A voltage synthesis type Doherty power amplifier

Abstract

The present invention provides a voltage synthesis type Doherty power amplifier, which comprises an adaptive input power divider, a power amplifier network and a voltage synthesis type power combining network; the adaptive input power divider includes a first capacitor, a second capacitor and a first inductor; the power amplifier network includes a first phase compensation network, a first input matching network, a carrier power amplifier, a second phase compensation network, a second input matching network, a peak power amplifier and an impedance inversion network; the voltage synthesis type power combining network includes a balun transformer unit and a port impedance transformation network. The voltage synthesis type Doherty power amplifier of the present invention has self-distribution of input power for power amplification, high efficiency and high linearity of output power.

Description

Technical Field

[0001] The present invention relates to the field of circuit technologies, and particularly to a voltage-combined Doherty power amplifier. Background Art

[0002] At present, a radio frequency power amplifier has a specific optimal load impedance. With a fixed load, the maximum output voltage and current swing are only achieved at the peak output power, and the efficiency is maximized at the peak power point. The efficiency decreases rapidly during power back-off. The Doherty technique is based on load modulation at the output end. The size of the output load is determined by the current ratio between the carrier power amplifier and the peak power amplifier. The load impedance is dynamically adjusted. According to the size of the modulated load impedance value, the maximum efficiency can be achieved at different power points, which is an optimal solution for amplifying signals with a high peak-to-average ratio. Therefore, the Doherty structure is a commonly used method in the design of radio frequency power amplifiers.

[0003] The related-art Doherty power amplifiers generally adopt a current-combined structure and a voltage-combined structure. Among them, the Doherty power amplifier adopting the current-combined structure is formed by connecting two amplifiers, namely a carrier power amplifier and a peak power amplifier, in parallel. The carrier power amplifier operates in class AB, and the peak power amplifier operates in class C. The load impedance matching network transforms the load Z L to R opt / 2 (R opt is the optimal output impedance when the output powers of the carrier power amplifier and the peak power amplifier are the largest). When the input power is small, the Doherty power amplifier operates in the low-power mode, the peak power amplifier is not turned on, and only the carrier power amplifier operates. The load impedance at its output end is 2R opt . As the input power increases, when the output power of the carrier power amplifier approaches the saturation power, the efficiency of the carrier power amplifier reaches the first peak point. At the same time, the peak power amplifier is turned on, and both the carrier power amplifier and the peak power amplifier operate. The Doherty power amplifier enters the high-power mode. The output power is the power obtained by combining the output powers of the carrier power amplifier and the peak power amplifier. The load impedance of the carrier power amplifier gradually transforms from 2R opt to R opt , and the load impedance of the peak power amplifier gradually transforms from infinity to R opt . Ideally, when the Doherty power amplifier operates in the high-power mode, its maximum output power increases by ~6 dB compared with the maximum output power in the low-power mode. In addition, the Doherty power amplifier adopting the voltage-combined structure is formed by connecting two amplifiers, namely a carrier power amplifier and a peak power amplifier, in parallel. The load impedance transformation network transforms the load Z L to Z L ’ = 2R optLoad modulation is achieved through a quarter-wavelength transmission line at the output end of the peak power amplifier. When the input power is small, the Doherty power amplifier operates in the low-power mode, the peak power amplifier is turned off, and the output impedance is infinite. After being transformed by the quarter-wavelength transmission line, the impedance is transformed to zero ohms, and the load impedance at the output end of the carrier power amplifier is 2R opt As the input power increases, the peak power amplifier is turned on, and the carrier power amplifier and the peak power amplifier work simultaneously. The Doherty power amplifier enters the high-power mode, and the load impedance of the carrier power amplifier changes from 2R opt gradually to R opt , and the load impedance of the peak power amplifier changes from infinity to R opt . The outputs of the carrier power amplifier and the peak power amplifier are superimposed in output voltage and synthesized in power through a transformer. Compared with the load impedance Z of the traditional current-combining Doherty power amplifier L which needs to change from 50 ohms to R opt , the voltage-combining Doherty power amplifier only needs to change from 50 ohms to 2R opt , reducing the impedance transformation ratio and increasing the bandwidth. At the same time, in the low-output-power region, since the carrier power amplifier of the voltage-combining Doherty power amplifier is directly connected to the load and does not require a quarter-wavelength impedance inversion, good impedance matching can be achieved within a wider frequency band range.

[0004] However, in the Doherty power amplifier of the related technology, the peak power amplifier is biased in class C, and the carrier power amplifier is biased in class AB. The power gain of the peak power amplifier is lower than that of the carrier power amplifier. When the Doherty power amplifier operates in the high-output-power mode, the load of the peak power amplifier is not modulated to a low enough level, resulting in a small maximum output power. The load impedances of the carrier power amplifier and the peak power amplifier cannot be fully modulated, and the output power after the synthesis of the carrier power amplifier and the peak power amplifier is reduced compared with that when the load is fully modulated, and the amplitude-amplitude modulation (AM-AM) characteristic also deteriorates. Moreover, due to the soft-switching characteristic of the peak power amplifier, when the power is back-off, the load faced by the carrier power amplifier is pulled down earlier, and the efficiency is also reduced. At the same time, since neither the carrier power amplifier nor the peak power amplifier reaches the ideal output power state, the third-order intermodulation terms of the carrier power amplifier and the peak power amplifier cannot achieve ideal cancellation, and the linearity of the Doherty power amplifier also deteriorates.

[0005] Therefore, it is necessary to provide a new voltage-combining Doherty power amplifier to solve the above problems. Summary of the Invention

[0006] Aiming at the above deficiencies of the prior art, the present invention proposes a new voltage-combining Doherty power amplifier with self-distribution of input power.

