CN107222173B - Millimeter wave dual-frequency Doherty power amplifier based on single frequency line - Google Patents
Millimeter wave dual-frequency Doherty power amplifier based on single frequency line Download PDFInfo
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- CN107222173B CN107222173B CN201710332251.3A CN201710332251A CN107222173B CN 107222173 B CN107222173 B CN 107222173B CN 201710332251 A CN201710332251 A CN 201710332251A CN 107222173 B CN107222173 B CN 107222173B
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- H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
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- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
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Abstract
The invention provides a millimeter wave dual-frequency Doherty power amplifier based on a single frequency line, which comprises: the dual-frequency power divider is connected with the main power amplifier dual-frequency input matching network through a first single-frequency transmission line with a first preset length, the main power amplifier dual-frequency output matching network is connected with the dual-frequency post-matching network through a second single-frequency transmission line with a second preset length, and the auxiliary power amplifier dual-frequency output matching network is connected with the dual-frequency post-matching network through a third single-frequency transmission line with a third preset length. The invention adopts a common single-frequency transmission line to realize the double-frequency phase shift function, overcomes the problems of large size, high loss and narrow bandwidth of the traditional double-frequency transmission line in a millimeter wave frequency band, and can greatly improve the performance of the double-frequency phase shift line.
Description
Technical Field
The invention relates to the technical field of mobile communication, in particular to a millimeter wave dual-frequency Doherty power amplifier based on a single frequency line.
Background
In modern communication systems, Frequency resources are one of the most scarce resources, and modern modulation methods such as OFDM (Orthogonal Frequency Division Multiplexing) and CDMA (Code Division Multiple Access) are often used to improve spectrum utilization. However, these modern modulation schemes also cause a problem of a Peak to Average Power Ratio (PAPR) while improving the spectrum utilization. Such a high PAPR brings difficulties to the design of the radio frequency front end, especially the radio frequency power amplifier, and especially adversely affects the efficiency index of the power amplifier. The conventional class AB linear power amplifier has a high efficiency around the saturation power, and its efficiency drops sharply when the output power decreases. Since the power amplifier operates in the back-off power region most of the time under high PAPR, the efficiency of class AB power amplifier is far lower than saturation efficiency. It can be said that a high PAPR is one of the difficulties that power amplifiers used in modern communication systems have to cope with.
On the other hand, with the development of communication technology, more and more 3G/4G/5G communication systems are standardized and put into operation, and these communication systems are allocated over a wide frequency band. In this context, it is a normal practice today for the same operator to operate a plurality of communication systems of different modes on a plurality of frequency bands simultaneously. The dual-frequency power amplifier can work in two far-away communication frequency bands, so that the complexity of the radio frequency front end can be greatly reduced, and the dual-frequency power amplifier is widely concerned by equipment manufacturers and operators. In the current 4G base station, the double-frequency power amplifier is already practically applied, and great advantages are shown.
Since the communication frequency band below 6GHz is crowded, in the future 5G communication, in order to greatly increase the communication rate, the millimeter wave frequency band will be adopted. The International Telecommunications Union (ITU) initially established a global feasible frequency list including frequency bands of 24.25-27.5GHz, 31.8-33.4GHz and 37-40.5GHz at the world radio communication conference (WRC-15) held in 2015. The U.S. Federal Communications Commission (FCC) opened the 28GHz, 37GHz, 39GHz, and 64-71GHz millimeter wave bands and incorporated them into the 5G standard. Therefore, a plurality of millimeter wave frequency bands can be adopted in 5G communication, and the requirement for dual-frequency or even multi-frequency millimeter wave power amplification is objectively put forward.
In summary, high PAPR and multiple millimeter wave operating bands will be one of the difficulties and the key points in designing the power amplifier in the 5G communication base station. In order to maintain high efficiency in high PAPR environment, there are many technical solutions available, such as Doherty technology, envelope tracking technology, sequential power amplifier technology, etc., which are known in document 1(RF power amplifiers for Wireless Communications, 2)ndEdition, step c.clips) and the well-known document 2(Advanced technologies in RF Power Amplifier Design, step c.clips) are discussed in detail and will not be repeated here. Among these technologies, the Doherty technology has the advantages of simple structure and high efficiency, and can be replaced with the conventional power amplifier in situ, and becomes the most widely applied high-efficiency power amplifier technology in the communication base station.
