CN114285379A - Two-dimensional reconfigurable Doherty power amplifier - Google Patents
Two-dimensional reconfigurable Doherty power amplifier Download PDFInfo
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Abstract
A two-dimensional reconfigurable Doherty power amplifier simultaneously has frequency reconfigurable and average power reconfigurable functions, and comprises: the power divider comprises an equal power divider, a frequency-reconfigurable input matching network of a main power amplifier, a main power tube, a grid power supply end of the main power tube, a drain power supply end of the main power tube, an output harmonic control network of the main power amplifier, an output matching network of the main power amplifier, a frequency-reconfigurable input matching network of an auxiliary power amplifier, an auxiliary power tube, a grid power supply end of the auxiliary power tube, a drain power supply end of the auxiliary power tube, an output harmonic control network of the auxiliary power amplifier, an auxiliary power amplifier of the output matching network of the auxiliary power amplifier, an input phase compensation line, an output phase compensation line and a back matching network. The invention introduces a frequency reconfigurable technology, overcomes the problem that the bandwidth of the traditional dual-frequency/multi-frequency power amplifier is too narrow, changes the direct current bias voltage of the drain power supply ends of the main power tube and the auxiliary power tube to realize the reconfiguration of average power, and meets the working scenes of multiple frequency bands and different optimal output powers.
Description
Technical Field
The invention relates to the technical field of power amplifiers, in particular to a two-dimensional reconfigurable Doherty power amplifier with frequency reconfigurable and average power reconfigurable functions.
Background
With the full coverage deployment of 4G systems and the formal business of 5G, the variety and frequency of channels are increasing, and communication systems of multiple systems will be in a coexistence state for a long time. For a communication base station and an intelligent terminal, it is more important to implement high-efficiency communication in a multi-band mode and a concurrent signaling mode at different frequencies. In addition, as application scenarios are more complex and diversified, the optimal output power required for signal transmission may also change. The power amplifier is used as a key component of the front end of the wireless communication transmitter, and the working performance under the multi-band multi-mode directly determines the multi-band signal processing capability of the wireless communication system. Therefore, there is a need to develop a power amplifier that is compatible with multiple operating frequency bands and can satisfy high performance operation at different output powers.
At present, high-efficiency work under multiple frequencies and multiple modes can be realized through a multiple frequency band technology, an ultra wide band technology and a frequency reconfigurable technology. The multi-band technology can realize the simultaneous work of a plurality of frequency bands, but has the problems of complex circuit structure and narrow bandwidth of a single frequency band; the ultra-wideband technology can fully expand the bandwidth, has the characteristic of simple structure, but cannot achieve high flexibility at the cost of sacrificing other performances; the frequency reconfigurable technology enables the matching network to have dynamic characteristics, high flexibility and high reliability. In order to meet the new challenge that the power amplifier needs to realize high efficiency under different output power states, the average power reconfigurable technology can realize variable output power by changing the supply voltage, and has the characteristics of high flexibility and strong configurability.
The Doherty power amplifier has the characteristic of power back-off quantity, can ensure high-efficiency work under saturated power and back-off power, and has simple structure and convenient debugging. However, the conventional Doherty power amplifier can achieve the best performance only at a fixed operating frequency band and output power.
In summary, the conventional designs have their own disadvantages. In combination with the fact that a current communication system needs to work in multiple frequency bands and in high efficiency under different output power states, it is of great significance to design a two-dimensional reconfigurable Doherty power amplifier which works in multiple frequency bands and multiple output power states.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a Doherty power amplifier capable of realizing frequency reconstruction and average power reconstruction and a design step.
