Dual-band impedance transformer and dual-band power amplifier

Abstract

The application provides a dual-band impedance transformer and a dual-band power amplifier. By determining a frequency point to be matched and a corresponding matching impedance in two preset frequency bands, the characteristic impedance and the electrical length of each microstrip transmission line used for composing the dual-band impedance transformer are obtained, so as to match the complex impedance of the two frequency bands to the real impedance, and the dual-band matching with controllable bandwidth ratio is realized. Furthermore, the dual-band power amplifier with controllable bandwidth ratio is composed based on the designed dual-band impedance transformer.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a dual-band impedance converter and a dual-band power amplifier. Background Technology

[0002] With the rapid development of wireless communication technology, the 5G era has fully arrived, and wireless mobile communication systems are facing a series of new challenges. As a core component of radio frequency transmission systems, power amplifiers face rapidly increasing demands on energy consumption, efficiency, bandwidth, and size. Currently, power amplifiers in related technologies suffer from narrow bandwidth in each frequency band, complex harmonic control, and an inability to control the bandwidth of each frequency band.

[0003] Impedance matching is a common operating condition in radio technology, reflecting the power transfer relationship between input and output circuits. Impedance mismatch can damage the circuit. Therefore, impedance transformers are needed to achieve impedance matching and ensure maximum power transfer. However, impedance transformers in related technologies cannot control the bandwidth ratio of dual-band circuits; the bandwidths of the two bands must be the same. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a dual-band impedance converter and a dual-band power amplifier to solve or partially solve the above problems.

[0005] In a first aspect, this application provides a dual-band impedance converter, comprising:

[0006] First microstrip transmission line, second microstrip transmission line, third microstrip transmission line, fourth microstrip transmission line and fifth microstrip transmission line;

[0007] Wherein, the first end of the second microstrip transmission line is connected to the first microstrip transmission line, and the second end of the second microstrip transmission line is connected to the third microstrip transmission line and the fifth microstrip transmission line respectively;

[0008] The first end of the third microstrip transmission line is connected to the second end of the second microstrip transmission line, and the second end of the third microstrip transmission line is connected to the fourth microstrip transmission line.

[0009] Optionally, the characteristic impedance and electrical length of each segment of the microstrip transmission line are calculated based on the first impedance, the second impedance, the first frequency to be matched, the second frequency to be matched, and the third frequency to be matched, respectively.

[0010] Wherein, the first impedance corresponds to the first frequency band; the second impedance corresponds to the second frequency band;

[0011] The first and second frequency points to be matched are the side frequencies of the first frequency band; the third frequency point to be matched is the center frequency of the second frequency band.

[0012] Optionally, the bandwidth ratio of the first frequency band to the second frequency band can be controlled; the bandwidth of the first frequency band is set according to the frequency interval between the first frequency point to be matched and the second frequency point to be matched.

[0013] Optionally, the first microstrip transmission line is configured to convert the first complex impedance of the first frequency band into a first real impedance;

[0014] The second, third, fourth, and fifth microstrip transmission lines are configured to match the first real impedance and the second complex impedance to a 50-ohm load, respectively; wherein the second complex impedance is obtained by passing the second impedance through the first microstrip transmission line.

[0015] A second aspect of this application provides a dual-band power amplifier, comprising:

[0016] Signal input terminal, signal output terminal, power amplifier tube, input matching network, harmonic control network, and dual-band impedance converter as described in the first aspect;

[0017] The power amplifier tube is configured to amplify the input signal;

[0018] The input matching network, connected to the gate of the power amplifier tube and the signal input terminal, is configured to match the optimal source impedance to the 50-ohm input port.

[0019] The harmonic control network, connected to the drain of the power amplifier tube and the dual-band impedance converter, is configured to match the second harmonic.

[0020] The dual-band impedance converter, connected to the signal output terminal, is configured to match the first impedance and the second impedance to a 50-ohm load terminal, respectively.

[0021] Optionally, the bandwidth ratio of the two bands of the dual-band power amplifier is controlled based on the dual-band impedance transformer.

[0022] Optionally, the dual-band power amplifier further includes: a first bias circuit, a second bias circuit, and a stabilization circuit;

[0023] The first bias circuit and the second bias circuit are respectively connected to the gate and drain of the power amplifier tube and are configured to provide DC bias to the power amplifier tube;

[0024] The stabilizing circuit, connected to the gate of the power amplifier tube, is configured to suppress oscillations in the power amplifier tube.