For example, as shown in fig. 1, a structure of a conventional Doherty power amplifier is shown, in which two power amplifiers are included, namely a Main power amplifier Main and an auxiliary power amplifier Aux, where Main is biased to class AB and Aux is biased to class C. And at the output end, the Main power amplifier output matching network OMN _ Main and the auxiliary power amplifier output matching network OMN _ Aux are respectively responsible for the output impedance matching of the two power amplifier tubes. The post-match network PMN matches the 50ohm load to 25 ohms. Offset _ Main and Offset _ Aux are phase shift lines having a characteristic impedance of 50 ohms, and are responsible for impedance matching at back-off power. At the input end, the distributor SPLIT divides the input power into two paths, the Main power amplifier input matching network IMN _ Main and the auxiliary power amplifier input matching network IMN _ Aux respectively match the input impedance of Main and Aux to 50 ohms, and the phase shift line Phaseline compensates the phase difference of the Main and auxiliary paths.
The working principle of the traditional Doherty power amplifier can be divided into two areas of a low-power area and a high-power area for analysis, and the two areas use the opening of a C-type auxiliary power amplifier tube as a boundary. In the low power region, the auxiliary power amplifier tube is in an off state, and the Doherty structure requires that Offset _ Aux is reasonably designed, so that Z2B is as close to an open circuit as possible. Since it is an open circuit, when Z1T is 25 ohms, the Doherty structure requires that the combination of Offset _ Main and OMN _ Main can transform 25 ohms to an impedance Z1 as close as possible to ZBO, which is the load impedance that makes Main achieve maximum efficiency at back-off power, and can be obtained by Loadpull method. In summary, since Z2B is open in the low power region, the output circuit of Aux is isolated from the output circuit of Main, and the equivalent circuit is shown in fig. 2.
In the high power region, with the Aux being turned on, Z1T and Z2T gradually change due to the pulling effect of the Aux output signal on the Main output signal, which is called active load pulling effect. At the saturation point, the effect of this pulling effect is maximized, and the operating state of the Doherty power amplifier is shown in fig. 3. As shown in fig. 3, at the saturation point, Z1T and Z2T are equal and both are 50 ohms, whereas the Doherty structure requires that both OMN _ Main and OMN _ Aux can transform the 50ohm load impedance to Z1-Z2-ZSat, respectively. Wherein ZSat is a load impedance which enables the power amplifier tube to achieve the maximum efficiency under saturated power, and can also be obtained by a Loadpull method. Since the characteristic impedances of Offset _ Main and Offset _ Aux are 50 ohms, they have no influence on the matching effect of OMN _ Main and OMN _ Aux.
Due to the impedance pulling effect of Aux, Main can have different load impedances in the low power region and the high power region, and through reasonable design of two phase-shift lines of OMN _ Main and OMN _ Aux and Offset _ Main and Offset _ Aux, Main can have high efficiency in the low power region and the saturation point. Compared with the common AB class power amplifier, the Doherty power amplifier greatly improves the efficiency under the excitation of high PAPR.