The technical scheme adopted by the invention is as follows:
a two-dimensional reconfigurable Doherty power amplifier comprising: the power amplifier comprises a signal input end, a signal output end, an equal power divider, a main power amplifier, an auxiliary power amplifier, an input phase compensation line, an output phase compensation line and a rear matching network. The main power amplifier comprises a main power amplifier frequency reconfigurable input matching network, a main power tube grid power supply end, a main power tube drain power supply end, a main power amplifier output harmonic control network and a main power amplifier output matching network which are sequentially connected; the auxiliary power amplifier comprises an auxiliary power amplifier frequency reconfigurable input matching network, an auxiliary power tube grid power supply end, an auxiliary power tube drain power supply end, an auxiliary power amplifier output harmonic control network and an auxiliary power amplifier output matching network which are sequentially connected. Wherein, the signal input end is connected with the input end of the equal power divider, two output ends of the equal power divider are respectively connected with the input phase compensation line and the auxiliary power amplifier frequency reconfigurable input matching network, the input phase compensation line is connected with the main power amplifier frequency reconfigurable input matching network, the grid electrode of the main power tube and the power supply end of the drain electrode are respectively connected with the main power amplifier frequency reconfigurable input matching network, the output harmonic control network of the main power amplifier, and the grid electrode of the auxiliary power tube, the power supply end of the drain electrode is respectively connected with an auxiliary power amplifier frequency reconfigurable input matching network and an auxiliary power amplifier output harmonic control network, the auxiliary power amplifier output matching network is connected with an output phase compensation line, the main power amplifier output matching network and the output phase compensation line are combined and then connected with a rear matching network, and the rear matching network is connected with a signal output end. The equal power divider and the rear matching network can normally work in the reconfigurable working frequency band of the Doherty power amplifier.
The two-dimensional reconfigurable Doherty power amplifier has the functions of frequency reconfiguration and average power reconfiguration. The frequency reconfigurable technology realizes the matching of corresponding optimal fundamental wave impedance under different frequency bands by adjusting the bias direct current voltage of the radio frequency switch in the frequency reconfigurable input matching network of the main power amplifier and the frequency reconfigurable input matching network of the auxiliary power amplifier and adjusting the on-off of the switch.
The average power reconfigurable technology simultaneously adjusts the direct current bias voltage of the drain electrode power supply end of the main power tube and the direct current bias voltage of the drain electrode power supply end of the auxiliary power tube, so that the static working point of the power tube is changed, and the power tube can work efficiently under different output power states. The calculation formula is as follows:
(1)
wherein, Vds,high、Vds,lowThe DC bias values of the drain electrode power supply end of the main power tube and the drain electrode power supply end of the auxiliary power tube in the high and low output power states are respectively in the unit of V and PW,highAnd PW,lowHigh and low average output power values, respectively, in units of W. Due to the characteristics of the Doherty power amplifier, after the dc bias voltages of the drain supply terminals of the main power tube and the auxiliary power tube are switched, the dc bias voltage of the gate supply terminal of the auxiliary power tube needs to be adjusted in a matched manner, so as to ensure that the auxiliary power amplifier starts to work at a proper starting point.
The invention has the beneficial effects that:
according to the two-dimensional reconfigurable Doherty power amplifier with the frequency reconfigurable function and the average power reconfigurable function, the frequency reconfigurable technology is introduced into the Doherty power amplifier, so that the problem that the bandwidth of the traditional dual-frequency/multi-frequency power amplifier is too narrow can be solved, the interference of stray signals can be reduced compared with a broadband power amplifier, and better performance can be realized on two discontinuous frequency bands; in addition, by introducing an average power reconfigurable technology, the direct current bias voltage provided by the drain power supply ends of the main power tube and the auxiliary power tube is reduced, and the efficiency of the Doherty power amplifier at low output power is better improved. The invention can meet the application scenes of working under multiple frequency bands and different optimal output powers, is very suitable for the requirement of the modern wireless communication system on the compatibility of multiple modes, and has wide application prospect.
Drawings
Fig. 1 is a schematic structural diagram of a two-dimensional reconfigurable Doherty power amplifier of the invention.
Fig. 2 is a schematic diagram of a wideband load modulation network structure at the output end of the main power amplifier in the present invention.
Fig. 3 is a schematic diagram of a simulation structure of an embodiment of the two-dimensional reconfigurable Doherty power amplifier of the invention.
Fig. 4-1 is a graph of the simulation results of drain efficiency/gain versus output power for the Doherty power amplifier embodiment of the invention (high output power state, 2.4-2.7GHz & switch off).
Fig. 4-2 is a graph of the simulation results of drain efficiency/gain versus output power for the Doherty power amplifier embodiment of the invention (high output power state, 3.4-3.6GHz & switch closed).