[0025] Optionally, the input matching network includes a broadband matching structure consisting of four cascaded microstrip transmission lines and a parallel microstrip transmission line.

[0026] Optionally, the harmonic control network includes parallel one-eighth wavelength open-circuit microstrip transmission lines and one-quarter wavelength short-circuit transmission microstrip lines, as well as a microstrip transmission line of a preset length connected to the drain of the power amplifier tube.

[0027] As can be seen from the above, the dual-band impedance converter and dual-band power amplifier provided in this application, by determining the matching frequency points and corresponding matching impedances within two preset frequency bands, obtain the characteristic impedance and electrical length of each microstrip transmission line used to form the dual-band impedance converter, thereby matching the complex impedances of the two frequency bands to the real impedances, achieving dual-band matching with controllable bandwidth ratio. Furthermore, a dual-band power amplifier with controllable bandwidth ratio is constructed based on the designed dual-band impedance converter. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of a dual-band impedance converter according to an embodiment of this application;

[0030] Figure 2 The relationship curve between preset parameters and dual-band frequency response in the embodiments of this application;

[0031] Figure 3 This is a frequency response diagram of the dual-band impedance converter according to an embodiment of this application;

[0032] Figure 4 This is a schematic diagram of the structure of a dual-band power amplifier according to an embodiment of this application;

[0033] Figure 5 This is a schematic diagram of the principle of a dual-band power amplifier according to an embodiment of this application;

[0034] Figure 6 The graph shows the output power, drain efficiency, and gain of the dual-band power amplifier according to an embodiment of this application as a function of frequency. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0036] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0037] With the rapid development of wireless communication technology, the 5G era has fully arrived, and wireless mobile communication systems are facing a series of new challenges. As the core component of radio frequency transmission systems, power amplifiers are facing rapidly increasing requirements in terms of energy consumption, efficiency, bandwidth, and size.

[0038] Currently, wireless communication systems suffer from a series of problems, including the coexistence of multiple technologies such as 2G, 3G, 4G, and 5G, resulting in spectrum dispersion, large frequency band spacing, increasing bandwidth, and gradually higher frequencies. Standards such as GSM, CDMA, and WiMax must be met in mobile communication systems, requiring transceivers' front-end power amplifiers to handle multiple frequency bands with varying bandwidths.

[0039] There are three solutions for multi-frequency power amplifiers with a single power tube. The first is a reconfigurable power amplifier, which adds reconfigurable devices such as PIN switches, MOS switches, and varactor diodes to the input and output matching networks to achieve switching between different frequency bands. However, reconfigurable power amplifiers have a large chip area, many switches, high complexity, low power capacity, and many components generate additional nonlinear effects. The second is a broadband power amplifier, suitable for adjacent frequency bands and capable of handling wide-bandwidth modulated signals. However, when its bandwidth exceeds one harmonic, efficiency and bandwidth become mutually restrictive. The last is a dual-band power amplifier, which matches the optimal output and input complex impedances at different frequencies to 50 ohms, achieving efficiency and output power comparable to a single-frequency power amplifier in a single band.

[0040] However, for dual-band power amplifiers in related technologies, each band has a narrow bandwidth, harmonic control is complex, and the ratio of the two bandwidths cannot be controlled.

[0041] Furthermore, impedance matching is a common operating condition in radio technology, reflecting the power transfer relationship between input and output circuits. Impedance mismatch can damage the circuit. Therefore, impedance transformers are needed to achieve impedance matching and ensure power transmission without reflection. However, impedance transformers in related technologies cannot control the bandwidth ratio of dual-band circuits; the bandwidths of the two bands must be the same.

[0042] Therefore, this application provides a dual-band impedance converter and a dual-band power amplifier. By determining the matching frequencies and corresponding matching impedances within two preset frequency bands, the characteristic impedance and electrical length of each microstrip transmission line used to form the dual-band impedance converter are obtained, thereby matching the complex impedances of the two frequency bands to the real impedances, achieving dual-band matching. Furthermore, a dual-band power amplifier with controllable bandwidth ratio is constructed based on the designed dual-band impedance converter.

[0043] It should be noted that the dual-band impedance transformer in this embodiment is designed using microstrip technology. Specifically, the dual-band impedance transformer in this embodiment is based on the connection of several microstrip transmission lines with different characteristic impedances.