In order to design a dual-frequency Doherty power amplifier, an input-output matching network of a main power amplifier and an auxiliary power amplifier is required to be a dual-frequency matching network, and a phase shift line is also required to be a dual-frequency phase shift line, namely, required phase shift can be generated at two design frequencies, and meanwhile, the characteristic impedance of 50Ohm is kept. In the current dual-frequency Doherty design, a dual-frequency line as shown in fig. 4 is often adopted, and the dual-frequency line is a pi-type structure, a T-type structure and a coupling line in sequence from left to right. Although these structures can achieve the effect of dual-frequency phase shift, the size is usually large, the line width may be unreasonable, and the bandwidth is narrow, which limits their application in the millimeter wave frequency band. Due to the strong distributed parameter effect, the millimeter wave power amplifier must be realized by an integrated circuit process, and the larger size of the double-frequency line means a larger chip area, thereby greatly increasing the processing cost. In addition, the loss of the passive element in the millimeter wave frequency band is large, if the size of the double-frequency line is large, the introduced loss can seriously reduce the performance of the power amplifier, and the influence is more obvious when the line width is unreasonable. The integrated circuit process usually has processing errors, and the actual double-frequency phase shift is seriously deviated from a design value due to the excessively narrow bandwidth of a double-frequency line, so that the actually processed double-frequency Doherty power amplifier cannot realize double-frequency performance. Therefore, the difficulty in implementing the millimeter wave dual-frequency Doherty power amplifier lies in implementation of a high-performance dual-frequency phase shift line, and with the acceleration of a 5G communication process, the problem needs to be solved urgently.
Disclosure of Invention
The present invention is directed to solving at least one of the above problems.
Therefore, the invention aims to provide a millimeter wave dual-frequency Doherty power amplifier based on a single-frequency line, which adopts a common single-frequency transmission line to realize a dual-frequency phase shift function, overcomes the problems of large size, high loss and narrow bandwidth of the traditional dual-frequency transmission line in a millimeter wave frequency band, and can greatly improve the performance of the dual-frequency phase shift line.
In order to achieve the above object, an embodiment of the present invention provides a millimeter wave dual-band Doherty power amplifier based on a single frequency line, including: the dual-frequency power amplifier comprises a dual-frequency power distributor, a main power amplifier dual-frequency input matching network, an auxiliary power amplifier dual-frequency input matching network, a main power amplifier tube, an auxiliary power amplifier tube, a main power amplifier dual-frequency output matching network, an auxiliary power amplifier dual-frequency output matching network and a dual-frequency post-matching network, wherein the dual-frequency power distributor, the main power amplifier dual-frequency input matching network, the main power amplifier tube, the main power amplifier dual-frequency output matching network and the dual-frequency post-matching network are sequentially connected; the dual-frequency power distributor, the auxiliary power amplifier dual-frequency input matching network, the auxiliary power amplifier tube, the auxiliary power amplifier dual-frequency output matching network and the dual-frequency post-matching network are sequentially connected; the dual-frequency power distributor is connected with the main power amplifier dual-frequency input matching network through a first single-frequency transmission line with a first preset length, the main power amplifier dual-frequency output matching network is connected with the dual-frequency rear matching network through a second single-frequency transmission line with a second preset length, and the auxiliary power amplifier dual-frequency output matching network is connected with the dual-frequency rear matching network through a third single-frequency transmission line with a third preset length.
In addition, the millimeter wave dual-frequency Doherty power amplifier based on the single-frequency line according to the above embodiment of the present invention may further have the following additional technical features:
in some examples, the dual-frequency power splitter splits input power among a main power amplifier and an auxiliary power amplifier at a first design frequency f1 and a second design frequency f2, wherein the first design frequency f1 is less than the second design frequency f 2.
In some examples, when operating at the first design frequency f1, obtaining a phase shift theta 1 corresponding to a first single-frequency transmission line, a phase shift theta 1 corresponding to a second single-frequency transmission line, and a phase shift theta 1 corresponding to a third single-frequency transmission line, where the theta 1 has a first preset value range; when the antenna works at the second design frequency f2, a phase shift theta 2 corresponding to the first single-frequency transmission line, a phase shift theta 2 corresponding to the second single-frequency transmission line, and a phase shift theta 2 corresponding to the third single-frequency transmission line are obtained, wherein the theta 2 has a second preset value range.
In some examples, the first and second light sources, among others,
f2/f1＝k，
ThetaM2＝k*ThetaM1，
k is the operating frequency ratio.
In some examples, the characteristic impedances of the first, second and third single frequency transmission lines are each 50 ohms.
In some examples, the first design frequency f1 is 28GHz and the second design frequency f2 is 39 GHz.
