Power amplifier and output stage circuit therefor
By employing a matching frequency selection network in the power amplifier circuit, the output impedance of the power transistor and the load impedance are matched, solving the problems of large insertion loss and complex structure in the prior art, improving power transmission efficiency and reducing cost.
Patent Information
- Application Number
- CN202521365057.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2026-08-04
- Estimated Expiration
- 2035-06-30
AI Technical Summary
In existing power amplifier circuits, setting up tuning microstrip circuits, output impedance matching circuits, and multi-stage resonators separately increases circuit insertion loss and results in complex structures and high costs.
A matching frequency selection network, including a parallel LC network, is used to match the output impedance of the power transistor with the load impedance, select signals within the operating frequency band of the power amplifier, and suppress signals outside the operating frequency band. Impedance matching and frequency selection are achieved by adjusting the inductor and capacitor values.
It reduces signal reflection loss, improves overall power transmission efficiency, simplifies circuit structure, and reduces costs.
Smart Images
Figure CN224596448U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power amplifier technology, and in particular to a power amplifier and its output stage circuit. Background Technology
[0002] In power amplifier circuits, the output stage typically requires a tuned microstrip circuit, an output impedance matching circuit, and multiple resonators to reduce signal reflection loss on the transmission line and to process or transmit signals within a specific frequency range. However, separately configuring the tuned microstrip circuit, output impedance matching circuit, and multiple resonators increases insertion loss and results in a complex and costly circuit structure. Utility Model Content
[0003] Therefore, it is necessary to provide a power amplifier with a simple structure and low cost, and its output stage circuit.
[0004] In a first aspect, this application provides an output stage circuit for a power amplifier, including at least one matched frequency selection network; the matched frequency selection network includes:
[0005] The first LC network includes a first inductor unit and a first capacitor unit connected in parallel, wherein a first end of the first inductor unit is used to connect to the first terminal of the power transistor in the power amplifier, and a second end of the first inductor unit is used to connect to the load in the power amplifier.
[0006] The second LC network includes a second inductor unit and a second capacitor unit connected in parallel, wherein the first end of the second inductor unit is connected to the target end of the first inductor unit, and the second end of the second inductor unit is grounded; the target end of the first inductor unit is either the first end or the second end of the first inductor unit.
[0007] The matching frequency selection network is used to match the output impedance of the power transistor with the impedance of the load, and to select the signal within the operating frequency band of the power amplifier.
[0008] In one embodiment, a plurality of matching frequency selection networks are included, wherein a first inductor unit in each matching frequency selection network is connected in series between the first terminal of the power transistor and the load.
[0009] In one embodiment, the difference between the output impedance of the (i+1)th stage matched frequency selection network and the load impedance is less than the difference between the output impedance of the i-th stage matched frequency selection network and the load impedance, where i is greater than or equal to 1, and the i-th stage matched frequency selection network is closer to the power transistor than the (i+1)th stage matched frequency selection network.
[0010] In one embodiment, a first matched frequency selection network and a second matched frequency selection network are connected in series, the first matched frequency selection network being connected to the power transistor and the second matched frequency selection network being connected to the load.
[0011] In one embodiment, in the first matching frequency selection network, the first end of the second inductor unit is connected to the first end of the first inductor unit; in the second matching frequency selection network, the first end of the second inductor unit is connected to the second end of the first inductor unit.
[0012] In one embodiment, the center frequencies of each LC network are different.
[0013] In one embodiment, the inductance values of each inductor unit in each LC network are different, and the capacitance values of each capacitor unit are different.
[0014] In one embodiment, each capacitor unit includes at least one capacitor, and in the case of multiple capacitors, the multiple capacitors are connected in parallel.
[0015] In one embodiment, each inductor unit includes at least one inductor, and in the case of multiple inductors, the multiple inductors are connected in series.
