Power amplifier structure and communication device

Abstract

This application discloses a power amplifier structure and communication device, belonging to the field of radio frequency power amplifier technology. The power amplifier structure includes: a multi-channel power amplifier unit, multiple transformers, an impedance matching network unit, and a power divider. The output of the power divider is coupled to the inputs of the main amplifier and auxiliary amplifiers in each power amplifier unit. The output of the main amplifier is coupled in parallel to the outputs of each auxiliary amplifier in the power amplifier unit through an impedance transformation unit. The primary winding of each transformer is coupled to the parallel coupling node of each power amplifier unit, and the secondary windings of each transformer are connected in series. The first terminal of the impedance matching network unit is coupled in series with the secondary windings of each transformer, and the second terminal of the impedance matching network unit is coupled to the load. The impedance matching network unit is configured to adjust the load impedance at the second terminal so that the first terminal has the optimal load impedance corresponding to the main amplifier. This improves power output, reduces the impedance transformation ratio at two points, and thus expands the bandwidth.

Description

Technical Field

[0001] This application belongs to the field of radio frequency power amplifier technology, and in particular relates to a power amplifier structure and a communication device. Background Technology

[0002] Radio frequency (RF) power amplifiers are core components of the radio frequency (RF) transmission link. Their main function is to amplify the weak electrical signals output from the RF signal source (typically in the milliwatt range, such as -10dBm to 0dBm) to sufficient power (ranging from watts to kilowatts), driving the antenna to radiate the signal into space. They are widely used in wireless communication, radar, satellite communication, and RF testing. Their performance directly determines the coverage, signal quality, and energy efficiency of the communication system. The core efficiency indicator is power-added efficiency (PAE), which reflects the ability to convert electrical energy into RF power. Bandwidth represents the effective operating frequency range and needs to be optimized through a matching network to avoid unbalanced amplification within the frequency band.

[0003] Power capacity, bandwidth, and efficiency are inherent and interdependent performance parameters of RF power amplifiers. Some RF power amplifiers improve linearity by performing power back-off at lower signal voltages, but this leads to a decrease in efficiency. However, the bandwidth and power capacity of current RF power amplifiers still need improvement. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a power amplifier structure and communication device that improves power output, reduces the impedance transformation ratio at both ends of the impedance transformation unit on the output side of the main amplifier in the backoff state, and simultaneously reduces the impedance transformation ratio of the impedance matching network unit, thereby expanding the bandwidth.

[0005] In a first aspect, this application provides a power amplifier structure, including: A multi-channel power amplifier unit, each power amplifier unit includes a main amplifier, at least one auxiliary amplifier and an impedance transformation unit, the output of the main amplifier is coupled in parallel with the output of each auxiliary amplifier through the impedance transformation unit; Multiple transformers, with the primary side of each transformer coupled to the parallel coupling node of each power amplifier unit, and the secondary sides of each transformer connected in series; The impedance matching network unit has its first end coupled in series with the secondary side of each transformer, and its second end coupled with the load. The impedance matching network unit is configured to adjust the load impedance at the second end so that the first end has the optimal load impedance corresponding to the main amplifier. The power divider's output is coupled to the inputs of the main amplifier and auxiliary amplifier in each power amplifier unit.

[0006] According to one embodiment of this application, the main amplifier and the auxiliary amplifier have the same transistor structure, the impedance ratio between the primary side node of the transformer and the secondary side series node of each transformer is 1:N, and the number of auxiliary amplifiers is N-1.

[0007] According to one embodiment of this application, the turns ratios of each transformer are the same.

[0008] According to one embodiment of this application, when the input signal voltage is less than or equal to V... max When / k, the auxiliary amplifier is off, and the impedance transformation unit is configured to adjust the load impedance on the output side of the main amplifier to f(x)N*R. opt And f(x)N / K≥1; Among them, V max R is the maximum value of the input signal voltage when the amplifier is saturated. opt This is the optimal load impedance.

[0009] According to one embodiment of this application, the power amplifier unit has two channels and two transformers, with a turns ratio of 1:1 for both transformers.

[0010] According to one embodiment of this application, the power amplifier unit includes a main amplifier and an auxiliary amplifier, and the impedance transformation unit adopts a characteristic impedance of R. opt λ / 4 impedance transformation line, R opt This is the optimal load impedance.