In some examples, the main power amplifier tube and the auxiliary power amplifier tube are the same, wherein the main power amplifier tube is biased to class AB and the final drain voltage is 4V; the auxiliary power amplifier is biased to be C type, and the final-stage voltage is set to be 4.5V.
In some examples, the main power amplifier tube and the auxiliary power amplifier tube are in a two-stage structure, and the transistor sizes of the driving stage and the power stage are 2X75um and 4X75um respectively.
In some examples, the dual-frequency power splitter is a wide non-halving wilkinson power splitter.
In some examples, the dual-band post-matching network is a two-stage microstrip line structure.
According to the millimeter wave dual-frequency Doherty power amplifier based on the single-frequency line, the common single-frequency transmission line is adopted to realize the dual-frequency phase shift function, the problems of large size, high loss and narrow bandwidth of the traditional dual-frequency transmission line in a millimeter wave frequency band are solved, the performance of the dual-frequency phase shift line can be greatly improved, and the millimeter wave dual-frequency Doherty power amplifier with high performance is facilitated to be realized. In addition, the performance of the common transmission line is insensitive to process errors, so that the reliability of the design is improved.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic diagram of a conventional Doherty power amplifier;
fig. 2 is an equivalent circuit schematic diagram of a conventional Doherty power amplifier in a low power region;
fig. 3 is a schematic diagram of the operation of a conventional Doherty power amplifier at the saturation point of the high power region;
fig. 4 is a schematic structural diagram of a dual-frequency transmission line adopted by the conventional Doherty power amplifier;
fig. 5 is a schematic structural diagram of a millimeter wave dual-frequency Doherty power amplifier based on a single frequency line according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a Doherty power amplifier, which operates at a first design frequency f1, and is based on a single-frequency-line millimeter-wave dual-frequency Doherty power amplifier according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a Doherty power amplifier, which operates at a second design frequency f2 and is based on a single-frequency-line millimeter-wave dual-frequency Doherty power amplifier according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a millimeter wave dual-frequency Doherty power amplifier based on a single frequency line for implementing dual-frequency phase shift with the single frequency line according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a 28GHz/39GHz dual-frequency Doherty power amplifier according to an embodiment of the invention;
fig. 10 is a schematic diagram of an input matching circuit of a dual-frequency power amplifier according to an embodiment of the present invention;
fig. 11 is a schematic diagram of an interstage matching circuit structure of a dual-frequency power amplifier according to an embodiment of the invention;
fig. 12 is a schematic diagram of an output matching circuit of a dual-frequency power amplifier according to an embodiment of the present invention;
fig. 13 is a schematic diagram of a 50-25 ohm dual frequency post-matching network PMN in accordance with an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The millimeter wave dual-frequency Doherty power amplifier based on a single frequency line according to the embodiment of the invention is described below with reference to the accompanying drawings.
Fig. 5 is a schematic structural diagram of a millimeter wave dual-frequency Doherty power amplifier based on a single frequency line according to an embodiment of the invention. As shown in fig. 5, the millimeter wave dual-frequency Doherty power amplifier based on a single frequency line includes: the dual-frequency power divider 110, the main power amplifier dual-frequency input matching network 120, the auxiliary power amplifier dual-frequency input matching network 130, the main power amplifier tube 140, the auxiliary power amplifier tube 150, the main power amplifier dual-frequency output matching network 160, the auxiliary power amplifier dual-frequency output matching network 170 and the dual-frequency post-matching network 180.
The dual-frequency power divider 110, the main power amplifier dual-frequency input matching network 120, the main power amplifier tube 140, the main power amplifier dual-frequency output matching network 160 and the dual-frequency post-matching network 180 are connected in sequence; the dual-frequency power distributor 110, the auxiliary power amplifier dual-frequency input matching network 130, the auxiliary power amplifier tube 150, the auxiliary power amplifier dual-frequency output matching network 170 and the dual-frequency post-matching network 180 are connected in sequence; the dual-frequency power divider 110 is connected to the main power amplifier dual-frequency input matching network 120 through a first single-frequency transmission line 1 of a first preset length, the main power amplifier dual-frequency output matching network 160 is connected to the dual-frequency post-matching network 180 through a second single-frequency transmission line 2 of a second preset length, and the auxiliary power amplifier dual-frequency output matching network 170 is connected to the dual-frequency post-matching network 180 through a third single-frequency transmission line 3 of a third preset length.