[0044] Figure 1 A schematic diagram of the structure of a dual-band impedance converter according to an embodiment of this application is shown. Figure 1 As shown, the dual-band impedance converter includes: a first microstrip transmission line TL1, a second microstrip transmission line TL2, a third microstrip transmission line TL3, a fourth microstrip transmission line TL4, and a fifth microstrip transmission line TL5.

[0045] Specifically, the first end of the second microstrip transmission line TL2 is connected to the first microstrip transmission line TL1, and the second end of the second microstrip transmission line TL2 is connected to the third microstrip transmission line TL3 and the fifth microstrip transmission line TL5 respectively; the first end of the third microstrip transmission line TL3 is connected to the second end of the second microstrip transmission line TL2, and the second end of the third microstrip transmission line TL3 is connected to the fourth microstrip transmission line TL4.

[0046] Furthermore, the characteristic impedance and electrical length of each microstrip transmission line segment are obtained through the following embodiments.

[0047] In some embodiments, the characteristic impedance and electrical length of each segment of the microstrip transmission line are calculated based on a first impedance, a second impedance, a first frequency to be matched, a second frequency to be matched, and a third frequency to be matched, respectively; wherein, the first impedance corresponds to a first frequency band; the second impedance corresponds to a second frequency band; the first frequency to be matched and the second frequency to be matched are side frequencies of the first frequency band; and the third frequency to be matched is the center frequency of the second frequency band.

[0048] In some embodiments, the first impedance is the first optimal output impedance corresponding to the first frequency band; the second impedance is the second optimal output impedance corresponding to the second frequency band.

[0049] In some embodiments, the first frequency band and the second frequency band can be preset, and the bandwidths of the first frequency band and the second frequency band are different. That is, the dual-band bandwidth ratio is greater than 1, wherein the dual-band bandwidth ratio = relative bandwidth of the first frequency band / relative bandwidth of the second frequency band.

[0050] Specifically, the bandwidth of the first frequency band can be set according to the desired matching bandwidth. The bandwidth of the first frequency band is changed by altering the frequency interval between the first and second frequency points to be matched, thereby changing the bandwidth ratio of the two frequency bands. That is, the bandwidth ratio of the first and second frequency bands is controllable, and the bandwidth of the first frequency band is set according to the frequency interval between the first and second frequency points to be matched.

[0051] In some optional embodiments, the frequency band and bandwidth ratio can be controlled according to different application scenarios and requirements. For example, based on the communication frequency bands of the three major domestic operators, two operating frequency bands can be set as 2.28-2.98GHz (26.9% bandwidth) and 3.4-3.6GHz (5.7% bandwidth), with a bandwidth ratio of 4.7. In this way, based on these two initial frequency bands, the two frequency bands and their bandwidth ratio are finally determined by setting parameters.

[0052] In some optional embodiments, the optimal output impedance is determined by load pulling, where the optimal output impedance refers to the impedance value obtained by load pulling. Taking two operating frequency bands of 2.28-2.98 GHz and 3.4-3.6 GHz as examples, simulations show that at 2.6 GHz, the load impedance to be matched is 13 + j8 Ω; at 3.5 GHz, the load impedance to be matched is 10 + j2.8 Ω; where j represents the imaginary part. Furthermore, the load impedance to be matched is impedance matched to 50 ohms.

[0053] The first optimal output impedance (first impedance) and the second optimal output impedance (second impedance) can be expressed as follows: Specifically:

[0054]

[0055] Where @ indicates a certain frequency, f1 represents matching frequency point 1, and f2 represents matching frequency point 2; R 01 R represents the real part of the load impedance in matching band 1. 02 X represents the real part of the load impedance in matching band 2; j represents the imaginary unit, X 01 X represents the imaginary part of the load impedance at matching frequency 1. 02This represents the imaginary part of the load impedance at matching frequency 2.

[0056] It should be understood that, The corresponding frequency point is not necessarily only f1. It is possible that the values ​​corresponding to the frequency points on both sides of f1 can match the optimal output impedance.

[0057] refer to Figure 2 To match the optimal output impedance to 50 ohms at different frequencies, the relationship curve between preset parameters and the frequency response of the dual-band system is shown (where S11 represents return loss). Figure 2 As shown, based on the preset number of matching points, where the number of matching points in the first frequency band is two and the number of matching points in the second frequency band is one, and the set parameter Δf, the first frequency point to be matched, the second frequency point to be matched, and the third frequency point to be matched can be determined as f1+Δf, f1-Δf, and f2, respectively.