[0016] Secondly, this application also provides a power amplifier, including: a power transistor, a load, and an output stage circuit provided in any of the above embodiments.
[0017] In the aforementioned power amplifier and its output stage circuit, the output stage circuit includes at least one matching frequency selection network. This network can be used to match the output impedance of the power transistor with the impedance of the load, reducing signal reflection loss, selecting signals within the power amplifier's operating frequency band, suppressing signals outside the operating frequency band, and improving overall power transmission efficiency. Further, the matching frequency selection network includes a first LC network and a second LC network. The first LC network includes a first inductor and a first capacitor connected in parallel, and the second LC network includes a second inductor and a second capacitor connected in parallel. This simple circuit structure reduces circuit size and cost. Furthermore, the first terminal of the first inductor is connected to the first terminal of the power transistor in the power amplifier, the second terminal is connected to the load in the power amplifier, the first terminal of the second inductor is connected to the target terminal of the first inductor, and the second terminal is grounded. The signal transmitted to the load only passes through the first LC network, reducing insertion loss. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 One of the schematic diagrams of the output stage circuit of a power amplifier provided in one embodiment;
[0020] Figure 2 A second schematic diagram of the output stage circuit of a power amplifier provided in one embodiment;
[0021] Figure 3 A third schematic diagram of the output stage circuit of a power amplifier provided in one embodiment;
[0022] Figure 4 Schematic diagram four of the output stage circuit of a power amplifier provided in one embodiment;
[0023] Figure 5 A Smith chart showing impedance matching of the output stage circuit of a power amplifier in a specific embodiment;
[0024] Figure 6 The graph shows the transmission coefficient (S21 parameter) of the output stage circuit of the power amplifier in a specific embodiment.
[0025] Figure 7 A schematic diagram of a power amplifier provided in one embodiment.
[0026] Explanation of reference numerals in the attached figures:
[0027] 100 - Matching frequency selection network, 110 - First LC network, 111 - First inductor unit, 112 - First capacitor unit, 120 - Second LC network, 121 - Second inductor unit, 122 - Second capacitor unit, 200 - Output stage circuit, 300 - Input matching circuit, 400 - Load. Detailed Implementation
[0028] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.
[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
[0030] It is understood that the terms "first," "second," etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first LC network may be referred to as a second LC network, and similarly, a second LC network may be referred to as a first LC network. Both the first LC network and the second LC network are LC networks, but they are not the same LC network.
[0031] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.
[0032] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.
[0033] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.
[0034] In one embodiment, such as Figures 1-2 As shown, this application provides an output stage circuit for a power amplifier, which includes at least one matched frequency selection network 100.
[0035] The matching frequency selection network 100 includes a first LC network 110 and a second LC network 120. The first LC network 110 includes a first inductor unit 111 and a first capacitor unit 112 connected in parallel. The first terminal of the first inductor unit 111 is connected to the first terminal of a power transistor in the power amplifier, and the second terminal of the first inductor unit 111 is connected to the load in the power amplifier. The second LC network 120 includes a second inductor unit 121 and a second capacitor unit 122 connected in parallel. The first terminal of the second inductor unit 121 is connected to the target terminal of the first inductor unit 111, and the second terminal of the second inductor unit 121 is grounded. The target terminal of the first inductor unit 111 is either the first terminal or the second terminal of the first inductor unit 111. Figure 1 As shown, the first end of the second inductor unit 121 can be connected to the first end of the first inductor unit 111; optionally, as... Figure 2 In the structure on the right, the second inductor unit 121 can be connected to the second terminal of the first inductor unit 111. The power transistor can be a bipolar transistor, a field-effect transistor, or a thyristor, etc. The first terminal of the power transistor can be the source (or emitter) or the drain (or collector).