In one embodiment of the present invention, the characteristic impedances of the first single-frequency transmission line 1 (see Phaseline in fig. 5), the second single-frequency transmission line 2 (see Offset _ Main in fig. 5), and the third single-frequency transmission line 3 (see Offset _ Aux in fig. 5) are all 50 ohms. That is, throughout the description of fig. 5, Phaseline, Offset _ Main, and Offset _ Aux are ordinary single-frequency transmission lines with characteristic impedance of 50Ohm, and in the embodiment of the present invention, by selecting appropriate lengths, they can simultaneously achieve corresponding phase shifts at two design frequencies.
In one embodiment of the present invention, the dual-frequency power divider 110 reasonably divides the input power to the main power amplifier and the auxiliary power amplifier at a first design frequency f1 and a second design frequency f2, wherein the first design frequency f1 is smaller than the second design frequency f2, i.e., f2> f 1. The main and auxiliary power amplifiers are dual-frequency power amplifiers working at frequencies f1 and f2, and have been independently designed to achieve the best performance, and the performance of the dual-frequency phase shift line directly determines the performance of the dual-frequency Doherty power amplifier.
When the single-frequency transmission line works at the first design frequency f1, a phase shift theta 1 corresponding to the first single-frequency transmission line 1, a phase shift theta 1 corresponding to the second single-frequency transmission line 2, and a phase shift theta 1 corresponding to the third single-frequency transmission line 3 are obtained, wherein the theta 1 has a first preset value range. Specifically, the structure of the Doherty power amplifier implemented at the frequency f1 is shown in fig. 6, where theap 1, theam 1 and theaa 1 are phase shifts corresponding to Phaseline (i.e., the first single-frequency transmission line 1), Offset _ Main (i.e., the second single-frequency transmission line 2) and Offset _ Aux (i.e., the third single-frequency transmission line 3), respectively. In fact, theap 1, theam 1 and theaa 1 do not have to be a set of determined values, and they can still maintain good performance of the Doherty power amplifier when they are varied within a certain range. In an embodiment of the invention, when the theta 1 is set to change in a range (a first preset value range) from theta 11 to theta 12, the change of the rollback efficiency is small, and a high value can be kept.
When the single-frequency transmission line works at the second design frequency f2, a phase shift theta 2 corresponding to the first single-frequency transmission line 1, a phase shift theta 2 corresponding to the second single-frequency transmission line 2, and a phase shift theta 2 corresponding to the third single-frequency transmission line 3 are obtained, wherein the theta 2 has a second preset value range. Specifically, the structure of the Doherty power amplifier implemented at the frequency f2 is shown in fig. 7, where theap 2, theam 2 and theaa 2 are phase shifts corresponding to Phaseline (i.e., the first single-frequency transmission line 1), Offset _ Main (i.e., the second single-frequency transmission line 2) and Offset _ Aux (i.e., the third single-frequency transmission line 3), respectively. Similarly, when the ThetaM2 is changed in the range from ThetaM21 to ThetaM22 (i.e., the second preset value range), the change of the rollback efficiency is small, and a high value can be maintained.
