coupling line. For example, the i-th differential coupling line pair 330i includes a first coupling line 330ia and a second coupling line 330ib, where 1≤i≤N and i is a positive integer. That is, the first differential coupling line pair 3301 includes a first coupling line 3301a and a second coupling line 3301b, the second differential coupling line pair 3302 includes a first coupling line 3302a and a second coupling line 3302b, and so on, with the Nth differential coupling line pair 330N including a first coupling line 330Na and a second coupling line 330Nb. The differential input port 310 includes a positive input port 311 and a negative input port 312, and the differential output port 320 includes a positive output port 321 and a negative output port 322.

[0057] In this embodiment, the port structure of the differential impedance transformation network also follows the core principle of differential signal transmission to ensure signal integrity and noise suppression capability. Specifically, in operation, the two signals in each pair of differential ports maintain a 180° phase difference; that is, the signal phase difference between the positive input port 311 and the negative input port 312 is 180°, and the signal phase difference between the positive output port 321 and the negative output port 322 is 180°. During operation, a pair of standard differential signals with equal amplitude and opposite phase (i.e., the phase difference between them is constant at 180°) are applied to the positive input port 311 and the negative input port 312 of the differential input port 310. After impedance transformation and signal conditioning by the internal coupled line pairs, the signals output from the positive output port 321 and the negative output port 322 of the differential output port 320 also maintain the ideal differential characteristics of equal amplitude and opposite phase, and the phase difference between them is also strictly maintained at 180°. This ensures that the transformed signal can be correctly received and processed by the subsequent differential circuit.

[0058] Further reference Figure 9As shown, in some embodiments, the positive input port 311 is connected to the first end of all first coupling lines, and the negative input port 312 is connected to the second end of all second coupling lines; the positive output port 321 is connected to the first end of all second coupling lines, and the negative output port 322 is connected to the second end of all first coupling lines. By using coupling pairs cross-connected between the differential input ports and differential output ports, a high-performance balanced-to-balanced four-port converter structure is constructed. In differential operating mode, this structure utilizes the odd-mode and even-mode transmission characteristics of the coupling pairs to achieve accurate differential impedance transformation over a wide bandwidth, effectively matching differential signal sources and loads with different impedance levels. Furthermore, through the coordinated design of the cross-connection topology and the phase of the coupling segments, this network exhibits significant impedance reversal or inversion characteristics near the center frequency.

[0059] In this embodiment, the contents that are the same as or similar to those in Embodiment 1 or 2 described above can be referred to the above description, and will not be repeated here.

[0060] Example 4 Corresponding to embodiments one to three above, this application also provides an in-phase power coupler, which generally includes a pair of first differential signal ports, M pairs of second differential signal ports, and M differential signal paths connected between the first differential signal ports and the M pairs of second differential signal ports, where M ≥ 2. Each differential signal path includes a differential impedance transformation network as described in any one of embodiments one to three. The positive port of the first differential signal port is connected to the positive input port of the differential input port of all differential impedance transformation networks, and the negative port of the first differential signal port is connected to the negative input port of the differential input port of all differential impedance transformation networks. The positive and negative ports of each second differential signal port are respectively connected to the positive and negative output ports of the differential output ports of one of the differential impedance transformation networks. In this embodiment, content that is the same as or similar to embodiments one to three above can be referred to the above description, and will not be repeated here.

[0061] The following describes the in-phase power coupler provided in this application in detail, taking the example of M being selected as 2 and each differential signal path including a differential impedance transformation network as described in any one of Embodiment 1.

[0062] Reference Figure 10 As shown, the in-phase power coupler provided in this application embodiment includes a pair of first differential signal ports 401, two pairs of second differential signal ports 4021 and 4022, and two differential signal paths connected between the first differential signal ports 401 and the two pairs of second differential signal ports 4021 and 4022. Each differential signal path includes a differential impedance transformation network as described in any of the embodiments.

[0063] Further reference Figure 10 As shown, the first differential signal port 401 includes a positive port 401a and a negative port 401b, the second differential signal port 4021 includes a positive port 4021a and a negative port 4021b, and the second differential signal port 4022 includes a positive port 4022a and a negative port 4022b. The positive port 401a of the first differential signal port 401 is connected to the positive input port of the differential input port of all differential impedance transformation networks, and the negative port 401b of the first differential signal port 401 is connected to the negative input port of the differential input port of all differential impedance transformation networks. The positive port 4021a and the negative port 4021b of the second differential signal port 4021 are respectively connected to the positive output port and the negative output port of the differential output port of one of the differential impedance transformation networks. The positive port 4022a and the negative port 4022b of the second differential signal port 4022 are respectively connected to the positive output port and the negative output port of the differential output port of another differential impedance transformation network.