[0011] According to one embodiment of this application, the impedance matching network element adopts a characteristic impedance of sqrt(50*R). opt The λ / 4 impedance transformation line, R opt This is the optimal load impedance.

[0012] According to one embodiment of this application, the conduction angle of the main amplifier is greater than or equal to 180° and less than or equal to 360°, and the conduction angle of the auxiliary amplifier is less than 180°.

[0013] According to one embodiment of this application, the power amplifier unit further includes: At least one phase compensation unit is provided, and each phase compensation unit is coupled between the input of each auxiliary amplifier and the output of the corresponding power divider.

[0014] Secondly, this application provides a communication device, which includes the power amplifier structure described above.

[0015] According to the power amplifier structure and communication device of this application, the load impedance is converted into the optimal load impedance through the impedance matching network unit, and then the impedance is distributed to the output stage of each power amplifier unit through the transformer. Then, each power amplifier unit performs impedance matching through the impedance transformation unit to achieve high power output. It also reduces the impedance transformation ratio at both ends of the impedance transformation unit on the output side of the main amplifier in the backoff state, and at the same time reduces the impedance transformation ratio of the impedance matching network unit, thereby expanding the bandwidth.

[0016] Additional aspects and advantages of this application 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 this application. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of a Doherty amplifier. Figure 2 This is one of the structural schematic diagrams of the power amplifier structure provided in the embodiments of this application; Figure 3 This is a second schematic diagram of the power amplifier structure provided in the embodiments of this application; Figure 4 This is a graph showing the overall efficiency of the power amplifier structure provided in this application embodiment as a function of input voltage. Figure 5 This is a graph showing the changing trend of the load impedance of the main amplifier in the power amplifier structure provided in the embodiments of this application; Figure 6 This is a comparison chart of the bandwidth characteristics of the normalized load impedance real part of the power amplifier structure. Figure 7 This is a comparison diagram of the bandwidth characteristics of the imaginary part of the load impedance of the power amplifier structure.

[0018] Figure label: Power amplifier unit 10, main amplifier 11, auxiliary amplifier 12, impedance transformation unit 13, phase compensation unit 14, transformer 20, impedance matching network unit 30, power divider 40. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0020] In the following description, a "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by an electrical or electromagnetic link. When an element or circuit is said to be "coupled to" or "connected to" another element, or when an element / circuit is said to be "coupled at" or "connected at" two nodes, it can be directly coupled to or connected to the other element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intermediate elements between them.

[0021] In the description, the terms "first," "second," etc., are used to distinguish similar objects, not to describe a specific order or sequence. It should be understood that such numerical descriptors can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0022] Furthermore, the use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0023] The characteristic of RF power amplifiers is that they have good efficiency when the input power is high, but when the input power decreases, not only does the output power decrease, but the efficiency also decreases. Taking a Class B power amplifier with a conduction angle of π as an example, when the input signal voltage drops to half of its saturation voltage, the efficiency of the power amplifier also decreases by half.

[0024] Let V max I is the maximum amplitude of the input signal voltage. m To output the maximum amplitude of the fundamental current, V dc R is the drain voltage, which is also equal to the maximum amplitude of the output fundamental voltage. opt For the optimal load of the power amplifier tube fundamental frequency, R opt =V dc / I m .

[0025] When the input signal voltage V in =Vmax That is, when the power amplifier is operating in saturation: the fundamental output power P1 = V dc *I m / 2, DC power consumption P dc =2*V dc *I m / π, saturation efficiency DE sat =π / 4. When the input signal voltage V in =V max / k means that when the power amplifier is operating in the backoff state, both the output fundamental voltage and current are reduced to 1 / k of the saturation state, while the DC voltage remains V. dc The DC current also shrinks to 1 / k of the saturation state: fundamental output power P1 = (V dc *I m) / (2*k 2 DC power consumption P dc =2*V dc *I m / (k*π), backoff efficiency DE bo =π / (4*k)=DE sat / k.

[0026] For low-power wireless OFDM (Orthogonal Frequency Division Multiplexing) signals in grid carrier communication, the peak-to-average power ratio is generally 7~8dB. From the perspective of power spectral density, backoff power accounts for most of the time.