[0007] To solve the above technical problems, an embodiment of the present invention provides a voltage synthesis type Doherty power amplifier. The voltage synthesis type Doherty power amplifier includes an adaptive input power divider, a power amplifier network, and a voltage synthesis type power combining network;

[0008] The adaptive input power divider includes a first capacitor, a second capacitor, and a first inductor;

[0009] The power amplifier network includes a first phase compensation network, a first input matching network, a carrier power amplifier, a second phase compensation network, a second input matching network, a peak power amplifier, and an impedance inversion network; the first phase compensation network is used to connect an input signal and phase-shift the input signal, the first input matching network is used to achieve input impedance matching, the carrier power amplifier is used to amplify the power of the signal, the second phase compensation network is used to phase-shift the input signal, the second input matching network is used to achieve input impedance matching, the peak power amplifier is used to amplify the power of the signal, and the impedance inversion network is used to invert the input impedance;

[0010] The voltage synthesis type power combining network includes a balun transformer unit and a port impedance transformation network, and the port impedance transformation network is used to achieve output impedance matching;

[0011] The first end of the first capacitor serves as the input end of the voltage synthesis type Doherty power amplifier, and the first end of the first capacitor is respectively connected to the first end of the first inductor and the input end of the first phase compensation network; the second end of the first capacitor is grounded;

[0012] The output end of the first phase compensation network is connected to the input end of the first input matching network, the output end of the first input matching network is connected to the input end of the carrier power amplifier, the output end of the carrier power amplifier is connected to the input end of the second phase compensation network, and the output end of the second phase compensation network is connected to the first end of the primary coil of the balun transformer unit;

[0013] The second end of the first inductor is respectively connected to the first end of the second capacitor and the input end of the second input matching network; the second end of the second capacitor is grounded;

[0014] The output end of the second input matching network is connected to the input end of the peak power amplifier, the output end of the peak power amplifier is connected to the input end of the impedance inversion network, and the output end of the impedance inversion network is connected to the second end of the primary coil of the balun transformer unit;

[0015] The first end of the secondary coil of the balun transformer unit is connected to the input end of the port impedance transformation network, and the second end of the secondary coil of the balun transformer unit is grounded;

[0016] The output end of the port impedance transformation network serves as the output end of the voltage-combined Doherty power amplifier.

[0017] Preferably, the carrier power amplifier includes a first transformer, a third capacitor, a fourth capacitor, a first power amplifier, a third power amplifier, and a fourth power amplifier;

[0018] The output end of the carrier power amplifier includes two parts, namely the first output end of the carrier power amplifier and the second output end of the carrier power amplifier;

[0019] The input end of the first power amplifier serves as the input end of the carrier power amplifier, and the output end of the first power amplifier is connected to the first end of the primary coil of the first transformer;

[0020] The second end of the primary coil of the first transformer is grounded, and the center-tapped end of the primary coil of the first transformer is connected to the power supply voltage;

[0021] The first end of the secondary coil of the first transformer is respectively connected to the input end of the third power amplifier and the first end of the fourth capacitor;

[0022] The second end of the secondary coil of the first transformer is respectively connected to the input end of the fourth power amplifier and the second end of the fourth capacitor;

[0023] The center-tapped end of the secondary coil of the first transformer is connected to the first end of the third capacitor; the second end of the third capacitor is grounded;

[0024] The output end of the third power amplifier serves as the first output end of the carrier power amplifier;

[0025] The output end of the fourth power amplifier serves as the second output end of the carrier power amplifier.

[0026] Preferably, the second phase compensation network includes a seventh capacitor, an eighth capacitor, a first reactance element, and a second reactance element, and both the first reactance element and the second reactance element are used to adjust the circuit passband;

[0027] The input end of the second phase compensation network includes two, namely the first input end and the second input end of the second phase compensation network respectively; the output end of the second phase compensation network includes two, namely the first output end and the second output end of the second phase compensation network respectively;

[0028] The first end of the seventh capacitor serves as the first input end of the second phase compensation network, and the first end of the seventh capacitor is connected to the first end of the first reactance element;

[0029] The second end of the first reactance element serves as the first output end of the second phase compensation network, and the second end of the first reactance element is connected to the first end of the eighth capacitor;

[0030] The second end of the seventh capacitor serves as the second input end of the second phase compensation network, and the second end of the seventh capacitor is connected to the first end of the second reactance element;

[0031] The second end of the second reactance element serves as the second output end of the second phase compensation network, and the second end of the second reactance element is connected to the second end of the eighth capacitor.

[0032] Preferably, the peak power amplifier includes a second transformer, a fifth capacitor, a sixth capacitor, a second power amplifier, a fifth power amplifier, and a sixth power amplifier;

[0033] The output end of the peak power amplifier includes two, namely the first output end and the second output end of the peak power amplifier respectively;

[0034] The input end of the second power amplifier serves as the input end of the peak power amplifier, and the output end of the second power amplifier is connected to the first end of the primary coil of the second transformer;

[0035] The second end of the primary coil of the second transformer is grounded, and the center tap end of the primary coil of the second transformer is connected to the power supply voltage;

[0036] The first end of the secondary coil of the second transformer is respectively connected to the input end of the fifth power amplifier and the first end of the sixth capacitor;

[0037] The second end of the secondary coil of the second transformer is respectively connected to the input end of the sixth power amplifier and the second end of the sixth capacitor;

[0038] The center tap end of the secondary coil of the second transformer is connected to the first end of the fifth capacitor; the second end of the third capacitor is grounded;

[0039] The output terminal of the fifth power amplifier serves as the first output terminal of the peak power amplifier;

[0040] The output terminal of the sixth power amplifier serves as the second output terminal of the peak power amplifier.