[0036] The matching frequency selection network 100 is used to match the output impedance of the power transistor with the impedance of the load, and to select signals within the operating frequency band of the power amplifier. The operating frequency of the power amplifier can be the operating frequency of the power transistor. The inductance values of the first inductor unit 111, the capacitance values of the first capacitor unit 112, the inductance values of the second inductor unit 121, and the capacitance values of the second capacitor unit 122 are all adjustable. It can be understood that by adjusting the inductance values of the first inductor unit 111, the capacitance values of the first capacitor unit 112, the inductance values of the second inductor unit 121, and the capacitance values of the second capacitor unit 122, the output impedance of the power transistor can be matched to the impedance of the load, and the center frequency of the output stage circuit can be made to be the operating frequency of the power amplifier. This preserves signals within the operating frequency band of the power amplifier, suppresses signals outside the operating frequency band, and improves the overall power transmission efficiency.
[0037] In this embodiment, the output stage circuit of the power amplifier includes at least one matching frequency selection network 100. The matching frequency selection network 100 can be used to match the output impedance of the power transistor with the impedance of the load, reduce signal reflection loss, select signals within the operating frequency band of the power amplifier, suppress signals outside the operating frequency band, and improve the overall power transmission efficiency. Further, the matching frequency selection network 100 includes a first LC network 110 and a second LC network 120. The first LC network 110 includes a first inductor unit 111 and a first capacitor unit 121 connected in parallel. The second LC network 120 includes a second inductor unit 121 and a second capacitor unit 122 connected in parallel. The circuit structure is simple, which can reduce circuit size and cost. In addition, the first end of the first inductor unit 111 is connected to the first terminal of the power transistor in the power amplifier, the second end of the first inductor unit 111 is connected to the load in the power amplifier, the first end of the second inductor unit 121 is connected to the target end of the first inductor unit 111, and the second end of the second inductor unit 111 is grounded. The signal transmitted to the load only passes through the first LC network 110, which can reduce circuit insertion loss.
[0038] In one embodiment, such as Figure 2 As shown, the output stage circuit of the power amplifier includes multiple matching frequency selection networks 100. In each matching frequency selection network 100, a first inductor unit 111 is connected in series between the first terminal of the power transistor and the load. Each matching frequency selection network 100 includes a first LC network 110 and a second LC network 120. Each LC network 110 includes a first inductor unit 111 and a first capacitor unit 112 connected in parallel, and each second LC network 120 includes a second inductor unit 121 and a second capacitor unit 122 connected in parallel. It can be understood that by adjusting the inductance value of the first inductor unit 111, the capacitance value of the first capacitor unit 112, the inductance value of the second inductor unit 121, and the capacitance value of the second capacitor unit 122 in each matching frequency selection network 100, the output impedance of the power transistor can be matched to the impedance of the load, and the center frequency of the multiple matching frequency selection networks as a whole can be made the operating frequency of the power amplifier, thereby suppressing signals outside the operating frequency band of the power amplifier.
[0039] In one embodiment, the difference between the output impedance of the (i+1)th stage matched frequency selection network and the load impedance is less than the difference between the output impedance of the ith stage matched frequency selection network and the load impedance. Here, i is greater than or equal to 1. The ith stage matched frequency selection network is closer to the power transistor than the (i+1)th stage matched frequency selection network. It can be understood that since the output impedance of the (i+1)th stage matched frequency selection network is closer to the load impedance than the ith stage matched frequency selection network, multi-stage impedance transformation can reduce the reflection coefficient of a single impedance transformation, further reducing overall reflection loss.
[0040] In one embodiment, such as Figure 3As shown, the output stage circuit of the power amplifier includes a first matching frequency selection network and a second matching frequency selection network connected in series. The first matching frequency selection network is connected to the power transistor, and the second matching frequency selection network is connected to the load.
