Power amplifier without impedance detection

Abstract

The application discloses a power amplifier without impedance detection and belongs to the technical field of microwave power amplifiers. The power amplifier comprises a power amplifier module, a mismatched impedance correction network module and a circularly polarized radio frequency antenna module. The power amplifier is used for amplifying a power signal. The multi-port mismatched impedance correction network is used for correcting mismatched impedance under a certain mismatched amplitude to a certain fixed impedance, so that the purpose of resisting mismatch is achieved. The radio frequency antenna is used for transmitting the radio frequency power signal to a radio frequency space through the antenna. The application can complete impedance correction without a feedback impedance calculation network. The application can complete mismatched impedance correction of any phase, and the performance loss is only related to VSWR and the correction effect is excellent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microwave power amplifier, and particularly relates to a mismatched impedance correction network structure of a power amplifier without impedance detection. BACKGROUND

[0002] With the development of the wireless communication industry, the requirement for information transmission is higher and higher, and in the field of wireless communication, a high-efficiency radio frequency power amplifier is one of important components of a wireless transceiver system. In order to adapt to the complex environment faced by modern communication, especially the non-standard impedance environment caused by the hand effect in mobile terminals and the like. The change of impedance may affect the power efficiency and linearity of the power amplifier, and therefore the anti-mismatch performance of the power amplifier is concerned by many researchers.

[0003] At present, there are many research directions about the anti-mismatch performance, and most of the research directions are generally based on the performance correction of the power amplifier itself, mainly aiming at the output matching network, bias voltage, drain voltage and the like of the power amplifier. With the in-depth research of scholars, reconfigurable technology, double-input voltage control technology, working state switching and various schemes are continuously proposed. The main principle of the above technologies is to adjust the impedance of the load network or the required impedance of the transistor, so that the two are matched, thereby achieving the purpose of anti-mismatch. The reconfigurable technology mainly adjusts the output matching network after detecting the specific mismatched impedance, so as to adapt to the impedance change and reduce the influence of mismatch. The double-input voltage technology calculates the voltage required by the transistor according to the specific impedance value after detecting the mismatched impedance, and adjusts it, so as to maintain the overall performance of the power amplifier. Mode switching often combines the two ways to change the working state of the power amplifier, thereby achieving the purpose of anti-mismatch.

[0004] At present, there are many researches on the performance recovery when the whole phase is mismatched, but it is not difficult to find that the above methods all need to test the value or approximate range of the mismatched impedance before adjustment, which undoubtedly increases the complexity of system implementation. SUMMARY

[0005] The existing technology can only correct the mismatch in a certain area, and all need to measure the impedance under mismatch, and show different correction effects under different phase mismatches. The application provides a power amplifier without detecting the load impedance, which can realize the self-adaptive adjustment of the port impedance of the power amplifier according to the mismatched impedance of the antenna end face, so as to maintain the port impedance as a fixed value, and thereby maintain the performance of the power amplifier unchanged.

[0006] The structure of the application is as follows Figure 1As shown in the technical scheme: a power amplifier without impedance detection, the power amplifier comprises: a power amplifier module, a mismatched impedance correction network module, a circularly polarized radio frequency antenna module;

[0007] The power amplifier module comprises: a first power divider, a first input matching network, a second input matching network, a main path transistor, an auxiliary path transistor, a first output matching network, a second output matching network, and a post matching network; the input of the entire power amplifier is first divided into two paths by the first power divider, one path sequentially passes through the first input matching network, the main path transistor, and the first output matching network, and the other path sequentially passes through the second input matching network, the auxiliary path transistor, and the second output matching network; the common node of the first input matching network and the main path transistor and the common node of the second input matching network and the auxiliary path transistor are connected to a reference voltage VGG; the common node of the main path transistor and the first output matching network and the common node of the auxiliary path transistor and the second output matching network are connected to an input voltage VDD; and the output of the post matching network is the output of the power amplifier module.

[0008] The mismatched impedance correction network module comprises three DC blocking capacitors, three 1 / 4 wavelength microstrip lines, one resistor, and two matching networks; the input of the mismatched impedance correction network module is the output of the power amplifier module, and after passing through the first DC blocking capacitor, the input is divided into two paths, the first path sequentially passes through the first 1 / 4 wavelength microstrip line and the first matching network, and then connects one end of the circularly polarized antenna after passing through the second DC blocking capacitor; the second path sequentially passes through the second 1 / 4 wavelength microstrip line, the third 1 / 4 wavelength microstrip line, and the second matching network, and then connects the other end of the circularly polarized antenna after passing through the third DC blocking capacitor; the common node of the first 1 / 4 wavelength microstrip line and the first matching network is connected to one end of the resistor, and the common node of the second 1 / 4 wavelength microstrip line and the third 1 / 4 wavelength microstrip line is connected to the other end of the resistor.