[0058] Thus, as Figure 2 As shown, due to the precise matching of the two frequency points, the first frequency band can be represented by a frequency range from f1-Δf to f1+Δf, while the second frequency band (the higher frequency band), due to single-point matching, has a much narrower matching bandwidth compared to the first frequency band (the lower frequency band). It can be understood that the smaller the return loss S11, the better the matching effect. Furthermore, the bandwidth ratio can be changed by altering the value of Δf.

[0059] As an optional embodiment, Figure 2 f1 and f2 can be interchanged. That is, the higher frequency band has two matching points and the lower frequency band has one matching point. The lower frequency band has a much narrower matching bandwidth than the higher frequency band, thus achieving "one wide and one narrow" dual-frequency matching. The specific settings can be configured according to application requirements, and this application does not limit them.

[0060] It is understandable that the number of matching points can be set according to application requirements, for example, Figure 2 There are two matching points for the mid-to-high frequency band and one matching point for the low frequency band. Of course, more than two matching points can also be set, but the feasibility of solving the problem analytically using the algorithm and the final impedance matching effect need to be considered.

[0061] In some optional embodiments, the bandwidth of the wideband and the bandwidth ratio of the two bands can be controlled by the parameter Δf. A larger value for Δf results in a wider bandwidth. For example, when Δf is zero, it is equivalent to the lower band also being a single-point matched band, meaning the lower and higher bands have the same bandwidth and are both narrow; when Δf is 0.4 GHz, the bandwidth of the lower band is approximately 800 MHz.

[0062] In some optional embodiments, the parameter Δf can be adjusted according to the final obtained frequency band and its bandwidth to meet application requirements. Specifically, if the bandwidth obtained according to the set Δf is too narrow and does not meet the requirements, the value of Δf can be further increased; if the bandwidth obtained according to the set Δf is too wide, the value of Δf can be appropriately decreased, thereby controlling the wideband bandwidth and bandwidth ratio to adapt to different application scenarios or design requirements.

[0063] In this way, by setting the parameter Δf and ensuring that the number of matching points in one frequency band is greater than one, the bandwidth of the corresponding frequency band can be extended, thus obtaining a "wide and narrow" dual-band matching. In related technologies, the bandwidths of the two frequency bands of a dual-band power amplifier are equal (i.e., the bandwidth ratio is 1), and the bandwidth ratio is uncontrollable.

[0064] Furthermore, such as Figure 1 As shown, the optimal impedance value obtained through load traction is: Z 01@f1 =R 01 +jX 01 Z 02@f2 =R 02 +jX 02 Each microstrip transmission line is divided into two parts: the first part is the first microstrip transmission line TL1, and the second part is the remaining four microstrip transmission lines.

[0065] In some embodiments, according to equation (1), the complex impedance corresponding to the set lower frequency band matching point (matching operating frequency 1) is converted to a real impedance R1 using the first part (i.e., the first microstrip transmission line TL1) to facilitate subsequent network matching.

[0066]

[0067] After passing through the first microstrip transmission line TL1, the higher frequency points correspond to the complex impedance: Z1(f2) = R 12 +jX 12 Among them, R 12 X represents the real part of the load impedance at operating frequency 2 after the first microstrip transmission line TL1; 12 This represents the imaginary part of the load impedance at the operating frequency 2 following the first microstrip transmission line TL1.

[0068] Furthermore, the second part (i.e., the second microstrip transmission line TL2, the third microstrip transmission line TL3, the fourth microstrip transmission line TL4, and the fifth microstrip transmission line TL5) is implemented using the following algorithm:

[0069]

[0070]

[0071]

[0072]

[0073] Real{Z3(f)}=Real{Z4(f)} (6)

[0074] Imag{Z3(f)}=-Imag{Z4(f)} (7)

[0075] Where k = f / f1, f is equivalent to the independent variable, and since f is the same for a given frequency, the value of k is the same for the same frequency; Z x (f) indicates that at frequency f, along Figure 1 The middle arrow points to the impedance at the terminal (x = 1, 2, 3, 4, 5); Real indicates taking the real part, and Imag indicates taking the imaginary part.