[0041] The first and second matching frequency selection networks each include a first LC network and a second LC network. For simplicity, the first inductor in the first matching frequency selection network is denoted as L1, the second inductor as L2, the first capacitor as C1, the second capacitor as C2, the first inductor as L3, the first capacitor as C3, the second inductor as L4, and the second capacitor as C4. The first terminal of L1 is connected to the first terminal of the power transistor and the first terminal of L2. The second terminal of L1 is connected to the first terminal of L3. The second terminal of L3 is connected to the first terminal of L4 and the load. The second terminals of both L2 and L4 are grounded.
[0042] In this embodiment, by adjusting the inductance values of L1, L2, L3 and L4, and the capacitance values of C1, C2, C3 and C4, the output impedance of the power transistor can be matched to the impedance of the load, while the center frequency of the output stage circuit is made to be the operating frequency of the power amplifier, so as to suppress signals outside the operating frequency band of the power amplifier. Moreover, the output stage circuit has a simple structure and low cost.
[0043] In one embodiment, the center frequencies of each LC network are different. It is understood that when the output stage circuit of the power amplifier includes a matching frequency selection network 100, the center frequencies of the first LC network 110 and the second LC network 120 are different. When the output stage circuit of the power amplifier includes multiple matching frequency selection networks 100, within the same matching frequency selection network 100, the center frequencies of the first LC network 110 and the second LC network 120 are different, and the center frequencies of the first LC network 110 and the second LC network 120 are different in different matching frequency selection networks 100. Thus, each stage of the matching frequency selection network 100 can filter out some harmonics; for example, the first stage matching frequency selection network can filter out the second harmonic, the second stage matching frequency selection network can filter out the third harmonic, and so on, reducing harmonic tuning complexity and further improving signal transmission efficiency.
[0044] In one embodiment, the inductance value of each inductor element and the capacitance value of each capacitor element in each LC network are different. For example, for... Figure 3In the output stage circuit shown, the inductance values of L1, L2, L3, and L4 are all the same, and the capacitance values of C1, C2, C3, and C4 are all different.
[0045] In one embodiment, each capacitor unit includes at least one capacitor; in the case of multiple capacitors, the multiple capacitors are connected in parallel. For example, as... Figure 4 As shown, each capacitor unit may include multiple capacitors connected in parallel.
[0046] In one embodiment, each inductor unit includes at least one inductor, and in the case of multiple inductors, the multiple inductors are connected in series.
[0047] by Figure 4 Taking the output stage circuit shown as an example, this paper introduces the impedance matching effect and ripple suppression effect of the output stage circuit of the power amplifier in this application. Assume the power transistor's operating frequency is 75MHz, its output impedance is (5.6 + j17)Ω, and the load impedance is 50Ω. The power transistor's output signal passes through... Figure 4 After the output stage circuit shown, as Figure 5 As shown, based on the Smith chart-assisted calculation, the output impedance of the power transistor was matched to (54.178 + j6.362) ohms, achieving matching between the power transistor's output impedance and the load impedance. The transfer coefficient (S21 parameter) curve of this output stage circuit is shown below. Figure 6 As shown, observe Figure 6 As can be seen, the insertion loss at 75MHz is only 0.023dB, while outside the operating frequency band of the power transistor, the insertion loss of signals below 40MHz and above 120MHz is greater than 40dB. This indicates that the output stage circuit provided in this application has a high degree of suppression of noise harmonics and has a good out-of-band suppression effect.
[0048] In one embodiment, this application also provides a power amplifier, such as Figure 7 As shown, it may include a power transistor PA, a load 400, and an output stage circuit 200 provided in any of the above embodiments.
[0049] The output stage circuit of the power amplifier includes at least one matching frequency selection network 100. This network matches the output impedance of the power transistor PA with the impedance of the load 400, reducing signal reflection loss and selecting signals within the power amplifier's operating frequency band while suppressing signals outside the band, thus improving overall power transmission efficiency. Further, the matching frequency selection network 100 includes a first LC network 110 and a second LC network 120. The first LC network 110 includes a first inductor unit 111 and a first capacitor unit 121 connected in parallel, and the second LC network 120 includes a second inductor unit 121 and a second capacitor unit 122 connected in parallel. This simple circuit structure reduces circuit size and cost. Additionally, the first terminal of the first inductor unit 111 is connected to the first terminal of the power transistor PA, and the second terminal is connected to the load 400. The first terminal of the second inductor unit 121 is connected to the target terminal of the first inductor unit 111, and the second terminal is grounded. The signal transmitted to the load only passes through the first LC network 110, reducing insertion loss.
