WO2023087627A1 - Broadband doherty power amplifier - Google Patents

Abstract

The present invention provides a broadband Doherty power amplifier, comprising a driving amplifier, a power divider, a first input matching network, a carrier power amplifier, a second input matching network, a peak power amplifier, and a power synthesis and phase shift network. The first input matching network is used for realizing -90-degree phase shift and impedance matching of a received signal; the second input matching network is used for realizing 0-degree phase shift and impedance matching of the received signal; the power synthesis and phase shift network is used for synthesizing the power of two paths of output signals and then outputting, after 90-degree phase shift and impedance matching are realized, the signals to an external system load; the power synthesis and phase shift network comprises a Balun impedance transformer, a first matching capacitor, a second matching capacitor, a third matching capacitor, a fourth matching capacitor, a fifth matching capacitor, a fourteenth inductor, and a fifteenth inductor. The broadband Doherty power amplifier of the present invention is wide in working frequency band, small in layout area, high in power additional efficiency, and high in linearity of output power.

Description

A Broadband Doherty Power Amplifier technical field

The invention relates to the field of circuit technology, in particular to a wideband Doherty power amplifier.

Background technique

In order to make full use of spectrum resources and increase the data transmission rate in modern wireless communication systems, the peak-to-average ratio (PAPR) signal format is adopted for modulation signals. High peak-to-average ratio signals impose strict requirements on the linearity of RF power amplifiers. In order to ensure the undistorted transmission of the signal, the wireless communication system requires the RF power amplifier to work in a power back-off state far away from the power compression point, so as to ensure the linear amplification of the RF signal. However, RF power amplifiers are often designed for a fixed power supply voltage, the load impedance is optimized at the maximum output power, and the efficiency is very low when the power is backed off. In order to improve the efficiency of RF power amplifiers during power back-off, the Doherty structure is a common method for designing RF power amplifiers.

A Doherty power amplifier in the related art generally includes a driver amplifier, a first input matching network, a carrier power amplifier, a second input matching network, a peak power amplifier, a first output matching network and a second output matching network. Please refer to FIG. 1, which is a schematic diagram of the circuit structure of a Doherty power amplifier in the related art, wherein, after the input signal is amplified by the drive amplifier, the input power splitter connected to the output of the drive amplifier divides the input power into two, Input to the input terminal of the carrier amplifier and the input terminal of the peak amplifier through the first input matching network and the second input matching network respectively. The output end of the carrier amplifier is output to the second output matching network through the first output matching network, wherein the first output matching network is generally a quarter-wavelength transmission line, and the output end of the peak amplifier is directly connected to the second output matching network. Two output matching networks connect the output loads. The working principle of the Doherty power amplifier in the related art is: the carrier amplifier is biased at Class AB or Class B, and the peak amplifier is biased at Class C. In the low output power state, the peak amplifier is off, and the load impedance of the carrier amplifier is 2Ropt. In the state of high output power, the peak amplifier is turned on, the load impedance of the carrier amplifier changes from 2Ropt to Ropt with the increase of input power, and the load impedance of the peak amplifier also gradually decreases from infinite value to Ropt with the increase of input power. Amplifiers complete power combining at output point A. Due to this change in load modulation, the Doherty PA exhibits higher efficiency during power back-off.

However, for the Doherty power amplifier of the related art, for the monolithic microwave integrated circuit, the size of the power divider and the quarter-wavelength transmission line of the traditional Doherty power amplifier are too large to be realized on the chip. At the same time, the bandwidth of the quarter-wavelength transmission line is limited, which is very unfavorable for the design of broadband amplifiers.

Therefore, it is necessary to provide a new broadband Doherty power amplifier to solve the above problems.

Contents of the invention

Aiming at the above deficiencies in the prior art, the present invention proposes a broadband Doherty power amplifier with wide operating frequency, small layout area, high power added efficiency and high linearity of output power.