[0076] The aforementioned nonlinear equations are satisfied at the three frequency points f1+Δf, f1-Δf, and f2, and at least eight free parameters can be obtained. Specifically, the characteristic impedance and electrical length of the second microstrip transmission line TL2, the third microstrip transmission line TL3, the fourth microstrip transmission line TL4, and the fifth microstrip transmission line TL5 can be obtained. In practice, optimization algorithms can be used to find the conditions for satisfying the solutions. By setting a maximum error value, the optimization algorithm can obtain a series of satisfactory solutions.

[0077] It should be noted that the solution obtained through algorithmic analysis may not be a single set, but rather multiple sets. Therefore, it is necessary to select an appropriate solution based on the specific application requirements. For example, in some engineering projects, using a larger impedance or electrical length may be difficult to implement or would result in excessive space requirements; in such cases, it is necessary to select suitable characteristic impedance and electrical length.

[0078] Thus, the characteristic impedance and electrical length (Z) of the first microstrip transmission line TL1 are obtained respectively. a θ a The characteristic impedance and electrical length (Z) of the second microstrip transmission line TL2. b θ b The characteristic impedance and electrical length (Z) of the third microstrip transmission line TL3. c θ c Characteristic impedance and electrical length (Z) of the fourth microstrip transmission line TL4 d θ d Characteristic impedance and electrical length (Z) of the fifth microstrip transmission line TL5 e θ e Then connect these microstrip transmission lines and check if they meet the requirements. Figure 2The matching effect is such that a "wide and narrow" dual-band matching can be obtained. If this is achieved, an impedance transformer for dual-band matching is obtained.

[0079] Thus, when the load impedance to be matched needs to be compatible with a 50-ohm system ( Figure 1 China-Israel Z L When interconnecting (represented by [example]), a dual-band impedance transformer is inserted between the connection points to achieve impedance matching. Furthermore, the dual-band impedance transformer in this embodiment can achieve "one wide and one narrow" dual-band matching with good matching performance.

[0080] Specifically, the first microstrip transmission line is configured to convert the first complex impedance of the first frequency band into the first real impedance; the second, third, fourth and fifth microstrip transmission lines are configured to match the first real impedance and the second complex impedance to a 50-ohm load terminal respectively; wherein the second complex impedance is obtained by passing the second impedance through the first microstrip transmission line.

[0081] In some alternative embodiments, the value of the first real impedance determines the in-band matching effect of the first frequency band. Selecting a smaller value can reduce in-band matching ripple and achieve a better matching effect.

[0082] Furthermore, in some alternative embodiments, the circuitry that performs impedance variation can be mounted on a circuit board. Therefore, to simplify the characteristic parameters of each microstrip transmission line segment, the characteristic impedance and electrical length of each segment can be converted into length and width based on the dielectric constant and thickness of the substrate.

[0083] For example, setting the parameter Δf to 0.2 GHz, the operating frequency bands to 2.28-2.98 GHz and 3.4-3.6 GHz respectively, with a bandwidth ratio of 4.7 between the two bands, and the relative permittivity of the Rogers4350B substrate to 3.66 and a thickness of 20 mil, the characteristic parameters of the microstrip transmission line are obtained as follows:

[0084] The first microstrip transmission line TL1 has a width of 6mm and a length of 22mm;

[0085] The second microstrip transmission line TL2 has a width of 3.1 mm and a length of 29 mm;

[0086] The third microstrip transmission line, TL3, has a width of 7.3 mm and a length of 28 mm.

[0087] The fourth microstrip transmission line, TL4, has a width of 2.2 mm and a length of 17.3 mm.

[0088] The fifth microstrip transmission line, TL5, has a width of 0.6 mm and a length of 2.8 mm.

[0089] Figure 3 The frequency response diagram of a dual-band impedance converter according to an embodiment of this application is shown (S11 represents return loss, S21 represents insertion loss). Figure 3 As shown, precise matching was achieved at 2.4GHz, 2.8GHz, and 3.5GHz, with an S11 below -35dB. In the designed frequency bands of 2.28GHz-2.98GHz (26.9% bandwidth) and 3.4GHz-3.6GHz (5.7% bandwidth), the dual-band bandwidth ratio was 4.7. Its S11 was below -12dB in both bands, achieving excellent matching.

[0090] In addition, this application also provides a dual-band power amplifier.

[0091] refer to Figure 4 This is a schematic diagram of the structure of a dual-band power amplifier according to an embodiment of this application. Figure 4 As shown, the dual-band power amplifier of this application embodiment includes: a signal input terminal, a signal output terminal, a power amplifier tube, an input matching network, a harmonic control network, and the dual-band impedance converter described in the above embodiment;

[0092] The power amplifier tube is configured to amplify the input signal;

[0093] The input matching network, connected to the gate of the power amplifier tube and the signal input terminal, is configured to match the optimal source impedance to the 50-ohm input port.