[0027] Reference Figure 1 , Figure 1 This is a schematic diagram of a typical Doherty amplifier. The Doherty amplifier includes a main amplifier 11, an auxiliary amplifier 12, and a λ / 4 impedance transformation line. The λ / 4 impedance transformation line is connected to the output of the main amplifier 11 and is connected in parallel with the auxiliary amplifier 12.

[0028] The main amplifier 11 and the auxiliary amplifier 12 have corresponding transistor structures, thus possessing the same current capability. That is, the input signal voltage V of the main amplifier 11 and the auxiliary amplifier 12... in =V max In this case, the main amplifier 11 and the auxiliary amplifier 12 have the same output current I. m .

[0029] The output of a Doherty amplifier is typically also connected to the load via an impedance matching network. The impedance matching network is used to convert the load impedance of the combined output of the Doherty amplifier to a standard system impedance (typically 50Ω) to meet the load's requirements.

[0030] In the Doherty amplifier's back-off power mode, only the main amplifier 11 operates, while the auxiliary amplifier 12 remains inactive. To increase output power, a λ / 4 wavelength impedance transformation line increases the load impedance of the main amplifier 11. The transformation formula for the λ / 4 wavelength impedance transformation line is:

[0031] Where Z0 is the characteristic impedance of the λ / 4 impedance transformation line, and here Z0 = R opt Z1 is the load impedance on the input side, Z A The load impedance on the output side. Phase constant , The length of the impedance transformation line is λ / 4, which is λ / 4. Substituting this into the calculation yields:

[0032] Let the rollback point be V max Taking / 2 as an example, the output current of the main amplifier 11 is I. m / 2, to achieve the maximum output voltage amplitude, the load impedance of the main amplifier 11 needs to be 2R. opt This makes the output voltage V1 = I m / 2*2R opt =V m The output efficiency is the same as in saturation.

[0033] Considering the transformation characteristics of the λ / 4 impedance transformer, the load impedance of the combined output of the Doherty amplifier needs to be R. opt / 2. Therefore, for the entire power amplifier system, when power is returned to normal, the impedance matching network needs to convert the standard system impedance to R. opt / 2, the power amplifier system achieves R opt / 2 to 2R opt The transformation has a high conversion rate; simultaneously, R is achieved at both ends of the impedance matching network. opt The conversion from Ω to 50Ω is relatively high, resulting in a smaller bandwidth.

[0034] To address this, this application proposes a power amplifier structure and communication device. The load impedance is converted to the optimal load impedance through an impedance matching network unit, and then impedance is transformed through a transformer to distribute the impedance to the output stage of each power amplifier unit. Each power amplifier unit then performs impedance matching through an impedance transformation unit to achieve high power output. Furthermore, the impedance transformation ratio at both ends of the impedance transformation unit on the output side of the main amplifier is reduced in the backoff state, and the impedance transformation ratio of the impedance matching network unit is also reduced, thereby expanding the bandwidth.

[0035] Reference Figure 2 , Figure 2This is a schematic diagram of the power amplifier structure provided in an embodiment of this application. One embodiment of this application proposes a power amplifier structure. In this embodiment, the power amplifier structure includes a multi-channel power amplifier unit 10, multiple transformers 20, an impedance matching network unit 30, and a power divider 40. Each power amplifier unit 10 includes a main amplifier 11, at least one auxiliary amplifier 12, and an impedance transformation unit 13. The output of the main amplifier 11 is coupled in parallel with the output of each auxiliary amplifier 12 through the impedance transformation unit 13. The primary side of each transformer 20 is coupled to the parallel coupling node of each power amplifier unit 10, and the secondary side of each transformer 20 is connected in series. The first end of the impedance matching network unit 30 is coupled in series with the secondary side of each transformer 20, and the second end of the impedance matching network unit 30 is coupled to a load 50. The impedance matching network unit 30 is configured to adjust the load impedance at the second end so that the first end has the optimal load impedance corresponding to the main amplifier 11. The output of the power divider 40 is coupled to the inputs of the main amplifier 11 and the auxiliary amplifier 12 in each power amplifier unit 10.

[0036] The power divider 40 is used to distribute a single input signal (from a preamplifier or signal source) to the branches containing the main amplifier 11 and auxiliary amplifier 12. Each amplifier in each branch only needs to handle a portion of the total power, reducing the power load on individual devices and improving reliability and design flexibility.