In an embodiment of the present invention, the idea of implementing dual-frequency phase shift by using a single-frequency transmission line is described by implementing Offset _ Main in a dual-frequency Doherty power amplifier. Setting f2/f1 to k, the ratio of the respective phase shifts at f2 and f1 is k for a single frequency line Offset _ Main (second single frequency transmission line) of a specific length (second preset length), i.e., tm 2 is k tm ThetaM1, where k is the operating frequency ratio, corresponding to a straight line a with a slope k in fig. 8. The feasible interval of ThetaM1 is ThetaM11-ThetaM12 (i.e. a first preset value range), the feasible interval of ThetaM2 is ThetaM 21-ThetaM 22 (i.e. a first preset value range), and then, considering the periodicity of the transmission line, the black shaded area in fig. 8 is a reasonable double-frequency phase shift area. The part of the straight line a in the black shaded area is a feasible design interval of Offset _ Main, if the straight line a cannot intersect with the shaded area, the feasible intervals of them 1 and them 2 can be properly widened, and at this time, the dual-frequency performance of the Doherty power amplifier may be reduced, and the performance at f1 and f2 needs to be properly balanced. In fig. 8, ThetaM11 can be taken as the electrical length of Offset _ Main at f1, which has the smallest physical length, or the middle point of the intersection region can be taken, which has stronger robustness. The design method of Offset _ Aux (i.e. the third single-frequency transmission line) and Phaseline (i.e. the first single-frequency transmission line) in the dual-frequency Doherty power amplifier is similar to the design process of Offset _ Main, and is not described herein again.
The double-frequency line designed according to the method is a common transmission line with characteristic impedance of 50Ohm, has reasonable line width, small loss and much smaller size than the traditional double-frequency line, and is suitable for millimeter wave frequency bands. In addition, the performance of the common transmission line is insensitive to process errors, so that the reliability of the design is improved.
In order to better understand the principle of the millimeter wave dual-frequency Doherty power amplifier based on a single frequency line according to the above embodiment of the present invention, the dual-frequency phase shift is implemented by using a single frequency line, and the following detailed description is made by using specific embodiments with reference to the accompanying drawings.
In a specific embodiment of the present invention, for example, the first design frequency f1 is 28GHz, and the second design frequency f2 is 39GHz, i.e., a dual-frequency Doherty power amplifier capable of operating at 28GHz and 39GHz is taken as an example for description.
Specifically, in this embodiment, for example, the dual-frequency Doherty power amplifier is based on a 0.15umpHEMT technology of a WIN semiconductor, the main power amplifier tube 140 and the auxiliary power amplifier tube 150 are the same, that is, the main and auxiliary circuits use the same dual-frequency power amplifier, wherein the main power amplifier is biased to class AB, and the final-stage drain voltage is 4V; the auxiliary power amplifier is biased to be C type, and the final-stage voltage is set to be 4.5V. Further, in order to achieve reasonable gain, the dual-frequency power amplifier adopts a two-stage structure, that is, the main power amplifier tube 140 and the auxiliary power amplifier tube 150 both adopt a two-stage structure, and the transistor sizes of the driving stage and the power stage are 2X75um and 4X75um, respectively. Considering that the operating frequency ratio is only 1.4, the dual-frequency power divider 110 employs a broadband non-halving wilkinson power divider. In this embodiment, the overall structure of the dual-frequency Doherty power amplifier is shown in fig. 9.
Specifically, when the frequency is designed at 28GHz, the electrical length of Offset _ Main is scanned, the optimal electrical length is 65 degrees, and the high rollback efficiency is kept in the range of 40-90 degrees. The Offset _ Aux is scanned to obtain the optimal electrical length of 150, which has better open circuit effect within the range of 145-165 degrees. Phaseline is scanned to obtain the optimal electrical length of 50, and the main and auxiliary circuits still have better power synthesis effect within the range of 30-70 degrees. The specific design results are shown in table 1.
| Offset_Main | Offset_Aux | Phaseline | |
| Feasible interval | 40-90 degrees | 145-165 degree | 30-70 degrees |
| Optimum value | 65 |
150 degree | 50 degree |
TABLE 1
In the same manner, at a frequency of 39GHz, the design results shown in Table 2 below were obtained.
| Offset_Main | Offset_Aux | Phaseline | |
| Feasible interval | 110- | 20-35 degree | 80-100 degree |
| Optimum value | 125 degree | 25 degree | 95 degree |
TABLE 2
According to the principle of realizing dual-frequency phase shift of a single-frequency line, the performances at two working frequencies of 28GHz and 39GHz are balanced at the same time, and the design result of the dual-frequency line shown in the following table 3 is obtained.