[0064] The in-phase power coupler provided in this application embodiment is constructed based on the aforementioned differential impedance transformation network. Its architecture possesses bidirectional reciprocal operation capabilities for power combining and power distribution, a characteristic that brings significant technical advantages and design convenience. Structurally, this in-phase power coupler consists of a first differential signal port and M second differential signal ports connected through parallel differential signal paths. Each path contains a differential impedance transformation network with consistent performance. This topology is physically completely symmetrical and reversible. This architecture fully utilizes the port characteristics of the basic unit—the differential impedance transformation network. The input and output ports of this differential impedance transformation network are themselves defined as strictly differential pairs (180° phase difference). In this coupler, these differential ports are "split" and connected in a specific manner: the positive ports of all differential input terminals are interconnected and led out as the positive terminal of the first differential signal port, and all negative ports are interconnected and led out as the negative terminal of the first differential signal port. This connection method ensures that, viewed from the first differential signal port, the positive and negative terminals naturally inherit and maintain the required 180° phase difference driving condition for each internal differential port pair. Therefore, although the external ports of the entire coupler appear as single-ended to ground, its internal driving mechanism and signal path are entirely based on a strict differential foundation. This not only guarantees excellent common-mode rejection capability transmitted from the basic unit to the entire coupler, but also allows the coupler to be seamlessly integrated into modern RF and high-speed systems dominated by differential signals, without the need for additional balanced-to-unbalanced conversion, simplifying system design and maintaining signal integrity.

[0065] It should be noted that the in-phase power coupler provided in this application embodiment can be used to implement both a power divider and a combiner. It is understood that when the above-mentioned in-phase power coupler is a power divider, the first differential signal port 401 is used as the differential signal input port, and the two second differential signal ports 4021 and 4022 are used as differential signal output ports; when the above-mentioned in-phase power coupler is a combiner, the first differential signal port 401 is used as the differential signal output port, and the two second differential signal ports 4021 and 4022 are used as differential signal input ports, which will not be elaborated further here.

[0066] Example 5 This application also provides a power amplifier system, as shown in the reference. Figure 11 As shown, it generally includes an input port RFInput, an output port RFOutput, and multiple power amplification paths, a distribution network 1000, and a combining network 2000 disposed between the input port RFInput and the output port RFOutput. Each of the multiple power amplification paths is connected to the input port RFInput, and includes at least one main power amplification path 3100 and at least one peak power amplification path 3200, used to amplify one input signal received from the input port RFInput. Each power amplification path includes a power amplification unit 3300 and a differential impedance transformation network 3400 as described in any one of embodiments one to three. The distribution network 1000 is connected between the input port RFInput and the multiple power amplification paths, used to distribute the power of one input signal input to the input port RFInput, splitting it into multiple output signals. The combining network 2000 is connected between the multiple power amplification paths and the output port RFOutput, used to combine the amplified signals output from all the power amplification paths to obtain a combined output signal. In this embodiment, the contents that are the same as or similar to those in embodiments one to three above can be referred to the above description, and will not be repeated here.

[0067] The power amplifier system provided in this application embodiment achieves a breakthrough improvement over the traditional Doherty amplifier architecture by integrating a differential impedance transformation network into its power amplification path. Its core technological advantage lies in its ability to achieve broadband load modulation without relying on a fixed quarter electrical length, thereby significantly expanding the system's operating bandwidth and application scenarios. Specifically, at the output of each amplification path (including the main power amplifier and the peak power amplifier), the aforementioned differential impedance transformation network replaces the impedance inverter, which is indispensable in the traditional Doherty architecture and is based on a specific λ / 4 electrical length. It should be noted that the phase delay and impedance transformation characteristics of the traditional λ / 4 impedance inverter are strongly frequency-dependent, and its ideal performance is only effective within a very narrow bandwidth near the center frequency. This constitutes an inherent broadband bottleneck for the Doherty amplifier. The differential impedance transformation network in this system, through the odd-mode / even-mode impedance of its coupling pair (… The design, in conjunction with a short electrical length of no more than 45°, enables the required impedance reversal and phase compensation functions over a frequency range much wider than λ / 4 lines. This significantly extends the effective operating bandwidth of the entire Doherty load modulation network.

[0068] Understandably, the core of broadband Doherty's operation is that, at different power levels and frequencies, the peak power amplifier's conduction can effectively modulate the load impedance seen by the main power amplifier, bringing it close to its optimal value in both the saturation and back-off regions. The differential impedance transformation network in this scheme has an impedance transformation relationship derived from... and The frequency response of a network is determined by a combination of parameters, not just a single physical length. By precisely designing these parameters, the network's frequency response can be "shaped" to approximately meet certain requirements over a wide bandwidth. The inverse relationship ensures that the load modulation effect is effective over a wide bandwidth, maintaining the system's high efficiency. Furthermore, no longer constrained by a precise λ / 4 physical length, designers can optimize within a more compact size constraint. and This allows for a trade-off between bandwidth, efficiency, and conversion ratio. The flexibility of this design enables the power amplifier system to better adapt to the broadband, multi-band, and even carrier aggregation scenarios required by modern communication standards such as 5G NR.