[0094] The harmonic control network, connected to the drain of the power amplifier tube and the dual-band impedance converter, is configured to match the second harmonic.

[0095] The dual-band impedance transformer, connected to the signal output terminal, is configured to match the first impedance and the second impedance to a 50-ohm load terminal, respectively.

[0096] By combining a harmonic control network with a dual-band impedance transformer as the output matching network of a dual-band power amplifier, the problems of narrow bandwidth in each frequency band, complex harmonic control, and inability to control the bandwidth of each frequency band in existing dual-band power amplifiers are solved. This enables simultaneous achievement of high efficiency, high output power, and frequency band extension in both bands, and allows for dual-band operation with a controllable bandwidth ratio (one wide and one narrow). Furthermore, the bandwidth ratio of the two frequency bands in this dual-band power amplifier is controlled based on the dual-band impedance transformer.

[0097] Figure 5 A more detailed schematic diagram of a dual-band power amplifier is shown. For example... Figure 5As shown, in some optional embodiments, the dual-band power amplifier may further include a bias circuit and a stabilization circuit. Specifically, the bias and stabilization circuit may consist of several capacitors, resistors, and inductors, responsible for providing DC bias to the power amplifier transistors and suppressing oscillations.

[0098] In some alternative embodiments, the bias circuit may include two ( Figure 5 (Not shown in the image), the first bias circuit and the second bias circuit are connected to the gate and drain of the power amplifier transistor, respectively, and are configured to provide DC bias to the power amplifier transistor. Specifically, both the first bias circuit and the second bias circuit can be constructed from a shorted quarter-wavelength microstrip line and a capacitor.

[0099] In some embodiments, a stabilizing circuit, connected to the gate of the power amplifier transistor, is configured to suppress oscillations in the power amplifier transistor. Specifically, the stabilizing circuit may consist of a capacitor and two resistors (a first resistor and a second resistor). Figure 5 As shown, the first resistor is connected in series with the capacitor, and the second resistor is connected in parallel with the capacitor. In this way, by adjusting the values ​​of the resistors and capacitors, the stability factor of the power amplifier can be made greater than or equal to 1 across the entire frequency band.

[0100] In some embodiments, the input matching network includes a broadband matching structure consisting of four cascaded microstrip transmission lines and a parallel microstrip transmission line. This suppresses intermediate frequencies, thereby providing effective matching of the source impedance and achieving matching from the input port to the optimal source impedance. The optimal source impedance is the impedance value obtained by source-pull of the power amplifier transistor.

[0101] In some embodiments, the harmonic control network includes a parallel one-eighth wavelength open-circuit microstrip transmission line and a quarter-wavelength short-circuit transmission microstrip line, and a microstrip transmission line of a predetermined length connected in series with the open-circuit microstrip transmission line. Specifically, a 2.6 GHz one-eighth wavelength open-circuit microstrip line and a 3.5 GHz quarter-wavelength short-circuit microstrip line can be used, with a microstrip line of appropriate length added in front of them to match the second harmonic, thereby improving efficiency and power.

[0102] In some alternative embodiments, the power amplifier tube may be CG2H400010F.

[0103] In some alternative embodiments, such as Figure 5 As shown, the input matching network may further include a DC blocking capacitor, and the dual-band impedance transformer may further include a DC blocking capacitor.

[0104] Furthermore, in some alternative embodiments, the dual-band power amplifier is disposed on a circuit board. Specifically, the circuit board includes a dielectric substrate having a certain thickness. For example, the dielectric substrate Rogers4350B has a relative permittivity of 3.66 and a thickness of 20 mil.

[0105] Figure 6 The diagram illustrates the output power, drain efficiency, and gain of a dual-band power amplifier according to an embodiment of this application as a function of frequency. Figure 6 As shown, within a 700MHz (26.9%) bandwidth between 2.28-2.98GHz, the output power is 40.4-42.7dBm, the drain efficiency is 60-74.6%, and the gain is 11.47-13.67dB; within a 200MHz (5.7%) bandwidth between 3.4GHz-3.6GHz, the output power is 40-41.6dBm, the drain efficiency is 59.8-68%, and the gain is 11-12.6dB. The low-frequency bandwidth is much larger than the high-frequency bandwidth, and the dual-band bandwidth ratio is 4.7, realizing the function of controllable bandwidth ratio and verifying the feasibility of a dual-band power amplifier with controllable bandwidth ratio.