[0009] Further, the working frequency band of the power amplifier is 1.7GHz-2.7GHz frequency band.

[0010] Further, the characteristic impedance of the first 1 / 4 wavelength microstrip line and the second 1 / 4 wavelength microstrip line is The characteristic impedance of the third 1 / 4 wavelength microstrip line is Z0, and the impedance of the resistor is 2Z0; Z0 is the port impedance of the impedance correction network and is also the load impedance when the front-end power amplifier is designed.

[0011] Further, the s-parameter matrix of the mismatched impedance correction network module is:

[0012]

[0013] Wherein, a n is the incident wave of the n-port; bn is the n-port reflected wave.

[0014] The application provides a mismatched impedance correction structure based on a multi-port network. The mismatched impedance correction structure is introduced after a power amplifier, and the mismatched performance of the power amplifier is corrected by the anti-mismatched performance under mismatch, and then connected with a radio frequency antenna, so that the anti-mismatched performance of the overall architecture is realized. The application can correct the mismatch under full-phase mismatch by the mismatch correction network without various impedance feedback calculation networks. At the same time, no additional design requirements are proposed for the power amplifier, so that various schemes can be used to realize the advantages of wideband high efficiency, and the anti-mismatched performance under the wideband feedback-free network requirement can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The embodiment of the power amplifier anti-mismatched network provided by the application is shown in the structural diagram;

[0016] Figure 2 The embodiment of the power amplifier provided by the application is shown in the structural diagram;

[0017] Figure 3 The principle diagram of the mismatched impedance correction network provided by the embodiment of the application is shown in the structural diagram;

[0018] Figure 4 The Smith circle diagram of the mismatched impedance provided by the embodiment of the application is shown in the structural diagram;

[0019] Figure 5 The Smith circle diagram of the mismatched impedance after the impedance correction network is corrected is shown in the structural diagram;

[0020] Figure 6 The efficiency result of the power amplifier under the nominal impedance of the embodiment of the application is shown in the structural diagram;

[0021] Figure 7 The efficiency result of the power amplifier under the mismatched impedance of the embodiment of the application is shown in the structural diagram;

[0022] Figure 8 The efficiency result of the power amplifier after the multi-port mismatched impedance correction network of the embodiment of the application is shown in the structural diagram.

[0023] In the figure: a n is the n-port incident wave; b n is the n-port reflected wave; Z0 is the port impedance of the impedance correction network, which is also the load impedance when the front-end power amplifier is designed; Z1, Z2 and Z3 are respectively the port impedances of the mismatched impedance correction networks 1, 2 and 3; Z4 is the port impedance of the output port 3; 1 is the input port of the power amplifier; 2 is the input port of the mismatched impedance correction network; 3 and 4 are the output ports of the mismatched impedance correction network. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, specific embodiments are provided below to further illustrate the invention. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0025] Power amplifiers: These produce high efficiency and output power, require a single-output architecture, and must deliver good output performance at a fixed impedance. They are responsible for providing overall power and efficiency. It's important to note that this power amplifier needs to be designed in conjunction with a subsequent impedance mismatch correction network to achieve impedance correction. For example... Figure 2 A block diagram of a Doherty power amplifier suitable for this scheme is presented. After the signal is input, it is split into two signals by a power divider. These signals are then matched to the optimal input impedance of the transistors via main and auxiliary matching networks, respectively. Subsequently, they are amplified by the main and peak-path transistors, respectively. After output, the signals are matched to the same impedance point by an output matching circuit and then synthesized. Finally, they are matched to a fixed characteristic impedance Z0 by a post-matching network. It is important to note that Z0 here is the same as the port impedance of the subsequent mismatch impedance correction network, thus achieving impedance correction.

[0026] Mismatch impedance correction network: The mismatch impedance correction network can be implemented using a multi-port network. Its main function is to correct the impedance under mismatch conditions to the characteristic impedance of the network, thereby ensuring that the overall performance does not suffer a significant performance loss due to load mismatch. Figure 3 The theoretical analysis diagram of the impedance correction network design is given. The matching network's function is to complete the matching of the circularly polarized antenna under no-mismatch conditions. Since the impedances at ports 2 and 3 are the same, the two matching networks are identical. Therefore, the influence of the DC blocking capacitor and the matching network can be ignored. Its S-parameter matrix is ​​shown below:

[0027]

[0028] In this formula, a n For the incident wave at port n; b n The n-port reflected wave; Z0 in the figure is the port impedance of the impedance correction network, which is also the load impedance in the front-end power amplifier design; Z1, Z2, and Z3 are the impedances of ports 1, 2, and 3, respectively; since ports 2 and 3 are connected to the same circularly polarized antenna, they can have the same mismatch impedance, so Z2 = Z3:

[0029]

[0030]

[0031]

[0032]

[0033]

[0034] Combining the above formula can be obtained:

[0035] b1=0

[0036] At this time b1 is 0, which indicates that there is no reflected wave at port 1, and the port remains Z0 impedance unaffected, and according to the relevant theory, when the output port 2 and the output port 3 are terminated with the same impedance, the input port 1 can satisfy the impedance matching condition, complete the impedance mismatch correction, and the power of the two output ports is the same and the phase difference is 90°, which satisfies the circularly polarized antenna input condition.