[0041] Preferably, the impedance inversion network includes a ninth capacitor, a tenth capacitor, a second inductor, a third inductor, a third reactance element, and a fourth reactance element, and both the third reactance element and the fourth reactance element are used to adjust the circuit passband;

[0042] The input terminal of the impedance inversion network includes two, namely the first input terminal and the second input terminal of the impedance inversion network respectively; the output terminal of the impedance inversion network includes two, namely the first output terminal and the second output terminal of the impedance inversion network respectively;

[0043] The first end of the ninth capacitor serves as the first input terminal of the impedance inversion network, and the first end of the ninth capacitor is connected to the first end of the third reactance element;

[0044] The second end of the third reactance element is connected to the first end of the second inductor;

[0045] The second end of the second inductor serves as the first output terminal of the impedance inversion network, and the second end of the second inductor is connected to the first end of the tenth capacitor;

[0046] The second end of the ninth capacitor serves as the second input terminal of the impedance inversion network, and the second end of the ninth capacitor is connected to the first end of the fourth reactance element;

[0047] The second end of the fourth reactance element is connected to the first end of the third inductor;

[0048] The second end of the third inductor serves as the second output terminal of the impedance inversion network, and the second end of the third inductor is connected to the second end of the tenth capacitor.

[0049] Preferably, the balun transformer unit includes a third transformer and a fourth transformer;

[0050] The first end of the primary coil of the balun transformer unit includes two, namely the first end and the second end of the primary coil of the third transformer respectively;

[0051] The center tap of the primary coil of the third transformer is connected to the power supply voltage;

[0052] The first end of the secondary coil of the third transformer serves as the first end of the secondary coil of the balun transformer unit;

[0053] The second end of the secondary coil of the third transformer is connected to the first end of the secondary coil of the fourth transformer;

[0054] The second end of the primary coil of the balun transformer unit includes two parts, which are respectively the first end of the primary coil of the fourth transformer and the second end of the primary coil of the fourth transformer;

[0055] The center-tapped end of the primary coil of the fourth transformer is connected to the power supply voltage;

[0056] The second end of the secondary coil of the fourth transformer serves as the second end of the secondary coil of the balun transformer unit, and the second end of the secondary coil of the fourth transformer is grounded.

[0057] Preferably, the port impedance transformation network is an eleventh capacitor, and the first end of the eleventh capacitor serves as the input end of the port impedance transformation network; the first end of the eleventh capacitor is grounded.

[0058] Preferably, the circuit structures of the carrier power amplifier and the peak power amplifier are the same, and each component included in the carrier power amplifier corresponds one by one to each component included in the peak power amplifier, and the performance and size of the components are the same.

[0059] Preferably, the optimal impedance of the carrier power amplifier and the optimal impedance of the peak power amplifier are both R opt ;

[0060] When the voltage-combined Doherty power amplifier operates in the low-power operating mode, the load impedance of the secondary coil of the balun transformer unit is Z L ’, and it satisfies: Z L ’ = 2R opt , the load impedance of the carrier power amplifier is Z Carrier , and it satisfies: Z Carrier = 2R opt ;

[0061] When the voltage-combined Doherty power amplifier operates in the high-power operating mode, the load impedance of the peak power amplifier is Z peaking , and it satisfies: Z peaking = R opt .

[0062] Preferably, the first power amplifier, the second power amplifier, the third power amplifier, the fourth power amplifier, the fifth power amplifier, and the sixth power amplifier are all implemented by transistors.

[0063] Compared with the related art, the voltage synthesis type Doherty power amplifier of the present invention includes an adaptive input power divider, a power amplifier network, and a voltage synthesis type power combining network. Among them, the adaptive input power divider includes a first capacitor, a second capacitor, and a first inductor; the power amplifier network includes a first phase compensation network, a first input matching network, a carrier power amplifier, a second phase compensation network, a second input matching network, a peak power amplifier, and an impedance inversion network; when the voltage synthesis type Doherty power amplifier operates in the low power mode, the input power is in the low input power range, the peak power amplifier is turned off, and most of the input power is input into the carrier power amplifier; when the voltage synthesis type Doherty power amplifier operates in the high power mode, the input power is in the high input power range, the carrier power amplifier enters the saturation amplification state, and most of the input power is input into the peak power amplifier, improving the gain of the peak power amplifier. This circuit enables the voltage synthesis type Doherty power amplifier of the present invention to dynamically control the power input to the carrier power amplifier and the peak power amplifier in the power amplifier network, and control the power flowing into the carrier power amplifier and the peak power amplifier according to the magnitude of the input power, so that the power amplification efficiency of the voltage synthesis type Doherty power amplifier of the present invention is high. In addition, the adaptive input power divider with variable power distribution ratio realizes the functions of input power self-distribution and predistortion, linearizing the output power of the voltage synthesis type Doherty power amplifier. Brief Description of the Drawings

[0064] The present invention will be described in detail below with reference to the drawings. Through the detailed description in combination with the following drawings, the above or other aspects of the present invention will become clearer and easier to understand. In the drawings,

[0065] Figure 1 is a schematic circuit structure diagram of the voltage synthesis type Doherty power amplifier of the present invention;

[0066] Figure 2 is a schematic application circuit structure diagram of the voltage synthesis type Doherty power amplifier of the present invention;

[0067] Figure 3 is a schematic circuit diagram of the voltage synthesis type Doherty power amplifier of the present invention;

[0068] Figure 4Schematic diagram of the adaptive input power divider of the voltage synthesis type Doherty power amplifier provided by the embodiments of the present invention. Detailed implementation manners

[0069] The following will describe in detail the specific implementation manners of the present invention with reference to the accompanying drawings.

[0070] The specific implementation manners / embodiments recorded herein are specific specific implementation manners of the present invention, used to illustrate the concept of the present invention, and are all explanatory and exemplary, and should not be construed as a limitation on the implementation manners of the present invention and the scope of the present invention. Except for the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments recorded herein, and are all within the protection scope of the present invention.