[0106] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this application as described above, which are not provided in the details for the sake of brevity.

[0107] Additionally, to simplify the description and discussion, and to avoid obscuring the embodiments of this application, the well-known power / ground connections to integrated circuit (IC) chips and other components may or may not be shown in the provided drawings. Furthermore, the apparatus may be shown in block diagram form to avoid obscuring the embodiments of this application, and this also takes into account the fact that the details of the implementation of these block diagram apparatuses are highly dependent on the platform on which the embodiments of this application will be implemented (i.e., these details should be fully understood by those skilled in the art). While specific details (e.g., circuits) have been set forth to describe exemplary embodiments of this application, it will be apparent to those skilled in the art that the embodiments of this application can be implemented without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0108] Although this application has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed.

[0109] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A dual-band impedance converter, characterized in that, include: First microstrip transmission line, second microstrip transmission line, third microstrip transmission line, fourth microstrip transmission line and fifth microstrip transmission line; Wherein, the first end of the second microstrip transmission line is connected to the first microstrip transmission line, and the second end of the second microstrip transmission line is connected to the third microstrip transmission line and the fifth microstrip transmission line respectively; The first end of the third microstrip transmission line is connected to the second end of the second microstrip transmission line, and the second end of the third microstrip transmission line is connected to the fourth microstrip transmission line. The characteristic impedance and electrical length of the first microstrip transmission line, the second microstrip transmission line, the third microstrip transmission line, the fourth microstrip transmission line, and the fifth microstrip transmission line are calculated based on their corresponding first impedance, second impedance, first matching frequency, second matching frequency, and third matching frequency, respectively. Wherein, the first impedance corresponds to the first frequency band; the second impedance corresponds to the second frequency band; The first and second frequency points to be matched are the side frequencies of the first frequency band; the third frequency point to be matched is the center frequency of the second frequency band. The bandwidth ratio of the first frequency band to the second frequency band is controllable; the bandwidth of the first frequency band is set according to the frequency interval between the first frequency point to be matched and the second frequency point to be matched.

2. The dual-band impedance converter according to claim 1, characterized in that, The first microstrip transmission line is configured to convert the first complex impedance of the first frequency band into a first real impedance; The second, third, fourth, and fifth microstrip transmission lines are configured to match the first real impedance and the second complex impedance to a 50-ohm load, respectively; wherein the second complex impedance is obtained by passing the second impedance through the first microstrip transmission line.

3. A dual-band power amplifier, characterized in that, include: The signal input terminal, the signal output terminal, the power amplifier tube, the input matching network, the harmonic control network, and the dual-band impedance converter as described in any one of claims 1-2; The power amplifier tube is configured to amplify the input signal; The input matching network, connected to the gate of the power amplifier tube and the signal input terminal, is configured to match the optimal source impedance to the 50-ohm input port. The harmonic control network, connected to the drain of the power amplifier tube and the dual-band impedance converter, is configured to match the second harmonic. The dual-band impedance converter, connected to the signal output terminal, is configured to match the first impedance and the second impedance to a 50-ohm load terminal, respectively.

4. The dual-band power amplifier according to claim 3, characterized in that, The bandwidth ratio of the two frequency bands of the dual-band power amplifier is controlled based on the dual-band impedance transformer.

5. The dual-band power amplifier according to claim 3, characterized in that, The dual-band power amplifier further includes: a first bias circuit, a second bias circuit, and a stabilizing circuit; The first bias circuit and the second bias circuit are respectively connected to the gate and drain of the power amplifier tube and are configured to provide DC bias to the power amplifier tube; The stabilizing circuit, connected to the gate of the power amplifier tube, is configured to suppress oscillations in the power amplifier tube.

6. The dual-band power amplifier according to claim 3, characterized in that, The input matching network includes a broadband matching structure consisting of four cascaded microstrip transmission lines and a parallel microstrip transmission line.

7. The dual-band power amplifier according to claim 3, characterized in that, The harmonic control network includes parallel one-eighth wavelength open-circuit microstrip transmission lines and one-quarter wavelength short-circuit transmission microstrip lines, as well as a microstrip transmission line of a preset length connected to the drain of the power amplifier tube.

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