[0069] In some embodiments, the distribution network can directly employ a power divider implemented using an in-phase power coupler as described in any of Embodiment 4, and / or the combining network can directly employ a combiner implemented using the same in-phase power coupler. Due to the bidirectional reciprocal operation of the in-phase power coupler, when used as a distribution network, it can distribute the input signal with low loss and high isolation in phase; when used as a combining network, it can efficiently and with low distortion combine the amplified signals in phase. This symmetry ensures that the signal undergoes completely complementary path responses during the distribution and combining stages, which is beneficial for optimizing the overall system gain flatness and phase consistency. Furthermore, since the internal construction of this in-phase power coupler is based on a differential impedance transformation network, although its external ports are single-ended, its internal operation is essentially differential. This has natural compatibility with the output / input interfaces in the power amplification path, which also contain differential impedance transformation networks. This fully differential signal chain design maximizes signal balance throughout the entire process from distribution and amplification to synthesis, effectively suppressing common-mode noise and ground bounce interference, and improving the linearity and stability of the system in complex electromagnetic environments.

[0070] Furthermore, using the same core components to perform both distribution and combining functions greatly simplifies bill of materials and supply chain management. More importantly, this in-phase power coupler, due to its short-wire coupling design, is typically smaller in physical size than traditional multi-stage λ / 4-wire power dividers / combiners. This facilitates the compact and highly integrated design of the entire power amplifier system, particularly multi-channel Doherty or balanced amplifier architectures.

[0071] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0072] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0073] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0074] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A differential impedance transformation network, characterized in that, It includes a differential input port, a differential output port, and N pairs of coupling lines connected between the differential input port and the differential output port, wherein N≥1; Each pair of said coupling lines includes a first coupling line and a second coupling line; The positive input port of the differential input port is connected to the first end of all the first coupling lines, and the negative input port of the differential input port is connected to the second end of all the second coupling lines. The positive output port of the differential output port is connected to the first end of all the second coupling lines, and the negative output port of the differential output port is connected to the second end of all the first coupling lines.

2. The differential impedance transformation network as described in claim 1, characterized in that, In each pair of said coupling lines, the first coupling line is coupled to the second coupling line at least a portion of its length.

3. The differential impedance transformation network as described in claim 2, characterized in that, The electrical lengths of the first coupling line and the second coupling line are no greater than 45°.

4. The differential impedance transformation network as described in claim 3, characterized in that, The electrical lengths of the first coupling line and the second coupling line are 15° to 45°.

5. The differential impedance transformation network as described in any one of claims 1 to 4, characterized in that, The first coupling line and the second coupling line have different electrical lengths.

6. The differential impedance transformation network as described in any one of claims 1 to 4, characterized in that, The impedance of the differential input port is inversely proportional to the impedance of the differential output port.

7. The differential impedance transformation network as described in any one of claims 1 to 4, characterized in that, The impedances of the differential input port and the differential output port are determined based on the odd-mode impedance, even-mode impedance, and electrical length of the coupled line pair.

8. A non-inverting power coupler, characterized in that, It includes a pair of first differential signal ports, M pairs of second differential signal ports, and M differential signal paths connected between the first differential signal ports and the M pairs of second differential signal ports, wherein M ≥ 2; Each of the differential signal paths includes a differential impedance transformation network as described in any one of claims 1 to 7; The positive terminal of the first differential signal port is connected to the positive input terminal of the differential input terminal of all the differential impedance transformation networks, and the negative terminal of the first differential signal port is connected to the negative input terminal of the differential input terminal of all the differential impedance transformation networks. The positive and negative ports of each of the second differential signal ports are respectively connected to the positive and negative output ports of the differential output ports of one of the differential impedance transformation networks.

9. The in-phase power coupler according to claim 8, characterized in that, The in-phase power coupler is a power divider, with the first differential signal port serving as the differential signal input port and the second differential signal port serving as the differential signal output port. Alternatively, the in-phase power coupler can be a combiner, with the first differential signal port serving as the differential signal output port and the second differential signal port serving as the differential signal input port.

10. A power amplifier system, characterized in that, The system includes an input port, an output port, and a space disposed between the input port and the output port. Multiple power amplification paths are connected to the input port, including at least one main power amplification path and at least one peak power amplification path, for amplifying one input signal received from the input port respectively; wherein each power amplification path includes a power amplification unit and a differential impedance transformation network as described in any one of claims 1 to 7; A distribution network, connected between the input port and the multiple power amplification paths, is used to distribute the power of one input signal input from the input port and output multiple signals. A power combining network is connected between the multiple power amplification paths and the output port to combine the amplified signals output from all the power amplification paths to obtain a combined output signal.

11. The power amplifier system according to claim 10, characterized in that, The distribution network employs a power divider implemented using an in-phase power coupler as described in any one of claims 8 to 9; Alternatively, the combining network may employ a combiner implemented using an in-phase power coupler as described in any one of claims 8 to 9.

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