[0037] The conduction angle of the main amplifier 11 can be greater than that of the auxiliary amplifier 12. The conduction angle refers to the angle corresponding to the time during which current flows through the amplifying device within a complete input signal cycle. The smaller the conduction angle, the shorter the device's conduction time, the lower the power consumption, and the higher the efficiency, but the more severe the waveform distortion and the worse the linearity. The larger the conduction angle, the longer the device's conduction time, the higher the power consumption, and the lower the efficiency, but the more complete the waveform and the better the linearity.

[0038] In the power amplifier structure, both the main amplifier 11 and the auxiliary amplifier 12 are active under saturation power, thereby improving efficiency by utilizing the auxiliary amplifier 12. Under back-off power, the auxiliary amplifier 12 is inactive, and the main amplifier 11 operates to improve linearity.

[0039] In some embodiments, the conduction angle of the main amplifier 11 may be greater than or equal to 180° and less than or equal to 360°, and the conduction angle of the auxiliary amplifier 12 may be less than 180°.

[0040] As an example, the main amplifier 11 can be configured as a Class B or Class AB amplifier, and the auxiliary amplifier 12 can be configured as a Class C amplifier. The specific gate voltages of the main amplifier 11 and the auxiliary amplifier 12 are set according to the subsequent turn-on operating point.

[0041] The secondary sides of multiple transformers 20 are connected in series to achieve power merging, while simultaneously distributing the load impedance to each power amplifier unit 10. The impedance matching network unit 30 adjusts the load impedance Z after the transformers 20 are connected in series. E =R opt The load impedance allocated to the primary side of each transformer is determined according to its respective turns ratio. The load impedance of each power amplifier unit 10 can be expressed as R. opt / N, where N is the number of channels in power amplifier unit 10.

[0042] In this embodiment, the impedance matching network unit 30 is configured to adjust the load impedance at the first end to the optimal load impedance corresponding to the main amplifier 11. In saturation power or back-off state, the impedance matching network unit 30, acting as a post-matching network, transforms the standard system impedance into R0. opt Traditional Doherty amplifiers require conversion of standard system impedance to R0 under back-off power conditions. opt / 2. In comparison, this implementation reduces the impedance transformation ratio to achieve bandwidth expansion.

[0043] As an example, the impedance matching network element 30 uses a characteristic impedance of sqrt(50*R). opt The λ / 4 impedance transformation line, R opt This is the optimal load impedance.

[0044] A load of 50Ω can use a standard system impedance, such as 50Ω, with a characteristic impedance of sqrt(50*R). opt The λ / 4 impedance transformation line converts 50Ω to R opt R is usually opt Less than 50Ω, thus achieving R opt Compared to achieving R, the transformation to 50Ω opt The transformation from Ω to 50Ω obviously has a smaller transformation ratio, which can expand the bandwidth.

[0045] For each power amplifier unit 10, its load impedance, after being distributed by transformer 20, can be Z. B =Z D =R opt / N. By setting the bias point of the auxiliary amplifier 12, the corresponding back-off power point can be set, thereby improving efficiency at back-off power and simultaneously improving efficiency at saturation power. For example, the power amplifier unit 10 can use a Doherty amplifier as described above.

[0046] Therefore, the load impedance of the impedance transformation unit 13 on the output side of each amplifier in the power amplifier structure of this application embodiment changes from R under back-off power. opt Starting from this point, compared to the aforementioned Doherty amplifier with R optStarting with / 2, a lower conversion ratio can be obtained, thus expanding the bandwidth.

[0047] In summary, the power amplifier structure proposed in this embodiment expands the bandwidth by reducing the impedance transformation ratio at both ends of the impedance transformation unit on the output side of the main amplifier in the backoff state, and also by reducing the impedance transformation ratio of the impedance matching network unit 30.

[0048] In some embodiments, the main amplifier 11 and the auxiliary amplifier 12 have the same transistor structure, the impedance ratio between the primary node of the transformer 20 and the secondary series node of each transformer 20 is 1:N, and the number of auxiliary amplifiers 12 is N-1.

[0049] The main amplifier 11 and the auxiliary amplifier 12 have identical transistor structures, meaning they have the same current capability. The input signal voltage V of the main amplifier 11 and the auxiliary amplifier 12... in =V max In this case, the main amplifier 11 and the auxiliary amplifier 12 have the same fundamental output current I. m Because of the symmetrical sampling of the amplifier, the load impedance distribution is advantageous, which helps to improve the overall efficiency.