Fig. 4-3 are graphs of simulation results of drain efficiency/gain-output power for the Doherty power amplifier embodiment of the invention (-3dB low output power state, 2.4-2.7GHz & switch off).
Fig. 4-4 are graphs of simulation results of drain efficiency/gain-output power for the Doherty power amplifier embodiment of the invention (-3dB low output power state, 3.4-3.6GHz & switch closed).
Fig. 4-5 are graphs of the high output power state and the low output power state at a frequency of 2.5GHz for an embodiment of the Doherty power amplifier of the invention.
Fig. 4-6 are graphs of the high output power state and the low output power state at a frequency of 3.5GHz for an embodiment of the Doherty power amplifier of the invention.
Detailed Description
The present invention will be described in further detail with reference to the following examples and the accompanying drawings.
The invention discloses a two-dimensional reconfigurable Doherty power amplifier, which comprises a signal input end 01, a signal output end 02, an equal power divider 03, a main power amplifier frequency reconfigurable input matching network 04, a main power tube 05, a main power tube grid power supply end 06, a main power tube drain power supply end 07, a main power amplifier output harmonic control network 08, a main power amplifier output matching network 09, an auxiliary power amplifier frequency reconfigurable input matching network 10, an auxiliary power tube 11, an auxiliary power tube grid power supply end 12, an auxiliary power tube drain power supply end 13, an auxiliary power amplifier output harmonic control network 14, an auxiliary power amplifier output matching network 15, an input phase compensation line 16, an output phase compensation line 17 and a back matching network 18, as shown in figure 1. The signal input end 01 and the signal output end 02 are connected with the microstrip line on the dielectric plate through the SMA radio frequency signal adapter.
The main power amplifier is composed of a main power amplifier frequency reconfigurable input matching network 04, a main power tube 05, a main power tube grid power supply end 06, a main power tube drain power supply end 07, a main power amplifier output harmonic control network 08 and a main power amplifier output matching network 09, and the auxiliary power amplifier is composed of an auxiliary power amplifier frequency reconfigurable input matching network 10, an auxiliary power tube 11, an auxiliary power tube grid power supply end 12, an auxiliary power tube drain power supply end 13, an auxiliary power amplifier output harmonic control network 14 and an auxiliary power amplifier output matching network 15. The junction point of the main power amplifier end and the auxiliary power amplifier end at the post-matching network 18 is called a combining point.
The equal-division power divider 03 adopts a broadband Wilkinson structure, and the working bandwidth covers the reconfigurable working frequency band of the Doherty power amplifier. Generally, the reconfigurable operating band is not less than two.
The main power amplifier frequency reconfigurable input matching network 04 and the auxiliary power amplifier frequency reconfigurable input matching network 10 both adopt a T-shaped structure and comprise two sections of series microstrip lines and two sections of parallel microstrip lines, wherein the two sections of series microstrip lines are directly connected, and the two sections of parallel microstrip lines are connected through a radio frequency switch PIN diode and are connected between the two sections of series microstrip lines. By adding bias direct-current voltage at two ends of the radio-frequency switch, the on-off of the radio-frequency switch can be controlled, so that the matching of corresponding optimal fundamental wave impedance under different frequency bands is realized.
The main power amplifier output harmonic control network 08 is used for matching the second harmonic impedance of the main power amplifier on the reconfigurable working frequency band, the auxiliary power amplifier output harmonic control network 14 is used for matching the second harmonic impedance of the auxiliary power amplifier on the reconfigurable working frequency band, and a section of series microstrip line and two sections of parallel microstrip lines are adopted. The calculation method can refer to relevant documents such as passive matching and the like.