[0071] Embodiments of the present invention provide a voltage synthesis type Doherty power amplifier 100.

[0072] Please refer to Figure 1-2 as shown Figure 1 which is a schematic diagram of the circuit structure of the voltage synthesis type Doherty power amplifier 100 of the present invention; Figure 2 which is a schematic diagram of the application circuit structure of the voltage synthesis type Doherty power amplifier 100 of the present invention.

[0073] The voltage synthesis type Doherty power amplifier 100 includes an adaptive input power divider 1, a power amplifier network 2, and a voltage synthesis type power combining network 3.

[0074] The adaptive input power divider 1 includes a first capacitor C1, a second capacitor C2, and a first inductor L1.

[0075] The voltage synthesis type Doherty power amplifier 100 realizes the pre-distortion function through the adaptive input power divider 1 with a variable power distribution ratio, and linearizes the output power of the voltage synthesis type Doherty power amplifier 100.

[0076] The power amplifier network 2 includes a first phase compensation network 21, a first input matching network 22, a carrier power amplifier 23, a second phase compensation network 24, a second input matching network 25, a peak power amplifier 26, and an impedance inversion network 27. Among them, the first phase compensation network 21 is used to phase-shift the input signal. The first input matching network 22 is used for input impedance matching. The carrier power amplifier 23 is used for signal amplification. The second phase compensation network 24 is used to phase-shift the input signal, and the second input matching network 25 is used for input impedance matching. The peak power amplifier 26 is used for signal amplification. The impedance inversion network 27 is used to invert the input impedance.

[0077] The voltage synthesis type power combining network 3 includes a balun transformer unit 31 and a port impedance transformation network 32.

[0078] The port impedance transformation network 32 is used for output impedance matching.

[0079] The circuit connection relationship of the voltage synthesis type Doherty power amplifier 100 is as follows: The first end of the first capacitor C1 serves as the input terminal RFin of the voltage synthesis type Doherty power amplifier 100, and the first end of the first capacitor C1 is respectively connected to the first end of the first inductor L1 and the input end of the first phase compensation network 21. The second end of the first capacitor C1 is grounded to GND.

[0080] The output end of the first phase compensation network 21 is connected to the input end of the first input matching network 22, the output end of the first input matching network 22 is connected to the input end of the carrier power amplifier 23, the output end of the carrier power amplifier 23 is connected to the input end of the second phase compensation network 24, and the output end of the second phase compensation network 24 is connected to the first end of the primary coil LP1 of the balun transformer unit 31.

[0081] The second end of the first inductor L1 is respectively connected to the first end of the second capacitor C2 and the input end of the second input matching network 25. The second end of the second capacitor C2 is grounded to GND.

[0082] The output end of the second input matching network 25 is connected to the input end of the peak power amplifier 26, the output end of the peak power amplifier 26 is connected to the input end of the impedance inversion network 27, and the output end of the impedance inversion network 27 is connected to the second end of the primary coil LP1 of the balun transformer unit 31.

[0083] A first end of the secondary coil LS1 of the balun transformer unit 31 is connected to the input end of the port impedance conversion network 32 , and a second end of the secondary coil LS1 of the balun transformer unit 31 is grounded GND.

[0084] The output end of the port impedance conversion network 32 serves as the output end RFout of the voltage synthesis Doherty power amplifier 100 .

[0085] The output terminal RFout of the voltage synthesis Doherty power amplifier 100 is used to connect to an external load R L .

[0086] This circuit enables the voltage-synthesized Doherty power amplifier of the present invention to dynamically control the power input to the carrier power amplifier 23 and the peak power amplifier 26 of the power amplifier network 2, and controls the power flowing into the carrier power amplifier 23 and the peak power amplifier 26 according to the size of the input power, thereby making the power amplification efficiency of the voltage-synthesized Doherty power amplifier 100 of the present invention high.

[0087] Please refer to Figure 3 As shown, Figure 3 FIG. 1 is a circuit diagram of a voltage synthesis Doherty power amplifier 100 according to the present invention.

[0088] The first phase compensation network 21, the first input matching network 22 and the second input matching network 25 all adopt module circuits commonly used in the art, and their circuit forms and performances are selected and determined according to actual design requirements, and are not described in detail here.

[0089] The carrier power amplifier 23 includes a first transformer XFM1 , a third capacitor C3 , a fourth capacitor C4 , a first power amplifier PA1 , a third power amplifier PA3 , and a fourth power amplifier PA4 .

[0090] The carrier power amplifier 23 includes two output terminals, namely a first output terminal of the carrier power amplifier 23 and a second output terminal of the carrier power amplifier 23 .

[0091] The internal circuit connection relationship of the carrier power amplifier 23 is:

[0092] An input end of the first power amplifier PA1 serves as an input end of the carrier power amplifier 23 , and an output end of the first power amplifier PA1 is connected to a first end of the primary coil LP2 of the first transformer XFM1 .

[0093] The second end of the primary coil LP2 of the first transformer XFM1 is grounded to GND, and the center-tapped end of the primary coil LP2 of the first transformer XFM1 is connected to the power supply voltage VCC.

[0094] The first end of the secondary coil LS2 of the first transformer XFM1 is respectively connected to the input end of the third power amplifier PA3 and the first end of the fourth capacitor C4.

[0095] The second end of the secondary coil LS2 of the first transformer XFM1 is respectively connected to the input end of the fourth power amplifier PA4 and the second end of the fourth capacitor C4.

[0096] The center-tapped end of the secondary coil LS2 of the first transformer XFM1 is connected to the first end of the third capacitor C3. The second end of the third capacitor C3 is grounded to GND.

[0097] The output end of the third power amplifier PA3 serves as the first output end of the carrier power amplifier 23.

[0098] The output end of the fourth power amplifier PA4 serves as the second output end of the carrier power amplifier 23.