| Offset_Main | Offset_Aux | Phaseline | |
| 28GHz | 85 degree | 147 degrees | 65 degree |
| 39GHz | 119 degree | 26 degree | 91 degree |
TABLE 3
Further, in the process adopted in this embodiment, the width of the 50Ohm microstrip line is 70um, and the physical length of the three phase shift lines and the loss at two operating frequencies are shown in table 4 below. Therefore, the loss of the three-section phase shift line in the embodiment is very low, and the advantage of realizing double-frequency phase shift by using a single-frequency line is fully embodied. In addition, the microstrip line is convenient for buckle, can further reduce chip area.
| Offset_Main | Offset_Aux | Phaseline | |
| Physical length | 877um | 1516um | 670um |
| Loss @28GHz | 0.07dB | 0.1dB | 0.05dB |
| Loss @39GHz | 0.09dB | 0.16dB | 0.07dB |
TABLE 4
In this embodiment, the input, inter-stage, and output matching networks of the dual-frequency power amplifier are all dual-frequency matching networks, and simultaneously implement impedance matching at 28GHz and 39GHz, as shown in fig. 10, 11, and 12, respectively. Because the inductance Q value of the millimeter wave frequency band is lower, microstrip lines are used for replacing the inductance Q value in actual implementation.
In the present embodiment, the dual-band post-matching network 180 (i.e., PMN) adopts a two-stage microstrip structure, for example, and can match a 50Ohm load to a 25Ohm load in two operating bands, as shown in fig. 13.
Experimental simulation shows that the dual-frequency Doherty power amplifier described in the embodiment of the invention has good backspacing and saturation performances at 28GHz and 39 GHz.
In summary, according to the millimeter wave dual-frequency Doherty power amplifier based on the single-frequency line in the embodiment of the invention, the common single-frequency transmission line is adopted to realize the dual-frequency phase shift function, so that the problems of large size, high loss and narrow bandwidth of the traditional dual-frequency transmission line in the millimeter wave frequency band are solved, the performance of the dual-frequency phase shift line can be greatly improved, and the millimeter wave dual-frequency Doherty power amplifier with high performance is facilitated to be realized. In addition, the performance of the common transmission line is insensitive to process errors, so that the reliability of the design is improved.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (6)
1. A millimeter wave dual-frequency Doherty power amplifier based on a single frequency line is characterized by comprising: a dual-frequency power divider, a main power amplifier dual-frequency input matching network, an auxiliary power amplifier dual-frequency input matching network, a main power amplifier tube, an auxiliary power amplifier tube, a main power amplifier dual-frequency output matching network, an auxiliary power amplifier dual-frequency output matching network and a dual-frequency post-matching network, wherein,
the dual-frequency power distributor, the main power amplifier dual-frequency input matching network, the main power amplifier tube, the main power amplifier dual-frequency output matching network and the dual-frequency post-matching network are sequentially connected;
the dual-frequency power distributor, the auxiliary power amplifier dual-frequency input matching network, the auxiliary power amplifier tube, the auxiliary power amplifier dual-frequency output matching network and the dual-frequency post-matching network are sequentially connected;
the dual-frequency power distributor is connected with the main power amplifier dual-frequency input matching network through a first single-frequency transmission line with a first preset length, the main power amplifier dual-frequency output matching network is connected with the dual-frequency rear matching network through a second single-frequency transmission line with a second preset length, the auxiliary power amplifier dual-frequency output matching network is connected with the dual-frequency rear matching network through a third single-frequency transmission line with a third preset length, and the characteristic impedances of the first single-frequency transmission line, the second single-frequency transmission line and the third single-frequency transmission line are all 50 ohms;
the dual-frequency power divider reasonably divides input power to a main power amplifier and an auxiliary power amplifier at a first design frequency f1 and a second design frequency f2, wherein the first design frequency f1 is less than the second design frequency f 2;
when the antenna works at the first design frequency f1, obtaining a phase shift theta 1 corresponding to a first single-frequency transmission line, a phase shift theta 1 corresponding to a second single-frequency transmission line and a phase shift theta 1 corresponding to a third single-frequency transmission line, wherein the theta 1 has a first preset value range at f 1; when the antenna works at the second design frequency f2, a phase shift theta 2 corresponding to the first single-frequency transmission line, a phase shift theta 2 corresponding to the second single-frequency transmission line, and a phase shift theta 2 corresponding to the third single-frequency transmission line are obtained, wherein the theta 2 has a second preset value range at f2, wherein,
f2/f1＝k，
ThetaM2＝k*ThetaM1，
k is the operating frequency ratio.