The main power amplifier output matching network 09 and the auxiliary power amplifier output matching network 15 both adopt a T-shaped structure, and include two sections of series microstrip lines and one section of parallel microstrip line, and the parallel microstrip line is connected between the two series microstrip lines. As shown in fig. 2, a schematic diagram of structures used in the main power transistor 05, the main power amplifier output harmonic control network 08 and the main power amplifier output matching network 09 is shown (since the structures of the auxiliary power transistor 11, the auxiliary power amplifier output harmonic control network 14 and the auxiliary power amplifier output matching network 15 are the same as the main power amplifier, they are not shown separately here), and the main power amplifier output matching network 09 is used to make the whole including the power transistor equivalent parasitic parameter model 20, the main power amplifier output harmonic control network 08 and the main power amplifier output matching network 09 exhibit broadband fundamental wave load modulation characteristics, that is, the broadband load modulation network 21 of the main power amplifier needs to realize R fundamental wave load modulation characteristics under saturation poweroptTo RoptMatching and main power amplifier in back-off power the broadband load modulation network 21 needs to implement 2RoptTo RoptMatching of/2 (where RoptThe optimal fundamental wave load impedance value of the equivalent current source port of the power tube when the power tube works in the B-type state), and the working frequency band of the power tube needs to contain all reconfigurable working frequency bands. Auxiliary power tube 11, auxiliary power amplifier output harmonic control network 14 and auxiliary power amplifier output matching network 15 groupBecomes a broadband fundamental wave impedance matching network, and is different from the broadband load modulation network 21 in the main power amplifier, the network only needs to ensure 2R under the saturation power of the main power amplifieroptTo RoptMatching of/2.
The characteristic impedance of the input phase compensation line 16 is an output terminal load value (generally 50 Ω) of the equal division power divider, and the characteristic impedance of the output phase compensation line 17 is RoptThe corresponding electrical length should be determined according to the operating frequency band, the phase difference between the main power amplifier branch and the auxiliary power amplifier branch, and the like.
The rear matching network 18 adopts a broadband matching network based on a step impedance transformation line, the working frequency band needs to contain all reconfigurable working frequency bands, and R at the slave combining point is realizedoptMatching of 2 to 50 omega.
The design method of the two-dimensional reconfigurable Doherty power amplifier is introduced below. Firstly, a two-dimensional reconfigurable Doherty power amplifier with working frequency ranges of 2.4-2.7GHz and 3.4-3.6GHz and a difference of 3dB between high and low average output power states is selected as an embodiment. The main power tube and the auxiliary power tube are both GaN HEMT devices CGH40010F produced by CREE, the radio frequency switch is a PIN diode SMP1345_079LF produced by Skyworks, a Rogers4350B dielectric plate is selected, the dielectric constant is 3.66, and the plate thickness is 20mil (0.508 mm). The design steps are as follows:
step 1: designing an auxiliary power amplifier
Step 1-1: firstly, determining a static working point of a power tube, designing a stabilizing circuit, and obtaining the required target impedance through source traction and load traction simulation. Since the auxiliary power amplifier operates in the class-C state, the gate-source voltage V in the high output power state (i.e. the optimal output power of the power tube for the present embodiment) is determinedgs.p.high-6.6V, drain-source voltage V ds.p.high28V. After calculation by the formula (1), determining the grid source voltage V in a low output power state with the difference of 3dB with the high output powergs.p.low-5.8V, drain-source voltage V ds.p.low20V. The proper stabilizing circuit is designed to ensure that the power tube can stably work under the excitation of a large signal, and then the auxiliary power tube with the stabilizing circuit is arrangedAnd performing source traction and load traction simulation, and respectively obtaining the optimal input fundamental wave impedance, output fundamental wave impedance and output second harmonic wave impedance of each frequency point under the reconfigurable frequency band in a high output power state and a low output power state.
Step 1-2: the auxiliary power amplifier frequency reconfigurable input matching network 10 is designed. The specific method comprises the following steps: according to the optimal input fundamental wave impedances of the 2.4-2.7GHz and 3.4-3.6GHz frequency bands in the high and low output power states obtained in the step 1-1, the T-shaped structure is adopted, and the specific parameters of each branch are continuously optimized, so that the auxiliary power amplifier frequency reconfigurable input matching network 10 can achieve better matching in both frequency bands. The final structure is TL in FIG. 326,TL27,TL28,TL29And SW2Specific parameters of the microstrip lines are shown in table 1. The radio frequency switch state corresponds to the power amplifier operating frequency band as shown in table 2. As can be seen from Table 2, when the RF switch SW is turned on2When the power amplifier is disconnected, the auxiliary power amplifier works in a frequency band of 2.4-2.7 GHz; when SW2When closed, the auxiliary power amplifier works in a frequency band of 3.4-3.6 GHz.