[0050] Since the output stage circuit 200 has the characteristics of simple structure, low cost, good out-of-band rejection and high power transmission efficiency, the power amplifier including the output stage circuit 200 also has the characteristics of simple structure, low cost, good out-of-band rejection and high power transmission efficiency.
[0051] In one embodiment, such as Figure 7 As shown, the power amplifier also includes an input matching circuit 300, which is connected to the control electrode of the power transistor PA and can be used to match the input impedance of the power transistor PA with the impedance of the signal source.
[0052] In the description of this specification, references to terms such as "some embodiments," "other embodiments," 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 descriptions of the above terms do not necessarily refer to the same embodiments or examples.
[0053] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0054] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.
Claims
1. An output stage circuit for a power amplifier, characterized in that, Includes at least one matched frequency selection network; the matched frequency selection network includes: The first LC network includes a first inductor unit and a first capacitor unit connected in parallel, wherein a first end of the first inductor unit is used to connect to the first terminal of the power transistor in the power amplifier, and a second end of the first inductor unit is used to connect to the load in the power amplifier. The second LC network includes a second inductor unit and a second capacitor unit connected in parallel, wherein the first end of the second inductor unit is connected to the target end of the first inductor unit, and the second end of the second inductor unit is grounded; the target end of the first inductor unit is either the first end or the second end of the first inductor unit. The matching frequency selection network is used to match the output impedance of the power transistor with the impedance of the load, and to select the signal within the operating frequency band of the power amplifier.
2. The output stage circuit of the power amplifier according to claim 1, characterized in that, It includes multiple matching frequency selection networks, and the first inductor unit in each matching frequency selection network is connected in series between the first terminal of the power transistor and the load.
3. The output stage circuit of the power amplifier according to claim 2, characterized in that, The difference between the output impedance of the (i+1)th stage matching frequency selection network and the load impedance is less than the difference between the output impedance of the i-th stage matching frequency selection network and the load impedance, where i is greater than or equal to 1, and the i-th stage matching frequency selection network is closer to the power transistor than the (i+1)th stage matching frequency selection network.
4. The output stage circuit of the power amplifier according to claim 2, characterized in that, It includes a first matching frequency selection network and a second matching frequency selection network connected in series. The first matching frequency selection network is connected to the power transistor, and the second matching frequency selection network is connected to the load.
5. The output stage circuit of the power amplifier according to claim 4, characterized in that, In the first matching frequency selection network, the first end of the second inductor unit is connected to the first end of the first inductor unit; in the second matching frequency selection network, the first end of the second inductor unit is connected to the second end of the first inductor unit.
6. The output stage circuit of the power amplifier according to any one of claims 1-5, characterized in that, The center frequency of each LC network is different.
7. The output stage circuit of the power amplifier according to any one of claims 1-5, characterized in that, The inductance values of each inductor unit and the capacitance values of each capacitor unit are different in each LC network.
8. The output stage circuit of the power amplifier according to any one of claims 1-5, characterized in that, Each capacitor unit includes at least one capacitor, and in the case of multiple capacitors, the multiple capacitors are connected in parallel.
9. The output stage circuit of the power amplifier according to any one of claims 1-5, characterized in that, Each inductor unit includes at least one inductor, and in the case of multiple inductors, the multiple inductors are connected in series.
10. A power amplifier, characterized in that, include: The power transistor, the load, and the output stage circuit as described in any one of claims 1-9.