In order to solve the above technical problems, an embodiment of the present invention provides a wideband Doherty power amplifier, which includes a driver amplifier, a power divider, a first input matching network, a carrier power amplifier, a second input matching network, Peaking power amplifiers and power combining and phase shifting networks;

The input end of the drive amplifier is used as the input end of the broadband Doherty power amplifier, the output end of the drive amplifier is connected to the input end of the power divider, and the drive amplifier is used to amplify the signal input from the outside;

The first output end of the power splitter is connected to the input end of the first input matching network, the second output end of the power splitter is connected to the input end of the second input matching network, and the power splitting The device is used to divide the amplified signal of the drive amplifier into two outputs and realize non-uniform distribution of power;

The output terminal of the first input matching network is connected to the input terminal of the carrier power amplifier, and the first input matching network is used to realize -90 degree phase shift and impedance matching of the received signal;

The output end of the carrier power amplifier is connected to the first input end of the power combining and phase shifting network, and the carrier power amplifier is used to amplify the received signal;

The output terminal of the second input matching network is connected to the input terminal of the peak power amplifier, and the second input matching network is used to realize 0 degree phase shift and impedance matching of the received signal;

The output terminal of the peak power amplifier is connected to the second input terminal of the power combining and phase shifting network, and the peak power amplifier is used to amplify the received signal;

The output end of described power synthesis and phase shifting network is used as the output end of described broadband Doherty power amplifier; Described power synthesis and phase shifting network are used for the output signal of described carrier power amplifier and the output signal of described peak power amplifier Power synthesis, and output to the external system load after realizing 90-degree phase shift and impedance matching;

Wherein, the power combining and phase-shifting network includes a balun impedance transformer, a first matching capacitor, a second matching capacitor, a third matching capacitor, a fourth matching capacitor, a fifth matching capacitor, a fourteenth inductance and a fifteenth inductance ;

The first end of the primary coil of the balun impedance transformer is used as the first input end of the power combining and phase shifting network, and the first ends of the primary coil of the balun impedance transformer are respectively connected to the first matching The first end of the capacitor and the first end of the fourth matching capacitor; the second end of the fourth matching capacitor is connected to ground after being connected in series with the fourteenth inductance;

The second end of the primary coil of the balun impedance transformer is respectively connected to the first end of the second matching capacitor and the first end of the third matching capacitor; the second end of the third matching capacitor is connected to grounding;

The first end of the secondary coil of the balun impedance transformer is used as the output end of the power combining and phase shifting network, and the first end of the secondary coil of the balun impedance transformer is connected to the fourth matching capacitor the second end of

The second end of the secondary coil of the balun impedance transformer is used as the second input end of the power combining and phase shifting network, and the second ends of the secondary coil of the balun impedance transformer are respectively connected to the first The second end of the second matching capacitor and the first end of the fifth matching capacitor; the second end of the fifth matching capacitor is connected to ground after being connected in series with the fifteenth inductor.

Preferably, the balun impedance transformer is a semi-lumped transformer with a 90-degree phase shift.

Preferably, the capacitance value of the first matching capacitor and the capacitance value of the second matching capacitor are both 1/(2πfZ _L ), and the capacitance value of the third matching capacitor is 1/(πfZ _L ); wherein, f is the operating frequency of the broadband Doherty power amplifier, and Z _L is the characteristic impedance of the system load.

Preferably, the first input matching network includes a fifth inductor, a seventh capacitor, and an eighth capacitor; the first end of the seventh capacitor serves as the input end of the first input matching network; the seventh capacitor The second end is respectively connected to the first end of the eighth capacitor and the first end of the third inductance; the second end of the third inductance is connected to ground; the second end of the eighth capacitor serves as the The output terminal of the first input matching network.

Preferably, the first input matching network further includes a first phase-modulating inductor; the first terminal of the first phase-modulating inductor is connected to the first terminal of the seventh capacitor, and the first terminal of the first phase-modulating inductor The two terminals are connected to the ground; the first phase-modulating inductance is a parameter-adjustable inductance.

Preferably, the second input matching network includes a sixth inductor, a seventh inductor, a ninth capacitor, and a tenth capacitor; the first end of the sixth inductor is used as the input end of the second input matching network, and the The first end of the sixth inductance is connected to the first end of the ninth capacitor, and the second end of the ninth capacitor is connected to ground; the second end of the sixth inductance is respectively connected to the tenth capacitor The first terminal of the first capacitor and the first terminal of the seventh inductor, the second terminal of the seventh inductor is connected to ground; the second terminal of the tenth capacitor is used as the output terminal of the second input matching network.