In fig. 3, the main power amplifier frequency reconfigurable input matching network 04 and the auxiliary power amplifier frequency reconfigurable input matching network 10 already include auxiliary circuits such as a stabilization circuit and an input bias circuit, and since these auxiliary circuits belong to known parts and do not belong to the inventive content related to the present invention, they are not described in detail here.
Step 1-3: the auxiliary power amplifier output harmonic control network 14 is designed. For the output end of the auxiliary power tube, firstly, second harmonic impedance matching is carried out, the optimal output second harmonic impedances of the 2.4-2.7GHz frequency band and the 3.4-3.6GHz frequency band in the high and low output power states obtained in the simulation of the step 1-1 are compared and analyzed to obtain a common optimal output second harmonic impedance area, the auxiliary power amplifier output harmonic control network 14 is designed according to the structure shown in the figure 2, the actual conditions such as circuit complexity and the like are comprehensively considered, two sections of series microstrip lines are combined into one section of series microstrip line, and the final structure is the TL structure in the figure 316,TL17,TL18Specific parameters of the microstrip lines are shown in table 1.
Step 1-4: the auxiliary power amplifier output matching network 15 is designed. Then, fundamental impedance matching is performed, and design is performed by using a low-pass matching structure according to the optimal output fundamental impedance obtained in the simulation of step 1-1, resulting in TL shown in FIG. 319,TL20,TL21The specific parameters of the formed auxiliary power amplifier output matching network 15 can be seen in table 1. The network can realize the 2R secondary power under the high output power state and the low output power state and in two reconfigurable frequency bandsopt34 Ω to the optimum fundamental impedance of the power tube.
Step 2: designing a main power amplifier
Step 2-1: firstly, determining a static working point of a power tube, designing a stabilizing circuit, and obtaining the required target impedance through source traction and load traction simulation. The design procedure is similar to that of step 1-1, except that the main power amplifier operates in a deep class AB state to determine the gate-source voltage V in a high output power stategs.c.high2.9V, drain-source voltage V ds.c.high28V. After calculation by the formula (1), determining the grid source voltage V under the low output power which is different from the high output power by 3dBgs.c.low2.9V, drain-source voltage V ds.c.low20V. Similarly, the optimal input fundamental wave impedance, output fundamental wave impedance and output second harmonic wave impedance of each frequency point under the reconfigurable frequency bands of 2.4-2.7GHz and 3.4-3.6GHz can be obtained respectively in the high output power state and the low output power state.
Step 2-2: the main power amplifier frequency reconfigurable input matching network 04 is designed. The specific method comprises the following steps: according to the optimal input fundamental wave impedances of the 2.4-2.7GHz and 3.4-3.6GHz frequency bands in the high and low output power states obtained in the step 2-1, the T-shaped structure is adopted, and the specific parameters of each branch are continuously optimized, so that the main power amplifier frequency reconfigurable input matching network 04 can realize better matching in both the two frequency bands. The final structure is TL in FIG. 3 and Table 111,TL12,TL13,TL14And SW1As shown. The radio frequency switch state corresponds to the power amplifier operating frequency band as shown in table 2. From Table 2, it can be seen that when the radio frequency is appliedSwitch SW1When the power amplifier is disconnected, the main power amplifier works in a frequency band of 2.4-2.7 GHz; when SW1When closed, the main power amplifier works in a frequency band of 3.4-3.6 GHz.
Step 2-3: the main power amplifier output harmonic control network 08 is designed. For the output end of the main power tube, firstly, second harmonic impedance matching is carried out, and the optimal output second harmonic impedance of the 2.4-2.7GHz frequency band and the optimal output second harmonic impedance of the 3.4-3.6GHz frequency band in the high and low output power states obtained in the simulation of the step 2-1 are compared and analyzed to obtain a common optimal output second harmonic impedance area. The main power amplifier output harmonic control network 08 is designed using the structure shown in fig. 2, the final structure is TL in fig. 3 and table 1, as in the method of designing the auxiliary power amplifier output harmonic control network1,TL2,TL3As shown. As can be seen from the simulation results, the second harmonic control effect of the main power amplifier output harmonic control network 08 is not as good as that of the auxiliary power amplifier output harmonic control network 14, but it has a characteristic of controlling the second harmonic simultaneously in the two states of saturation and back-off.