[0099] In this embodiment, the second phase compensation network 24 includes a seventh capacitor C7, an eighth capacitor C8, a first reactance element BW1, and a second reactance element BW2.

[0100] Both the first reactance element BW1 and the second reactance element BW2 are used to adjust the circuit passband, and both the first reactance element BW1 and the second reactance element BW2 are reactance elements. The passband is generated due to the reactance elements (capacitors and inductors) existing in the amplifier circuit. Since reactance (capacitive reactance and inductive reactance) is a function of frequency and changes with frequency. For example, for an emitter bypass capacitor, the capacitive reactance to the signal is greater when the signal frequency is lower, while for an inductor, the inductive reactance is greater when the signal frequency is higher. When the frequency drops to a certain value, the capacitive reactance in the circuit will cause obvious attenuation to the signal at this frequency and below. Conversely, when the frequency rises to a certain value, the inductive reactance in the circuit will also cause obvious attenuation to the signal at this frequency and above. The frequency range between this lower and higher frequency value is the passband. Within the passband, the reactance in the circuit causes less attenuation to the signal and can basically be ignored.

[0101] The internal circuit connection relationship of the second phase compensation network 24 is as follows:

[0102] The input end of the second phase compensation network 24 includes two parts, namely the first input end of the second phase compensation network 24 and the second input end of the second phase compensation network 24. The output end of the second phase compensation network 24 includes two parts, namely the first output end of the second phase compensation network 24 and the second output end of the second phase compensation network 24.

[0103] The first end of the seventh capacitor C7 serves as the first input end of the second phase compensation network 24, and the first end of the seventh capacitor C7 is connected to the first end of the first reactance element BW1.

[0104] The second end of the first reactance element BW1 serves as the first output end of the second phase compensation network 24, and the second end of the first reactance element BW1 is connected to the first end of the eighth capacitor C8.

[0105] The second end of the seventh capacitor C7 serves as the second input end of the second phase compensation network 24, and the second end of the seventh capacitor C7 is connected to the first end of the second reactance element BW2.

[0106] The second end of the second reactance element BW2 serves as the second output end of the second phase compensation network 24, and the second end of the second reactance element BW2 is connected to the second end of the eighth capacitor C8.

[0107] In this embodiment, the peak power amplifier 26 includes a second transformer XFM2, a fifth capacitor C5, a sixth capacitor C6, a second power amplifier PA2, a fifth power amplifier PA5, and a sixth power amplifier PA6.

[0108] In this embodiment, the first power amplifier PA1, the second power amplifier PA2, the third power amplifier PA3, the fourth power amplifier PA4, the fifth power amplifier PA5, and the sixth power amplifier PA6 are all transistor amplifier circuits, which can be realized by integrated circuit technology, facilitating integration and being suitable for radio frequency integrated circuits.

[0109] The internal circuit connection relationship of the peak power amplifier 26 is as follows:

[0110] The output end of the peak power amplifier 26 includes two parts, namely the first output end of the peak power amplifier 26 and the second output end of the peak power amplifier 26.

[0111] The input end of the second power amplifier PA2 serves as the input end of the peak power amplifier 26, and the output end of the second power amplifier PA2 is connected to the first end of the primary coil LP3 of the second transformer XFM2.

[0112] The second end of the primary coil LP3 of the second transformer XFM2 is grounded to GND, and the center-tapped end of the primary coil LP3 of the second transformer XFM2 is connected to the power supply voltage VCC.

[0113] The first end of the secondary coil LS3 of the second transformer XFM2 is respectively connected to the input end of the fifth power amplifier PA5 and the first end of the sixth capacitor C6.

[0114] The second end of the secondary coil LS3 of the second transformer XFM2 is respectively connected to the input end of the sixth power amplifier PA6 and the second end of the sixth capacitor C6.

[0115] The center-tapped end of the secondary coil LS3 of the second transformer XFM2 is connected to the first end of the fifth capacitor C5. The second end of the third capacitor C3 is grounded to GND.

[0116] The output end of the fifth power amplifier PA5 serves as the first output end of the peak power amplifier 26.

[0117] The output end of the sixth power amplifier PA6 serves as the second output end of the peak power amplifier 26.

[0118] In this embodiment, the circuit structures of the carrier power amplifier 23 and the peak power amplifier 26 are the same. Each component included in the carrier power amplifier 23 corresponds one-to-one to each component included in the peak power amplifier 26, and the performance and size of the components are the same. This circuit structure is beneficial to integration and is applicable to radio frequency integrated circuits.

[0119] In this embodiment, the impedance inversion network 27 includes a ninth capacitor C9, a tenth capacitor C10, a second inductor L2, a third inductor L3, a third reactance element BW3, and a fourth reactance element BW4. Both the third reactance element BW3 and the fourth reactance element BW4 are used to adjust the circuit passband. Both the third reactance element BW3 and the fourth reactance element BW4 are reactance elements.

[0120] The input end of the impedance inversion network 27 includes two, namely the first input end and the second input end of the impedance inversion network 27 respectively. The output end of the impedance inversion network 27 includes two, namely the first output end and the second output end of the impedance inversion network 27 respectively.

[0121] The internal circuit connection relationship of the impedance inversion network 27 is as follows:

[0122] The first terminal of the ninth capacitor C9 serves as the first input terminal of the impedance inversion network 27, and the first terminal of the ninth capacitor C9 is connected to the first terminal of the third reactance element BW3.

[0123] The second terminal of the third reactance element BW3 is connected to the first terminal of the second inductor L2.

[0124] The second terminal of the second inductor L2 serves as the first output terminal of the impedance inversion network 27, and the second terminal of the second inductor L2 is connected to the first terminal of the tenth capacitor C10.

[0125] The second terminal of the ninth capacitor C9 serves as the second input terminal of the impedance inversion network 27, and the second terminal of the ninth capacitor C9 is connected to the first terminal of the fourth reactance element BW4.