Preferably, the power divider is a Wilkinson power divider with lumped parameters, and the power divider includes a third inductor, a fourth inductor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor and a resistor;

The first terminal of the third capacitor is used as the input terminal of the power divider, and the first terminals of the third capacitor are respectively connected to the first terminals of the fifth capacitor;

The second end of the third capacitor is respectively connected to the first end of the third inductor and the first end of the fourth capacitor, and the second end of the third inductor is connected to ground;

The second end of the fourth capacitor is used as the first output end of the power divider, and the second end of the fourth capacitor is connected to the first end of the resistor;

The second end of the fifth capacitor is respectively connected to the first end of the fourth inductor and the first end of the sixth capacitor, and the second end of the fourth inductor is connected to ground;

The second end of the sixth capacitor serves as the second output end of the power divider, and the second end of the sixth capacitor is connected to the second end of the resistor.

Preferably, the drive amplifier, the carrier work and the peak power amplifier are all implemented by transistors, the carrier power amplifier includes a carrier resonance circuit for suppressing the second harmonic; the peak power amplifier includes a circuit for suppressing Carrier resonant circuit for the second harmonic.

Preferably, the carrier power amplifier includes an eighth inductor, a ninth inductor, a twelfth inductor, an eleventh capacitor, and a second transistor; the base of the second transistor is used as the input terminal of the carrier power amplifier, so The emitter of the second transistor is connected to ground, and the collector of the second transistor is respectively connected to the first terminal of the eleventh capacitor, the second terminal of the eighth inductor, and the first terminal of the ninth inductor. One end; the second end of the eleventh capacitor is connected to ground after being connected in series with the twelfth inductance; the first end of the eighth inductance is connected to the power supply voltage; the second end of the ninth inductance is used as The output terminal of the carrier power amplifier;

The peak power amplifier includes a tenth inductance, an eleventh inductance, a thirteenth inductance, a twelfth capacitor, and a third transistor; the base of the third transistor is used as an input terminal of the peak power amplifier, and the first The emitters of the three transistors are connected to ground, and the collectors of the third transistors are respectively connected to the first end of the twelfth capacitor, the second end of the tenth inductance, and the first end of the eleventh inductance. end; the second end of the sixth capacitor is connected to ground after being connected in series with the thirteenth inductance; the first end of the tenth inductance is connected to the power supply voltage; the second end of the eleventh inductance is used as the output of the peak power amplifier.

Preferably, the drive amplifier includes a first inductor, a second inductor, a first capacitor, a second capacitor, and a first transistor; the first end of the first capacitor serves as the input end of the drive amplifier, and the first The first end of a capacitor is connected to the ground after being connected in series with the first inductor; the second end of the first capacitor is connected to the base of the first transistor; the emitter of the first transistor is connected to the ground; The collector of the first transistor is respectively connected to the second end of the second inductor and the first end of the second capacitor; the first end of the second inductor is connected to a power supply voltage; the second capacitor The second end of the drive amplifier is used as the output end of the drive amplifier.

Compared with related technologies, the broadband Doherty power amplifier of the present invention divides the input signal into two paths through the power divider, and outputs them to the first input matching network and the second input matching network respectively, and one path of signal passes through the first input matching network and passes through the carrier The power amplifier amplifies the signal and outputs it to the power combining and phase shifting network, and the other signal is amplified by the second input matching network through the peak power amplifier and then output to the power combining and phase shifting network. The signals are combined and output. Among them, the second input matching network realizes 0 degree phase shift, the power combining and phase shifting network has 90 degree phase shifting, and the -90 degree phase shifting of the first input matching network can compensate the phase shift of +90 degree of power combining and phase shifting network degrees of phase difference, so as to realize the in-phase power combination of the two output signals of the carrier power amplifier and the peak power amplifier. The power combining and phase shifting network includes a balun impedance transformer, a first matching capacitor, a second matching capacitor, a third matching capacitor, a fourth matching capacitor, a fifth matching capacitor, a fourteenth inductor and a fifteenth inductor. The power combining and phase-shifting network of the circuit realizes the transformation of the load impedance, so that the quarter-wavelength transmission line of the related art is not needed, and the layout area of the circuit is greatly reduced. More preferably, the power combining and phase-shifting network adopts a circuit structure of a balun impedance transformer to ensure that the circuit works in a high-efficiency state, so that the power added efficiency of the broadband Doherty power amplifier of the present invention is high. The fourth matching capacitor and the fourteenth inductance resonate in series at the second harmonic frequency, and the fifth matching capacitor and the fifteenth inductance resonate in series at the second harmonic frequency, which deepens the depth of suppressing the second harmonic and improves the Linearity of output power.