[0050] The impedance ratio between the primary node of transformer 20 and the series-connected secondary nodes of each transformer is 1:N. The load impedance Z after transformer 20 is connected in series is... E =R opt In the case of transformer 20, the primary node Z B =Z D =R opt / N. The number of auxiliary amplifiers 12 is N-1, therefore the number of power paths in each power amplifier unit 10 is N-1+1 (the branch where the main amplifier 11 is located) = N. Thus, R opt / N*N=R opt This allows all amplifiers to operate at maximum efficiency.

[0051] As an example, Z B =Z C =R opt / 2, then the power amplifier unit 10 includes a main amplifier 11 and an auxiliary amplifier 12. Or Z B =Z C =R opt / 3, then the power amplifier unit 10 includes a main amplifier 11 and two auxiliary amplifiers 12.

[0052] In other embodiments, the current capabilities of the main amplifier 11 and the auxiliary amplifier 12 may also be different. For example, the current capability of the auxiliary amplifier 12 may be twice that of the main amplifier 11. This is reflected in the input signal voltage V of the main amplifier 11 and the auxiliary amplifier 12. in =V max In this case, the output current I of the main amplifier 11 m1 With the output current I of auxiliary amplifier 12 m2 Satisfy I m2 =2I m1 At this time in Z B =Z C =R opt In the case of / 3, the power amplifier unit 10 may also include a main amplifier 11 and an auxiliary amplifier 12.

[0053] In some embodiments, the turns ratios of each transformer 20 are the same.

[0054] The turns ratio of transformer 20 refers to the ratio of the number of turns in the primary winding to the number of turns in the secondary winding, i.e., K = N1 / N2, where N1 is the number of turns in the primary winding and N2 is the number of turns in the secondary winding. The turns ratio of transformer 20 also affects the impedance ratio between the primary and secondary windings, satisfying: Z1 = K² * Z2, where Z1 is the primary impedance and Z2 is the secondary impedance.

[0055] In this embodiment, the turns ratio of each transformer 20 is the same, so that the load impedance of the primary node of each transformer 20 is the same, and the power amplifier units 10 are symmetrical, which is conducive to the equal distribution of current and power and improves reliability.

[0056] In some embodiments, when the input signal voltage is less than or equal to V max When / k, the auxiliary amplifier 12 is turned off, and the impedance transformation unit 13 is configured to adjust the load impedance on the output side of the main amplifier 11 to f(x)N*R. opt And f(x)N / K≥1; where V max R is the maximum value of the input signal voltage when the amplifier is saturated. opt This is the optimal load impedance.

[0057] By configuring the bias point of the auxiliary amplifier 12, the turn-off voltage of the auxiliary amplifier 12 can be set to V. max / k. Input signal voltage greater than V max At / k, auxiliary amplifier 12 operates when the input signal voltage is less than or equal to V. max When / k, auxiliary amplifier 12 is turned off.

[0058] When auxiliary amplifier 12 is off, power amplifier 10 is in power back-off mode, operating only through main amplifier 11 to improve linearity. (The output signal is V...)max Taking / k as an example, the output current of the main amplifier 11 is I at this time. m / k, then the output voltage V1 = (I m / k)*(f(x)N*R opt Since f(x)N / K≥1, then V1≥I m *R opt This can improve output efficiency.

[0059] In some embodiments, the power amplifier unit further includes at least one phase compensation unit 14, each phase compensation unit being coupled between the input of each auxiliary amplifier 12 and the output of the corresponding power divider 40.

[0060] The impedance transformation unit 13 has a phase adjustment function, which allows the phase compensation unit 14 to be set in front of the auxiliary amplifier 12 to adjust the output response, making all outputs in phase, facilitating direct synthesis and power superposition through the transformer 20. The phase compensation unit 14 can be a λ / 4 phase compensation line.

[0061] Reference Figure 3 , Figure 3 This is a schematic diagram of the power amplifier structure provided in an embodiment of this application. In some embodiments, the power amplifier unit 10 has two channels, and there are two transformers 20, with a turns ratio of 1:1 for both transformers 20.