Step 2-4: the main power amplifier output matching network 09 is designed. And (3) after the second harmonic impedance matching is finished, performing fundamental wave impedance matching, and designing the broadband load modulation network 21 by combining impedance matching in saturation and backspacing states according to the optimal output fundamental wave impedance obtained in the simulation of the step 2-1. Since step 2-3 has completed the main power amplifier output harmonic control network 08, next the main power amplifier output matching network 09 needs to be designed. In consideration of the range of the reconfigurable working frequency band, in order to ensure the performance of the reconfigurable working frequency band, 2.3-3.7GHz is selected as the bandwidth of the broadband load modulation network 21. In addition, impedance matching in high and low output power states is also required to be considered at the same time, and according to the simulation result of the step 2-1, the real part of the optimal output fundamental wave impedance of each frequency band in the-3 dB low output power state has no obvious change and the imaginary part is slightly increased compared with the high output power state. In this step, the optimum output fundamental wave impedance values in the high and low output power states at the respective frequencies are averaged. Through design and optimization, the structure shown in FIG. 3 and Table 1 is finally obtained, wherein TL1,TL2,TL3Controlling second harmonic impedance, TL, at 2.55GHz and 3.5GHz central frequency points of two reconfigurable working frequency bands4,TL5,TL6Forming the main power amplifier output matching network 09. The whole broadband load modulation network 21 realizes 2R under saturation power at 2.3-3.7GHzoptTo RoptMatching of/2 and R at back-off poweroptTo RoptIs matched.
And step 3: the power divider 03 is designed to be equally divided. The equal power divider 03 adopts a broadband Wilkinson structure, and selects a working frequency band of 2.3-3.7GHz to ensure the normal operation of the Doherty power amplifier, and specific parameters are shown in fig. 3 and table 1.
And 4, step 4: the matching network 18 is designed. The rear matching network adopts a broadband matching network based on a step impedance transformation line, the bandwidth of the rear matching network covers the working frequency band of the Doherty power amplifier, and the parameter of the microstrip line finally adopted after optimization is Wp1＝3.25、Lp1＝14.6、Wp2＝1.76、Lp2＝15.5、Wp3＝0.5、Lp35.4 (unit: mm), realize from the combination point R opt17 Ω to 50 Ω matching.
And 5: and performing simulation and integral optimization, thereby improving the integral performance of the two-dimensional reconfigurable Doherty power amplifier. After the design of each part in the above steps is completed, further optimization needs to be performed for the influence between the main path and the auxiliary path in the Doherty power amplifier, and the specific steps are as follows: firstly, optimizing a main power amplifier input phase compensation line 16 and an auxiliary power amplifier output phase compensation line 17 to ensure that signals of a combining point are in the same phase, thereby maximizing output power; adjusting the grid voltage Vgs.p of the auxiliary power amplifier, finely adjusting the starting time of the auxiliary power tube, ensuring that the auxiliary power amplifier is in a starting critical state when the main power amplifier is saturated, and optimizing and debugging the grid source voltage V in a high-output power stategs.p.high-7.2V, gate-source voltage V at low output powergs.p.low-6V. After the above optimization and the fine tuning of each microstrip line, a circuit diagram of the two-dimensional reconfigurable Doherty power amplifier shown in this embodiment is shown in fig. 3, where each microstrip line is configured to be a microstrip lineMicrostrip lines and element parameters are shown in table 1.