Description of drawings

The present invention will be described in detail below in conjunction with the accompanying drawings. The content of the above or other aspects of the present invention will become clearer and easier to understand through the detailed description in conjunction with the following drawings. In the attached picture,

Fig. 1 is the application circuit structure schematic diagram of the broadband Doherty power amplifier of related art;

Fig. 2 is the application circuit structural representation of broadband Doherty power amplifier of the present invention;

Fig. 3 is the circuit diagram of the power combining and phase-shifting network of broadband Doherty power amplifier of the present invention;

4 is a schematic structural diagram of an application circuit of Embodiment 1 of a broadband Doherty power amplifier provided by an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of the application circuit of Embodiment 2 of the broadband Doherty power amplifier provided by the embodiment of the present invention.

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

The specific implementations/examples described here are specific specific implementations of the present invention, and are used to illustrate the concept of the present invention. limit. In addition to the embodiments described here, those skilled in the art can also adopt other obvious technical solutions based on the claims of the application and the contents disclosed in the description, and these technical solutions include adopting any obvious changes made to the embodiments described here. The replacement and modified technical solutions are all within the protection scope of the present invention.

(Embodiment 1)

An embodiment of the present invention provides a broadband Doherty power amplifier 100 .

The broadband Doherty power amplifier 100 includes a driver amplifier 1 , a power divider 2 , a first input matching network 3 , a carrier power amplifier 4 , a second input matching network 5 , a peak power amplifier 6 and a power combining and phase shifting network 7 .

specific:

The drive amplifier 1 is used to amplify the signal input from the outside.

The power splitter 2 is used for splitting the amplified signal of the drive amplifier 1 into two output paths and realizing non-uniform distribution of power.

The first input matching network 3 is used to realize -90 degree phase shift and impedance matching of the received signal.

The carrier power amplifier 4 is used to amplify the received signal.

The second input matching network 5 is used to achieve 0-degree phase shift and impedance matching for the received signal.

The peak power amplifier 6 is used to amplify the received signal.

The power combining and phase shifting network 7 is used. It is used to combine the output signal of the carrier power amplifier 4 and the output signal of the peak power amplifier 6 in power, realize 90-degree phase shift and impedance matching, and then output to an external system load.

Please refer to FIG. 2 , which is a schematic diagram of a circuit structure of a broadband Doherty power amplifier 100 according to the present invention. The circuit structure of the broadband Doherty power amplifier 100 is:

The input terminal of the driving amplifier 1 is used as the input terminal RFin of the broadband Doherty power amplifier 100 . The output terminal of the drive amplifier 1 is connected to the input terminal of the power divider 2 .

The first output terminal of the power divider 2 is connected to the input terminal of the first input matching network 3 , and the second output terminal of the power divider 2 is connected to the input terminal of the second input matching network 5 .

The output terminal of the first input matching network 3 is connected to the input terminal of the carrier power amplifier 4 .

The output terminal of the carrier power amplifier 4 is connected to the first input terminal OPY1 of the power combining and phase shifting network 7 .

The output end of the second input matching network 5 is connected to the input end of the peak power amplifier 6 .

The output terminal of the peaking power amplifier 6 is connected to the second input terminal OPY2 of the power combining and phase shifting network 7 .

The output terminal of the power combining and phase shifting network 7 is used as the output terminal RFout of the broadband Doherty power amplifier 100 .

Wherein, please refer to FIG. 3 , which is a circuit diagram of the power combining and phase shifting network of the broadband Doherty power amplifier 100 of the present invention. Specifically, the power combining and phase shifting network 7 includes a balun impedance transformer, a first matching capacitor C _b1 , a second matching capacitor, a third matching capacitor, a fourth matching capacitor, a fifth matching capacitor, and a fourteenth inductance L14 and the fifteenth inductance L15.