[0037] The main function of the radio frequency antenna here is to transmit the received power signal, complete the function of the overall transmitter, and at the same time, the mismatch condition at the antenna end can be reflected to the mismatch correction network through the connection port. The radio frequency antenna here needs to be designed in combination with the mismatch impedance correction network, according to the previous analysis, the two input signals here are two signals with the same size and a phase difference of 90 degrees, which meets the circular polarization input condition, and the circularly polarized antenna can produce consistent mismatch impedance when mismatched, which meets the anti-mismatch condition, so a circularly polarized antenna structure needs to be used here.

[0038] In view of the problems existing in the prior art, the present application provides a power amplifier anti-mismatch structure without impedance calculation network. The main protection point of the present application is the network structure composed of the power amplifier, the multi-port mismatch impedance correction module and the subsequent circularly polarized antenna.

[0039] How the components can be connected and work:

[0040] 1. Signal input: the signal is first input into the power amplifier, which should be designed to meet high efficiency, and the output impedance during design should be consistent with the characteristic impedance of the subsequent device to obtain good impedance correction effect. The signal is amplified and then output to the subsequent mismatch impedance correction network through a single port.

[0041] 2. Impedance correction: the amplified signal is input to the impedance correction network, which inputs the signal to the subsequent radio frequency antenna. The impedance correction network mainly uses a multi-port network to realize the same impedance size when mismatched. As can be known from the previous analysis, under the mismatch condition, the same impedance will be corrected to a fixed impedance through the impedance correction network, thereby maintaining the overall performance unchanged.

[0042] 3. RF antenna: the subsequent power signal is output to the RF antenna network through multiple ports, and is radiated into free space through the antenna port. The RF antenna here can reflect the RF impedance to the impedance correction network connected to the front end. The RF antenna mainly uses a circularly polarized antenna network to achieve this. Circularly polarized antennas not only reflect RF impedance to the front-end correction network, but also complete the RF power transmission of two ports, ensuring overall power performance. Since the characteristic impedance correction network outputs two power amplifiers with the same power and a phase difference of 90°. In order to be able to transmit this power to free space, the use of a circularly polarized antenna can transmit this signal. At the same time, when a mismatch occurs, the mismatched impedance of the circularly polarized antenna can also be corrected by the impedance correction network, thereby reducing the impact on the power amplifier. In addition, it should be noted that in order to ensure the overall performance of the system, the circularly polarized antenna should also be designed to work under the condition of input impedance Z0, thereby completing the overall impedance correction network structure.

[0043] In summary, the structure proposed by the present application includes three modules: a power amplifier module, an impedance correction network, and a circularly polarized antenna module. The main effect of the present application is that it can correct the mismatch under full phase mismatch through the mismatch correction network without the need for various impedance feedback calculation networks.

[0044] As shown in Figure 1 , an embodiment of the present application provides one implementation example.

[0045] The signal enters through input port 1, and then the power signal is output from the output port to the impedance correction network through the power amplifier. At the same time, the power amplifier should work under the condition of a 50-ohm load during design. The impedance correction network is a multi-port network, the graph of which is shown in Figure 3 . According to the previous analysis, this network can satisfy: when the impedances of ports 3 and 4 are consistent, the impedance of port 2 is fixed at 50 ohms. Therefore, when a mismatch occurs, the mismatched impedance will not affect the output port impedance of the power amplifier, thereby maintaining the overall performance under mismatch. The two output power signals have the characteristics of equal power and a phase difference of 90 degrees, which meets the input power requirements of the circularly polarized antenna. Therefore, the signal can be output to the circularly polarized antenna, and the overall antenna power can be radiated into free space.

[0046] The following will describe the mismatch performance correction effect of a specific power amplifier and the multi-port mismatch impedance correction network proposed as an implementation example.

[0047] As shown in Figure 2 : In order to verify the effectiveness of the system, a Doherty power amplifier module applicable to the system is designed, and its characteristic impedance when working is Z0. The power amplifier performance is as shown inFigure 6 As shown in the figure, the saturation power of the amplifier is about 38.5 dBm at a working frequency of 2.2 GHz, and the backoff point efficiency is about 50%.