TABLE 1 two-dimensional reconfigurable Doherty power amplifier circuit microstrip line and element parameter table
TABLE 2 radio frequency switch state and two-dimensional reconfigurable working mode corresponding to bias voltage of main and auxiliary power tube
Simulation results of corresponding embodiments of the present invention are presented as shown in fig. 4-1 to 4-5. Fig. 4-1 and fig. 4-2 are simulation curves of drain efficiency and gain varying with output power in a low frequency band and a high frequency band operating frequency band, respectively, in a high output power state. As shown in fig. 4-1, the Doherty power amplifier operates at 2.4-2.7GHz, and at this time, the switch is turned off, the saturated output power is greater than 42.5dBm, the saturated drain efficiency can reach 71%, the 6dB back-off drain efficiency is greater than 52%, and the saturated gain is greater than 8.5 dB; as shown in fig. 4-2, the Doherty power amplifier operates at 3.4-3.6GHz, when the switch is closed, the saturated output power is greater than 42dBm, the saturated drain efficiency is between 61% and 66%, the 6dB back-off drain efficiency is greater than 50%, and the saturated gain is greater than 7.5 dB. Fig. 4-3 and fig. 4-4 are simulation curves of drain efficiency and gain varying with output power in a low frequency band and a high frequency band operating frequency band, respectively, in a low output power state. As shown in fig. 4-3, the Doherty power amplifier operates at 2.4-2.7GHz, and at this time, the switch is turned off, the saturated output power is greater than 39.8dBm, the saturated drain efficiency can reach 71%, the 6dB back-off drain efficiency is greater than 52%, and the saturated gain is greater than 8 dB; as shown in fig. 4-4, the Doherty power amplifier operates at 3.4-3.6GHz, when the switch is turned off, the saturated output power is greater than 39dBm, the saturated drain efficiency is between 60% and 65%, the 6dB back-off drain efficiency is greater than 48%, and the saturated gain is greater than 7 dB. In addition, for the relationship between the higher and lower output power states, the effects at the 2.5GHz and 3.5GHz frequency points are selected respectively for comparison, and the results are shown in fig. 4-5 and fig. 4-6. The 6dB back-off region of the Doherty power amplifier is marked by the hatching a-hatching D, respectively, the hatching B is 3dB different from the hatching a in fig. 4-5, and the hatching D is 3dB different from the hatching C in fig. 4-6, so that it can be seen that the average power output difference between the low output power state and the high output power state is 3dB at the frequency points of 2.5GHz and 3.5 GHz. The simulation results respectively verify that the two-dimensional reconfigurable Doherty power amplifier has the functions of frequency reconfiguration and average power reconfiguration, and can ensure the reasonability and correctness of the structure and theory.
The invention provides a two-dimensional reconfigurable Doherty power amplifier combining a frequency reconfigurable technology and an average power reconfigurable technology, which is characterized in that:
1. compared with the conventional Doherty power amplifier and the reconfigurable power amplifier, the invention can flexibly switch under different frequency bands and different output power states, and can realize high-efficiency work under multi-band and multi-mode.
2. The invention can flexibly switch in the working frequency band which is far away and has wider frequency band through the frequency reconfigurable technology, and in addition, a harmonic control network is introduced at the output ends of the main power amplifier and the auxiliary power amplifier to control the second harmonic, thereby improving the performance under different working frequency bands.
3. The invention enables the power tube to work with high efficiency in a lower output power state by adjusting the static working point of the power tube through an average power reconfigurable technology, and simultaneously combines the advantage of a Doherty power amplifier that the power tube has a backspacing range, and can indirectly expand a high efficiency interval.
The above-described embodiments of the present invention are intended to be illustrative only, and it should be noted that various modifications, improvements, equivalents and other operations may be made within the scope of the present invention, and these operations are also intended to be within the scope of the present invention.
Claims (5)
1. A two-dimensional reconfigurable Doherty power amplifier is characterized by having the functions of frequency reconfiguration and average power reconfiguration simultaneously, and comprising the following steps: the power amplifier comprises a signal input end (01), a signal output end (02), an equal power divider (03), a main power amplifier frequency reconfigurable input matching network (04), a main power tube (05), a main power tube grid power supply end (06), a main power tube drain power supply end (07), a main power amplifier output harmonic control network (08), a main power amplifier output matching network (09), an auxiliary power amplifier frequency reconfigurable input matching network (10), an auxiliary power tube (11), an auxiliary power tube grid power supply end (12), an auxiliary power tube drain power supply end (13), an auxiliary power amplifier output harmonic control network (14), an auxiliary power amplifier output matching network (15), an input phase compensation line (16), an output phase compensation line (17) and a rear matching network (18); the main power amplifier is composed of a main power amplifier frequency reconfigurable input matching network (04), a main power tube (05), a main power tube grid power supply end (06), a main power tube drain power supply end (07), a main power amplifier output harmonic control network (08) and a main power amplifier output matching network (09) which are connected in sequence; the auxiliary power amplifier is composed of an auxiliary power amplifier frequency reconfigurable input matching network (10), an auxiliary power tube (11), an auxiliary power tube grid power supply end (12), an auxiliary power tube drain power supply end (13), an auxiliary power amplifier output harmonic control network (14) and an auxiliary power amplifier output matching network (15) which are connected in sequence.