Wherein, the balun impedance transformer is a semi-lumped transformer with a 90-degree phase shift. The power combining and phase-shifting network 7 adopts the balun impedance transformer structure with semi-lumped phase-shifting 90 degrees, on the one hand realizes the transformation of the load impedance, thus does not need the quarter-wavelength transmission line of the related art, and the circuit The layout area is greatly reduced; on the other hand, it ensures that the circuit works in a state of high efficiency, so that the power added efficiency of the broadband Doherty power amplifier 100 of the present invention is high.

Please refer to FIG. 4 , which is a schematic structural diagram of an application circuit of Embodiment 1 of the broadband Doherty power amplifier 100 provided by the embodiment of the present invention.

In the first embodiment, the driving amplifier 1, the carrier power and the peak power amplifier 6 are all implemented by transistors. The use of transistors can make the layout area of the circuit small and easy for circuit integration. Of course, it is not limited thereto, and it is also possible to use other amplifier circuits or components for implementation.

The specific circuit structure of the broadband Doherty power amplifier 100 is:

The driving amplifier 1 includes a first inductor L1, a second inductor L2, a first capacitor C1, a second capacitor C2 and a first transistor Q1. The first terminal of the first capacitor C1 is used as the input terminal of the driving amplifier 1 . And the first end of the first capacitor C1 is connected to the ground GND after being connected in series with the first inductor L1. The second end of the first capacitor C1 is connected to the base of the first transistor Q1. The emitter of the first transistor Q1 is connected to the ground GND. The collector of the first transistor Q1 is respectively connected to the second terminal of the second inductor L2 and the first terminal of the second capacitor C2. The first terminal of the second inductor L2 is connected to the power supply voltage Vcc. The second terminal of the second capacitor C2 is used as the output terminal of the driving amplifier 1 .

The power splitter 2 includes a third inductor L3, a fourth inductor L4, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6 and a resistor R.

The first end of the third capacitor C3 is used as the input end of the power divider 2, and the first end of the third capacitor C3 is respectively connected to the first end of the fifth capacitor C5;

The second terminal of the third capacitor C3 is respectively connected to the first terminal of the third inductor L3 and the first terminal of the fourth capacitor C4. The second end of the third inductor L3 is connected to the ground GND.

The second end of the fourth capacitor C4 is used as the first output end of the power divider, and the second end of the fourth capacitor C4 is connected to the first end of the resistor R.

The second terminal of the fifth capacitor C5 is respectively connected to the first terminal of the fourth inductor L4 and the first terminal of the sixth capacitor C6. The second end of the fourth inductor L4 is connected to the ground GND.

The second end of the sixth capacitor C6 is used as the second output end of the power divider 2, and the second end of the sixth capacitor C6 is connected to the second end of the resistor R.

The power divider 2 is a Wilkinson power divider with lumped parameters. The carrier power amplifier 4 of the broadband Doherty power amplifier 100 is biased in class AB, and the peak power amplifier 6 is biased in class C, but the gain and input capacitance of the amplifier biased in class C increase with the increase of input power Increase, the input impedance changes with the input power, which directly affects the power distribution of the carrier power amplifier 4 and the peak power amplifier 6, and the discontinuous input impedance reduces the operating bandwidth of the broadband Doherty power amplifier 100. On the other hand, due to the difference in gain, when the broadband Doherty power amplifier 100 is at the maximum output power, the current and voltage of the peak power amplifier 6 are lower than the carrier power amplifier 4, causing the carrier power amplifier 4 to see a high load value, the peak power amplifier 6 sees a low load value, which reduces the combined output power, efficiency and linearity of the wideband Doherty power amplifier 100. In order to achieve desired broadband Doherty power amplifier 100 operating conditions and load modulation, when in low power mode, allocate more power to the carrier power amplifier 4, to improve the gain and efficiency of the carrier power amplifier 4, to prevent peak power Amplifier 6 switches on prematurely. In the high power mode, more power is allocated to the peak power amplifier 6, the gain of the peak power amplifier 6 is increased, the effective synthesis of two-way power is realized, and the linearity of the output power is improved at the same time. By selecting appropriate parameters, the Wilkinson power divider adopted by the power divider 2 can realize non-uniform distribution of power: at the time of maximum output power, the input impedance of the carrier power amplifier 4 is mismatched, and the peak power amplifier 6 The input impedance matches well with the output port of the Wilkinson power divider, and more power is input into the peak power amplifier 6; when the input power is reduced and enters the low power operation mode, the change of the input impedance of the peak power amplifier 6 causes it to be different from the Wilkinson power amplifier. The degree of impedance mismatch at the output port of the divider deepens, and more power is input into the carrier power amplifier 4, which improves the output gain and efficiency of the carrier power amplifier 4 at low input power. In general, the non-uniform power distribution ratio of the Wilkinson power divider adopted by the power divider 2 in the wideband Doherty power amplifier 100 needs to be compromised among bandwidth, size, gain and efficiency. The non-uniform power distribution network absorbs the input impedance variation of the peaking power amplifier 6 and increases the operating bandwidth of the wideband Doherty power amplifier 100, although the introduction of the Wilkinson power divider sacrifices a little circuit gain and efficiency.