[0126] The second terminal of the fourth reactance element BW4 is connected to the first terminal of the third inductor L3.

[0127] The second terminal of the third inductor L3 serves as the second output terminal of the impedance inversion network 27, and the second terminal of the third inductor L3 is connected to the second terminal of the tenth capacitor C10.

[0128] In this embodiment, the balun transformer unit 31 includes a third transformer XFM3 and a fourth transformer XFM4.

[0129] The first terminal of the primary coil LP1 of the balun transformer unit 31 includes two parts, which are respectively the first terminal and the second terminal of the primary coil LP4 of the third transformer XFM3.

[0130] The internal circuit connection relationship of the balun transformer unit 31 is as follows:

[0131] The center-tapped terminal of the primary coil LP4 of the third transformer XFM3 is connected to the power supply voltage VCC.

[0132] The first terminal of the secondary coil LS4 of the third transformer XFM3 serves as the first terminal of the secondary coil LS1 of the balun transformer unit 31.

[0133] The second terminal of the secondary coil LS4 of the third transformer XFM3 is connected to the first terminal of the secondary coil LS5 of the fourth transformer XFM4.

[0134] The second terminal of the primary coil LP1 of the balun transformer unit 31 includes two parts, which are respectively the first terminal and the second terminal of the primary coil LP5 of the fourth transformer XFM4.

[0135] The center tap of the primary coil LP5 of the fourth transformer XFM4 is connected to the power supply voltage VCC.

[0136] The second end of the secondary coil LS5 of the fourth transformer XFM4 serves as the second end of the secondary coil LS1 of the balun transformer unit 31, and the second end of the secondary coil LS5 of the fourth transformer XFM4 is grounded to GND.

[0137] In this embodiment, the port impedance transformation network 32 is the eleventh capacitor C11. The first end of the eleventh capacitor C11 serves as the input end of the port impedance transformation network 32. The first end of the eleventh capacitor C11 is grounded to GND. This circuit structure uses the eleventh capacitor C11 for impedance transformation, making the circuit structure simple.

[0138] The working principle of the voltage-combined Doherty power amplifier 100 is as follows:

[0139] In this embodiment, the optimal impedance of the carrier power amplifier 23 and the optimal impedance of the peak power amplifier 26 are both R opt .

[0140] When the voltage-combined Doherty power amplifier 100 works in the low-power working mode, the load impedance of the secondary coil LS1 of the balun transformer unit 31 is Z L ’, and it satisfies: Z L ’ = 2R opt , and the load impedance of the carrier power amplifier 23 is Z Carrier , and it satisfies: Z Carrier = 2R opt .

[0141] When the voltage-combined Doherty power amplifier 100 works in the high-power working mode, the load impedance of the peak power amplifier 26 is Z peaking , and it satisfies: Z peaking = R opt .

[0142] The input signal RFin completes the proportional distribution of the input power through the adaptive input power distributor 1 composed of the first capacitor C1, the second capacitor C2, and the first inductor L1. The carrier power amplifier 23 and the peak power amplifier 26 have the same size, and the optimal impedance is R opt. In the low-power operating mode, only the carrier power amplifier 23 is operational, and the peak power amplifier 26 is turned off. The output impedance of the peak power amplifier 26 is infinite. After being transformed by the impedance inversion network 27, the impedance at point G is in a grounded state. The adaptive input power distributor 1 inputs more power to the input terminal of the carrier power amplifier 23 through the first phase compensation network 21 and the first input matching network 22. The balun transformer unit 31 transforms the load impedance of the secondary coil LS1 to Z L ’, and makes Z L ’ = 2R opt to the impedance Z C ’ of the primary coil LP1. After the impedance Z C ’ is phase-shifted by the second phase compensation network 24, the load impedance Z Carrier seen by the carrier power amplifier 23 = 2R opt . The load impedance is doubled, improving the efficiency. In the high-power operating mode, the carrier power amplifier 23 and the peak power amplifier 26 operate simultaneously. The carrier power amplifier 23 enters the saturation state. The adaptive input power distributor 1 allocates more power to the peak power amplifier 26, increasing the gain of the peak power amplifier 26 path. The load impedance seen by the peak power amplifier 26 gradually decreases from infinity to R opt , and the load impedance seen by the carrier power amplifier 23 gradually decreases from infinity to R opt . The output powers of the carrier power amplifier 23 and the peak power amplifier 26 also gradually reach the maximum value, and the effective combination of the two paths of power is achieved through the balun transformer unit 31 of the voltage synthesis type power combining network 3.

[0143] Please refer to Figure 4 as shown in Figure 4 , which is the schematic diagram of the adaptive input power distributor 1 of the voltage synthesis type Doherty power amplifier 100 provided by the embodiment of the present invention. The adaptive input power distributor 1 is composed of a PI-type C-L-C. G1 and G2 are respectively the input admittances of the carrier power amplifier 23 at Port1 and the peak power amplifier 26 at Port2 of the peak power amplifier. The reactance of the series-connected first inductor L1 is jX1, and the reactances of the parallel-connected first capacitor C1 and second capacitor C2 are jB0. The reactance value jX1 of the first inductor L1 is selected (X1 = 2B0 / (B0 2 + G2 2 )) to transform the admittance Y 2B = G2 + jB0 at the Port2 port to its conjugate value Y * 2B = G2 - jB0. Y * 2B and the admittance Y 1B= G1 + jB0. The admittance Y0 after parallel connection is Y0 = G1 + G2 = 0.02 S, which is matched with the signal source impedance Z G (Z G = 1 / (G1 + G2) = 50 Ω) to achieve maximum power transfer of the signal. The amplitudes of the voltages V1 at Port1 and V2 at Port2 are equal, and the phase difference φ0 = -2 arctan(B0 / G1). The susceptance B0 of the two ports can be selected as needed to control the power distribution ratio between the two ports when the voltage - synthesized Doherty power amplifier 100 operates at the back - off output power. According to the characteristics of the power transistors, the values of G1, G2, and B0 are optimized so that when the voltage - synthesized Doherty power amplifier 100 operates in the low - power mode, more power is input to the carrier power amplifier 23, and when in the high - power mode, more power is input to the peak power amplifier 26.