2. The single-frequency-line-based millimeter wave dual-frequency Doherty power amplifier according to claim 1, wherein the first design frequency f1 is 28GHz and the second design frequency f2 is 39 GHz.
3. The single-frequency-line-based millimeter wave dual-frequency Doherty power amplifier of claim 2, wherein the main power amplifier tube and the auxiliary power amplifier tube are the same, wherein,
the main power amplifier is biased to be AB type, and the final drain voltage is 4V;
the auxiliary power amplifier is biased to be C type, and the final-stage voltage is set to be 4.5V.
4. The single-frequency-line-based millimeter wave dual-frequency Doherty power amplifier of claim 3,
the main power amplifier tube and the auxiliary power amplifier tube both adopt a two-stage structure, and the sizes of the transistors of the driving stage and the power stage are respectively 2X75um and 4X75 um.
5. The single-frequency-line-based millimeter wave dual-frequency Doherty power amplifier according to claim 1, wherein the dual-frequency power divider is a wide non-uniform Wilkinson power divider.
6. The single-frequency-line-based millimeter wave dual-frequency Doherty power amplifier according to claim 1, wherein the dual-frequency rear matching network is a two-stage microstrip line structure.
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| CN108616975B (en) | 2018-03-30 | 2020-06-09 | 维沃移动通信有限公司 | Radio frequency system based on millimeter wave communication, method for adjusting transmitting power and terminal |
| CN108718188B (en) * | 2018-04-20 | 2022-02-11 | 杭州电子科技大学 | Broadband high-efficiency Doherty power amplifier and design method thereof |
| CN109450383A (en) * | 2018-11-27 | 2019-03-08 | 江苏大学 | A kind of broadband dual-frequency section Doherty power amplifier based on phase delay double frequency output matching network |
| CN109831164A (en) * | 2019-02-13 | 2019-05-31 | 清华大学 | High rollback efficiency power amplifier based on distributed input/output structure |
| CN111404490A (en) * | 2020-03-25 | 2020-07-10 | 上海洺太电子科技有限公司 | Mixed continuous Doherty power amplifier |
| CN112968672B (en) * | 2021-02-01 | 2022-12-16 | 华南理工大学 | Symmetrical Doherty power amplifier structure and radio frequency transceiver |
| CN112953402A (en) * | 2021-03-22 | 2021-06-11 | 重庆邮电大学 | 5G millimeter wave Doherty power amplifier based on super surface |
| CN116961593A (en) * | 2022-04-12 | 2023-10-27 | 中兴通讯股份有限公司 | Doherty power amplifier, circuit board assembly and electronic equipment |
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| CN103457541B (en) * | 2013-09-12 | 2016-09-28 | 电子科技大学 | A kind of method widening Doherty power amplifier bandwidth and the Doherty power amplifier improved by the method |
| US20150200631A1 (en) * | 2014-01-15 | 2015-07-16 | Alcatel-Lucent Canada Inc. | Dual-band doherty combiner/impedance transformer circuit and doherty power amplifier including the same |
| CN104993796B (en) * | 2015-06-25 | 2018-03-27 | 江苏大学 | A kind of Doherty power amplifier |
| CN105897179A (en) * | 2016-05-10 | 2016-08-24 | 杭州电子科技大学 | Compact wideband Doherty power amplifier and implementation method thereof |
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