[0048] As shown in the figure, the mismatched impedance VSWR is 2.0, and eight mismatched impedance points are selected for mismatched impedance correction experiments under 0-360° phase mismatch. Figure 4 As shown in the figure, the mismatched impedance VSWR is 2.0, and eight mismatched impedance points are selected for mismatched impedance correction experiments under 0-360° phase mismatch.

[0049] Figure 5 As shown in the figure, the mismatched impedance VSWR is 2.0, and eight mismatched impedance points are selected for mismatched impedance correction experiments under 0-360° phase mismatch. Figure 4 Figure 5 As shown in the figure, the mismatched impedance VSWR is 2.0, and eight mismatched impedance points are selected for mismatched impedance correction experiments under 0-360° phase mismatch.

[0050] As shown in the figure, the mismatched impedance VSWR is 2.0, and eight mismatched impedance points are selected for mismatched impedance correction experiments under 0-360° phase mismatch. Figure 7 Figure 4 As shown in the figure, the mismatched impedance VSWR is 2.0, and eight mismatched impedance points are selected for mismatched impedance correction experiments under 0-360° phase mismatch.

[0051] As shown in the figure, the mismatched impedance VSWR is 2.0, and eight mismatched impedance points are selected for mismatched impedance correction experiments under 0-360° phase mismatch. Figure 8 Figure 4 As shown in the figure, the mismatched impedance VSWR is 2.0, and eight mismatched impedance points are selected for mismatched impedance correction experiments under 0-360° phase mismatch.

[0052] As shown in the figure, the mismatched impedance VSWR is 2.0, and eight mismatched impedance points are selected for mismatched impedance correction experiments under 0-360° phase mismatch. As can be seen, the embodiment provides a power amplifier mismatching structure without an impedance detection network. After the power signal is amplified by the power amplifier, the mismatched impedance is self-corrected through the multi-port load impedance correction network. Thus, the overall performance is corrected under full-phase mismatch, and the full-phase correction effect is consistent.​​​

[0053] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited thereto, any modification, equivalent replacement and improvement within the technical range disclosed by the present application and within the spirit and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A power amplifier without impedance detection, the power amplifier comprising: A power amplifier module, a mismatched impedance correction network module, and a circularly polarized radio frequency antenna module; The power amplifier module comprises a first power divider, a first input matching network, a second input matching network, a main path transistor, an auxiliary path transistor, a first output matching network, a second output matching network, and a post matching network. The input of the entire power amplifier is first divided into two paths by the first power divider. One path sequentially passes through the first input matching network, the main path transistor, and the first output matching network, and the other path sequentially passes through the second input matching network, the auxiliary path transistor, and the second output matching network. The outputs of the first output matching network and the second output matching network are jointly input to the post matching network. The common node of the first input matching network and the main path transistor and the common node of the second input matching network and the auxiliary path transistor are connected to a reference voltage VGG. The common node of the main path transistor and the first output matching network and the common node of the auxiliary path transistor and the second output matching network are connected to an input voltage VDD. The output of the post matching network is the output of the power amplifier module. The mismatched impedance correction network module comprises three DC blocking capacitors, three 1 / 4 wavelength microstrip lines, one resistor, and two matching networks. The input of the mismatched impedance correction network module is the output of the power amplifier module. After passing through the first DC blocking capacitor, the input is divided into two paths. The first path sequentially passes through the first 1 / 4 wavelength microstrip line and the first matching network, and is connected to one end of the circularly polarized antenna after passing through the second DC blocking capacitor. The second path sequentially passes through the second 1 / 4 wavelength microstrip line, the third 1 / 4 wavelength microstrip line, and the second matching network, and is connected to the other end of the circularly polarized antenna after passing through the third DC blocking capacitor. The common node of the first 1 / 4 wavelength microstrip line and the first matching network is connected to one end of the resistor, and the common node of the second 1 / 4 wavelength microstrip line and the third 1 / 4 wavelength microstrip line is connected to the other end of the resistor.

2. A power amplifier without impedance detection as claimed in claim 1, characterized in that The working frequency band of the power amplifier is 1.7 GHz-2.7 GHz.

3. A power amplifier without impedance detection as recited in claim 1, wherein, The first 1 / 4 wavelength microstrip line has a characteristic impedance of Z0, and the second 1 / 4 wavelength microstrip line has a characteristic impedance of 2Z0. The third 1 / 4 wavelength microstrip line has a characteristic impedance of Z0, and the resistive impedance is 2Z0, Z0 being the port impedance of the mismatch impedance correction network module.

4. A power amplifier without impedance detection as recited in claim 1, wherein, The s-parameter matrix of the mismatched impedance correction network module wherein a n is the incident wave at port n, n = 1, 2, 3; b n is the reflected wave at port n.

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