[0144] It should be noted that the relevant circuits, resistors, capacitors, inductors, reactance components, transformers, and power amplifiers used in the present invention are all common circuits and components in the art. The corresponding specific indicators and parameters are adjusted according to actual applications and will not be elaborated in detail here.

[0145] Compared with the related technology, the voltage - synthesized Doherty power amplifier of the present invention is provided with an adaptive input power distributor, a power amplifier network, and a voltage - synthesized power combining network. Among them, the adaptive input power distributor includes a first capacitor, a second capacitor, and a first inductor; the power amplifier network includes a first phase compensation network, a first input matching network, a carrier power amplifier, a second phase compensation network, a second input matching network, a peak power amplifier, and an impedance inversion network; when the voltage - synthesized Doherty power amplifier operates in the low - power mode, the input power is in the low - input - power range, the peak power amplifier is turned off, and most of the input power is input to the carrier power amplifier; when the voltage - synthesized Doherty power amplifier operates in the high - power mode, the input power is in the high - input - power range, the carrier power amplifier enters the saturation amplification state, and most of the input power is input to the peak power amplifier, improving the gain of the peak power amplifier. This circuit enables the voltage - synthesized Doherty power amplifier of the present invention to dynamically control the power input to the carrier power amplifier and the peak power amplifier in the power amplifier network, and control the power flowing into the carrier power amplifier and the peak power amplifier according to the magnitude of the input power, so that the power amplification efficiency of the voltage - synthesized Doherty power amplifier of the present invention is high. In addition, through the adaptive input power distributor with variable power distribution ratio, the functions of self - distribution of input power and pre - distortion are realized, linearizing the output power of the voltage - synthesized Doherty power amplifier.

[0146] It should be noted that the various embodiments described above with reference to the accompanying drawings are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Those skilled in the art should understand that any modifications or equivalent substitutions to the present invention that do not depart from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include the plural form, and vice versa. Furthermore, unless otherwise specified, all or part of any embodiment may be used in combination with all or part of any other embodiment.

Claims

1. A voltage synthesis type Doherty power amplifier, characterized in that, The voltage synthesis Doherty power amplifier includes an adaptive input power divider, a power amplifier network, and a voltage synthesis power combining network; The adaptive input power divider includes a first capacitor, a second capacitor, and a first inductor; The power amplifier network includes a first phase compensation network, a first input matching network, a carrier power amplifier, a second phase compensation network, a second input matching network, a peak power amplifier, and an impedance inversion network; the first phase compensation network is used to connect an input signal and phase-shift the input signal, the first input matching network is used to achieve input impedance matching, the carrier power amplifier is used to amplify the power of the signal, the second phase compensation network is used to phase-shift the input signal, the second input matching network is used to achieve input impedance matching, the peak power amplifier is used to amplify the power of the signal, and the impedance inversion network is used to invert the input impedance; The voltage synthesis power combining network includes a balun transformer unit and a port impedance transformation network, and the port impedance transformation network is used to achieve output impedance matching; The first end of the first capacitor serves as the input end of the voltage synthesis Doherty power amplifier, and the first end of the first capacitor is respectively connected to the first end of the first inductor and the input end of the first phase compensation network; the second end of the first capacitor is grounded; The output end of the first phase compensation network is connected to the input end of the first input matching network, the output end of the first input matching network is connected to the input end of the carrier power amplifier, the output end of the carrier power amplifier is connected to the input end of the second phase compensation network, and the output end of the second phase compensation network is connected to the first end of the primary coil of the balun transformer unit; The second end of the first inductor is respectively connected to the first end of the second capacitor and the input end of the second input matching network; the second end of the second capacitor is grounded; The output end of the second input matching network is connected to the input end of the peak power amplifier, the output end of the peak power amplifier is connected to the input end of the impedance inversion network, and the output end of the impedance inversion network is connected to the second end of the primary coil of the balun transformer unit; The first end of the secondary coil of the balun transformer unit is connected to the input end of the port impedance transformation network, and the second end of the secondary coil of the balun transformer unit is grounded; The output end of the port impedance transformation network serves as the output end of the voltage synthesis Doherty power amplifier.

2. The voltage synthesis type Doherty power amplifier according to claim 1, wherein The carrier power amplifier includes a first transformer, a third capacitor, a fourth capacitor, a first power amplifier, a third power amplifier, and a fourth power amplifier; The output end of the carrier power amplifier has two, namely the first output end of the carrier power amplifier and the second output end of the carrier power amplifier respectively; The input end of the first power amplifier serves as the input end of the carrier power amplifier, and the output end of the first power amplifier is connected to the first end of the primary coil of the first transformer; The second end of the primary coil of the first transformer is grounded, and the center-tapped end of the primary coil of the first transformer is connected to the power supply voltage; The first end of the secondary coil of the first transformer is respectively connected to the input end of the third power amplifier and the first end of the fourth capacitor; The second end of the secondary coil of the first transformer is respectively connected to the input end of the fourth power amplifier and the second end of the fourth capacitor; The center-tapped end of the secondary coil of the first transformer is connected to the first end of the third capacitor; the second end of the third capacitor is grounded; The output end of the third power amplifier serves as the first output end of the carrier power amplifier; The output end of the fourth power amplifier serves as the second output end of the carrier power amplifier.