[0062] In this embodiment, the two transformers 20 with a turns ratio of 1:1 are paired with the load impedance Z. E =R opt Distribute the data to obtain Z. B =Z C =R opt / 2. The load impedances of the two power amplifier units 10 are symmetrical, and the use of a 1:1 transformer 20 can ensure that the current on both sides is equal, thereby improving reliability and efficiency.

[0063] In some embodiments, the power amplifier unit 10 includes a main amplifier 11 and an auxiliary amplifier 12, and the impedance transformation unit 13 adopts a characteristic impedance of R. opt λ / 4 impedance transformation line, R opt This is the optimal load impedance.

[0064] In this embodiment, the power amplifier unit 10 can adopt the Doherty structure as described above, which ensures efficiency in both high power saturation and back-off power states, and guarantees performance across the entire power range.

[0065] like Figure 3As shown, the power amplifier structure includes amplifiers PA1, PA2, PA3, and PA4, and two transformers 20, including T1 and T2. PA1 and PA3 are the main amplifiers 11, and PA2 and PA3 are the auxiliary amplifiers 12. PA1, PA2, PA3, and PA4 use the same power amplifier transistors, and the maximum input signal voltage at saturation is V. max When the input signal of each PA is lower than V max / 2, only PA1 and PA3 start working when the input signal of each PA is higher than V. max PA2 and PA4 only start working at / 2.

[0066] At the power back-off point, i.e., when the input signal of each PA is V... max When the impedance is 2 / 3, the load (Z=50Ω) passes through a segment with a characteristic impedance of sqrt(50*R). opt The λ / 4 impedance transformation line becomes Z. E =R opt The paths of PA1 and PA3 are completely symmetrical, outputting the same voltage and current. Furthermore, since both transformers have a 1:1 transformation ratio, Z... B =Z D =R opt / 2. Since PA2 and PA4 are not working at this time, their output impedances can be considered infinite, therefore Z A =Z C =R opt / 2. Also, since the characteristic impedance Z0 = R opt For the λ / 4 impedance transformation line, Z1=Z3=2R opt The output current of PA1 and PA3 at this time is I. m / 2, the output voltage is V1= I m* 2R opt =V m Therefore, at this point, the output voltages of PA1 and PA3 can reach their maximum amplitude, and the efficiency is the same as in the saturation state.

[0067] At the saturation point, that is, when the input signal of each PA is V... max At that time, the load (Z=50Ω) passes through a segment with a characteristic impedance of sqrt(50*R). opt The λ / 4 impedance transformation line becomes Z. E =R opt The paths of PA1 and PA3 are completely symmetrical, outputting the same voltage and current. Furthermore, since both transformers have a 1:1 transformation ratio, Z... B =Z D =R opt / 2. Due to the load modulation effect, Z A =Z C =Ropt Then, through the characteristic impedance Z0=R opt For the λ / 4 impedance transformation line, Z1=Z3=R opt At this point, the output voltage and current of PA1 and PA3 both reach their maximum, and the load impedance is also at its optimal impedance R. opt At this point, the efficiency of PA1 and PA3 reaches its maximum. Simultaneously, the load impedances Z2 and Z4 of PA2 and PA4 also reach R due to the load modulation effect. opt This means that PA2 and PA4 are both operating at their optimal efficiency.

[0068] Therefore, through the voltage synthesis of the two transformers 20, Z... E =2Z B =2Z D Because the impedance of an RF power amplifier is generally low during operation, Z E Doubling the impedance is beneficial for impedance matching network unit 30. When the impedance is converted to a common 50 ohms, the impedance transformation ratio is reduced, thereby expanding the bandwidth. The parallel structure of 4 PAs also increases the power capacity.

[0069] Reference Figure 4 , Figure 4 This is a graph showing the overall efficiency of the power amplifier structure provided in this application embodiment as a function of the input voltage. Figure 4 In the diagram, m3 is the power-back point and m4 is the saturation point. It can be seen that the power amplifier structure provided in this embodiment has basically the same efficiency at the power-back point and the saturation point.

[0070] Reference Figure 5 , Figure 5 The diagram shows the trend of the load impedance of the main amplifier in the power amplifier structure provided in this application embodiment. From... Figure 5 As can be seen from this, in the power back-off state, the normalized impedance of the main amplifier 11 reaches 2R. opt This improves efficiency in the backoff state. In saturation, the normalized impedance of the main amplifier 11 reaches R0. opt This ensures that the efficiency at the backoff power point and the saturation point is the same.