2. A two-dimensional reconfigurable Doherty power amplifier as claimed in claim 1, wherein the signal input terminal (01) is connected to the input terminal of the equal power divider (03), two output terminals of the equal power divider (03) are respectively connected to the input phase compensation line (16) and the auxiliary power amplifier frequency reconfigurable input matching network (10), the input phase compensation line (16) is connected to the main power amplifier frequency reconfigurable input matching network (04), the auxiliary power amplifier output matching network (15) is connected to the output phase compensation line (17), the main power amplifier output matching network (09) and the output phase compensation line (17) are combined and then connected to the rear matching network (18), and the rear matching network (18) is connected to the signal output terminal (02).
3. The Doherty power amplifier of claim 1, wherein the average power reconfiguration function in the two-dimensional reconfiguration is realized by simultaneously adjusting the DC bias voltages of the drain supply terminals of the main power tube and the drain supply terminals of the auxiliary power tube, and the specific calculation formula is
Wherein Vds,high、Vds,lowThe DC bias values of the drain electrode power supply end of the main power tube and the drain electrode power supply end of the auxiliary power tube in the high and low output power states are respectively in the unit of V and PW,highAnd PW,lowHigh and low average output power values, respectively, in units of W.
4. The two-dimensional reconfigurable Doherty power amplifier of claim 1, wherein the frequency reconfigurable input matching network (04) and the frequency reconfigurable input matching network (10) of the main power amplifier respectively realize the fundamental impedance matching of the main power amplifier and the auxiliary power amplifier on a reconfigurable frequency band, both adopt T-shaped structures and comprise two sections of series microstrip lines and two sections of parallel microstrip lines, wherein the two sections of series microstrip lines are directly connected, the two sections of parallel microstrip lines are connected through a radio frequency switch PIN diode and between the two sections of series microstrip lines, and the on-off of the radio frequency switch can be controlled by adding bias direct current voltage at the two ends of the radio frequency switch, so that the matching of corresponding optimal fundamental impedance under different frequency bands is realized through a frequency reconfigurable technology;
the main power amplifier output harmonic control network (08), the main power amplifier output matching network (09) and the power tube equivalent parasitic parameter model (20) in the main power tube (05) form a broadband load modulation network (21), and the broadband load modulation network (21) is used for enabling the whole body comprising the power tube equivalent parasitic parameter model (20), the main power amplifier output harmonic control network (08) and the main power amplifier output matching network (09) to present broadband fundamental wave load modulation characteristics;
the auxiliary power tube (11), the auxiliary power amplifier output harmonic control network (14) and the auxiliary power amplifier output matching network (15) form a broadband fundamental wave impedance matching network, and the broadband fundamental wave impedance matching network is used for fundamental wave impedance matching of the auxiliary power amplifier on a working frequency band;
the main power amplifier output harmonic control network (08) and the auxiliary power amplifier output harmonic control network (14) are respectively used for matching second harmonic impedances of the main power amplifier and the auxiliary power amplifier on a reconfigurable working frequency band, both adopt dual-frequency matching networks and comprise a section of series microstrip line and two sections of parallel microstrip lines, and the two sections of parallel microstrip lines are simultaneously connected behind the series microstrip line;
the main power amplifier output matching network (09) and the auxiliary power amplifier output matching network (15) both adopt low-pass matching structures and comprise two sections of series microstrip lines and one section of parallel microstrip line, and the parallel microstrip line is connected between the two sections of series microstrip lines.
5. The two-dimensional reconfigurable Doherty power amplifier of claim 1, wherein the impedance of the combining point of the main power amplifier and the auxiliary power amplifier is Ropt/2 wherein RoptWhen the power tube works in a B-type state, the optimal fundamental wave load impedance value of an equivalent current source port of the power tube is obtained; the rear matching network (09) adopts a broadband matching network based on a step impedance transformation line and is used for completing RoptAnd 2, matching to a standard port, wherein the bandwidth covers the operating frequency band of the Doherty power amplifier.
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