3. The voltage synthesis type Doherty power amplifier according to claim 2, wherein The second phase compensation network includes a seventh capacitor, an eighth capacitor, a first reactance element and a second reactance element, and both the first reactance element and the second reactance element are used to adjust the circuit passband; The input end of the second phase compensation network includes two, namely the first input end of the second phase compensation network and the second input end of the second phase compensation network; the output end of the second phase compensation network includes two, namely the first output end of the second phase compensation network and the second output end of the second phase compensation network; The first end of the seventh capacitor serves as the first input end of the second phase compensation network, and the first end of the seventh capacitor is connected to the first end of the first reactance element; The second end of the first reactance element serves as the first output end of the second phase compensation network, and the second end of the first reactance element is connected to the first end of the eighth capacitor; The second end of the seventh capacitor serves as the second input end of the second phase compensation network, and the second end of the seventh capacitor is connected to the first end of the second reactance element; The second end of the second reactance element serves as the second output end of the second phase compensation network, and the second end of the second reactance element is connected to the second end of the eighth capacitor.

4. The voltage synthesis type Doherty power amplifier according to claim 3, wherein The peak power amplifier includes a second transformer, a fifth capacitor, a sixth capacitor, a second power amplifier, a fifth power amplifier and a sixth power amplifier; The output end of the peak power amplifier includes two, namely the first output end of the peak power amplifier and the second output end of the peak power amplifier; The input end of the second power amplifier serves as the input end of the peak power amplifier, and the output end of the second power amplifier is connected to the first end of the primary coil of the second transformer; The second end of the primary coil of the second transformer is grounded, and the center-tapped end of the primary coil of the second transformer is connected to the power supply voltage; The first end of the secondary coil of the second transformer is respectively connected to the input end of the fifth power amplifier and the first end of the sixth capacitor; The second end of the secondary coil of the second transformer is respectively connected to the input end of the sixth power amplifier and the second end of the sixth capacitor; The center-tapped end of the secondary coil of the second transformer is connected to the first end of the fifth capacitor; the second end of the third capacitor is grounded; The output terminal of the fifth power amplifier serves as the first output terminal of the peak power amplifier; The output terminal of the sixth power amplifier serves as the second output terminal of the peak power amplifier.

5. The voltage synthesis type Doherty power amplifier according to claim 4, wherein The impedance inversion network includes a ninth capacitor, a tenth capacitor, a second inductor, a third inductor, a third reactance element, and a fourth reactance element, and both the third reactance element and the fourth reactance element are used to adjust the circuit passband; The input terminal of the impedance inversion network includes two, namely the first input terminal of the impedance inversion network and the second input terminal of the impedance inversion network; the output terminal of the impedance inversion network includes two, namely the first output terminal of the impedance inversion network and the second output terminal of the impedance inversion network; The first end of the ninth capacitor serves as the first input terminal of the impedance inversion network, and the first end of the ninth capacitor is connected to the first end of the third reactance element; The second end of the third reactance element is connected to the first end of the second inductor; The second end of the second inductor serves as the first output terminal of the impedance inversion network, and the second end of the second inductor is connected to the first end of the tenth capacitor; The second end of the ninth capacitor serves as the second input terminal of the impedance inversion network, and the second end of the ninth capacitor is connected to the first end of the fourth reactance element; The second end of the fourth reactance element is connected to the first end of the third inductor; The second end of the third inductor serves as the second output terminal of the impedance inversion network, and the second end of the third inductor is connected to the second end of the tenth capacitor.

6. The voltage synthesis type Doherty power amplifier according to claim 5, characterized in that, The balun transformer unit includes a third transformer and a fourth transformer; The first end of the primary coil of the balun transformer unit includes two, namely the first end of the primary coil of the third transformer and the second end of the primary coil of the third transformer; The center-tapped terminal of the primary coil of the third transformer is connected to the power supply voltage; The first end of the secondary coil of the third transformer serves as the first end of the secondary coil of the balun transformer unit; The second end of the secondary coil of the third transformer is connected to the first end of the secondary coil of the fourth transformer; The second end of the primary coil of the balun transformer unit includes two, namely the first end of the primary coil of the fourth transformer and the second end of the primary coil of the fourth transformer; The center-tapped terminal of the primary coil of the fourth transformer is connected to the power supply voltage; The second end of the secondary coil of the fourth transformer serves as the second end of the secondary coil of the balun transformer unit, and the second end of the secondary coil of the fourth transformer is grounded.

7. The voltage synthesis type Doherty power amplifier according to claim 1, characterized in that The port impedance transformation network is an eleventh capacitor, and the first end of the eleventh capacitor serves as the input terminal of the port impedance transformation network; the first end of the eleventh capacitor is grounded.

8. The voltage synthesis type Doherty power amplifier according to claim 4, wherein The circuit structures of the carrier power amplifier and the peak power amplifier are the same, and each component included in the carrier power amplifier corresponds one-to-one to each component included in the peak power amplifier, and the component performance and dimensions are the same.

9. The voltage synthesis type Doherty power amplifier according to claim 8, wherein, The optimal impedance of the carrier power amplifier and the optimal impedance of the peak power amplifier are both R opt ; When the voltage synthesis type Doherty power amplifier works in the low power operation mode, the load impedance of the secondary coil of the balun transformer unit is Z L ’, and it satisfies: Z L ’ = 2R opt , the load impedance of the carrier power amplifier is Z Carrier , and it satisfies: Z Carrier = 2R opt ; When the voltage synthesis type Doherty power amplifier operates in the high power operation mode, the load impedance of the peak power amplifier is Z peaking , and it satisfies: Z peaking =R opt .

10. The voltage synthesis type Doherty power amplifier according to claim 4, wherein The first power amplifier, the second power amplifier, the third power amplifier, the fourth power amplifier, the fifth power amplifier, and the sixth power amplifier are all implemented using transistors.

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