[0071] Reference Figure 6 and Figure 7 , Figure 6 This is a comparison chart of the bandwidth characteristics of the normalized load impedance real part of the power amplifier structure. Figure 7 This is a comparison diagram of the bandwidth characteristics of the imaginary part of the load impedance of the power amplifier structure. As shown in Figure 6, curve a represents the bandwidth characteristics of the normalized real part of the load impedance of the traditional Doherty structure, while curve b represents the bandwidth characteristics of the proposed structure in this application. Figure 3The diagram shows the bandwidth characteristics of the normalized real part of the load impedance of the power amplifier structure. Curve c represents the bandwidth characteristics of the real part of the load impedance of the traditional Doherty structure, and curve d represents the bandwidth characteristics of the proposed structure in this application. Figure 3 The bandwidth characteristics of the real part of the load impedance of the power amplifier structure shown are illustrated.

[0072] As can be seen from the figure above, the power amplifier structure proposed in this application has better bandwidth characteristics and expands the bandwidth compared with the traditional Doherty structure.

[0073] One embodiment of this application also provides a communication device, which includes the power amplifier structure according to the foregoing.

[0074] The specific structure and principle of the power amplifier can be referred to in the foregoing embodiments. Communication devices including power amplifier structures can adopt the technical solutions of the above embodiments and also have the corresponding technical effects.

[0075] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0076] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A power amplifier structure, characterized by, include: A multi-channel power amplifier unit, each of the power amplifier units including a main amplifier, at least one auxiliary amplifier and an impedance transformation unit, wherein the output of the main amplifier is coupled in parallel with the output of each of the auxiliary amplifiers through the impedance transformation unit; Multiple transformers, the primary side of each transformer is coupled to the parallel coupling node of each power amplifier unit, and the secondary side of each transformer is connected in series; An impedance matching network unit is provided, wherein a first end of the impedance matching network unit is coupled in series with the secondary side of each of the transformers, and a second end of the impedance matching network unit is coupled with the load. The impedance matching network unit is configured to adjust the load impedance of the second end so that the first end has the optimal load impedance corresponding to the main amplifier. A power divider, the output of which is coupled to the inputs of the main amplifier and the auxiliary amplifier in each of the power amplifier units.

2. The power amplifier structure of claim 1, wherein, The main amplifier and the auxiliary amplifier have the same transistor structure. The impedance ratio between the primary node of the transformer and the series node of the secondary side of each transformer is 1:N. The number of auxiliary amplifiers is N-1.

3. The power amplifier structure of claim 2, wherein, All the transformers have the same turns ratio.

4. The power amplifier structure of claim 2, wherein, When the input signal voltage is less than or equal to V max When / k, the auxiliary amplifier is turned off, and the impedance transformation unit is configured to adjust the load impedance on the output side of the main amplifier to f(x)N*R. opt And f(x)N / K≥1; where V max is the maximum input signal voltage at which the amplifier saturates, R opt is the optimal load impedance.

5. The power amplifier structure according to claim 1, characterized in that, The power amplifier unit has two channels, and there are two transformers, both with a turns ratio of 1:

1.

6. The power amplifier structure of claim 5, wherein, The power amplifier unit comprises a main amplifier and an auxiliary amplifier, and the impedance conversion unit adopts a λ / 4 impedance conversion line with a characteristic impedance R opt , and R opt is the optimal load impedance.

7. The power amplifier structure of any of claims 1-6, wherein, The impedance matching network unit adopts a characteristic impedance of sqrt(50*R). opt The λ / 4 impedance transformation line, R opt The optimal load impedance is given.

8. The power amplifier structure of any of claims 1-6, wherein, The conduction angle of the main amplifier is greater than or equal to 180° and less than or equal to 360°, and the conduction angle of the auxiliary amplifier is less than 180°.

9. The power amplifier structure of any of claims 1-6, wherein, The power amplifier unit also includes: At least one phase compensation unit, each of the phase compensation units being coupled between the input of each of the auxiliary amplifiers and the corresponding output of the power divider.

10. A communication device, comprising: The communication device includes a power amplifier structure according to any one of claims 1-9.

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