The first input matching network 3 includes a fifth inductor L5, a seventh capacitor C7 and an eighth capacitor C8. The first terminal of the seventh capacitor C7 is used as the input terminal of the first input matching network 3 . The second terminal of the seventh capacitor C7 is respectively connected to the first terminal of the eighth capacitor C8 and the first terminal of the third inductor L3. The second end of the third inductor L3 is connected to the ground GND. The second terminal of the eighth capacitor C8 is used as the output terminal of the first input matching network 3 .

Wherein, the fifth inductor L5, the seventh capacitor C7 and the eighth capacitor C8 form a high-pass filter matching network. The high-pass filter matching network formed by the fifth inductor L5, the seventh capacitor C7, and the eighth capacitor C8 not only realizes impedance matching, but also plays a role of phase shifting -90 degrees to compensate the power combining and phase shifting network 7 The phase shift of the +90 degree phase difference realizes the in-phase power combination of the two output signals of the carrier power amplifier 4 and the peak power amplifier 6.

The carrier power amplifier 4 includes a carrier resonance circuit for suppressing the second harmonic. The carrier power amplifier 4 includes an eighth inductor L8, a ninth inductor L9, a twelfth inductor L12, an eleventh capacitor C11 and a second transistor Q2. The base of the second transistor Q2 serves as the input terminal of the carrier power amplifier 4 . The emitter of the second transistor Q2 is connected to the ground GND. The collector of the second transistor Q2 is respectively connected to the first terminal of the eleventh capacitor C11 , the second terminal of the eighth inductor L8 and the first terminal of the ninth inductor L9 . The second end of the eleventh capacitor C11 is connected to the ground GND after being connected in series with the twelfth inductor L12. A first end of the eighth inductor L8 is connected to a power supply voltage Vcc. The second terminal of the ninth inductor L9 is used as the output terminal of the carrier power amplifier 4 .

Among them, in order to suppress the second harmonic, the collector of the second transistor Q2 is connected in parallel with the eleventh capacitor C11, and the twelfth inductor L12 is used as a bonding inductor, and the eleventh capacitor C11 and the twelfth inductor L12 resonate in series in the second Harmonic frequency, forming an approximate short circuit to ground.

The second input matching network 5 includes a sixth inductor L6, a seventh inductor L7, a ninth capacitor C9 and a tenth capacitor C10. The first terminal of the sixth inductor L6 serves as the input terminal of the second input matching network 5 . And the first end of the sixth inductor L6 is connected to the first end of the ninth capacitor C9. The second end of the ninth capacitor C9 is connected to the ground GND. The second terminal of the sixth inductor L6 is respectively connected to the first terminal of the tenth capacitor C10 and the first terminal of the seventh inductor L7. The second end of the seventh inductor L7 is connected to the ground GND. The second terminal of the tenth capacitor C10 is used as the output terminal of the second input matching network 5 .

Wherein, the phase shifts of the signals output by the power divider 2 cancel each other through the matching network formed by the sixth inductor L6, the seventh inductor L7, the ninth capacitor C9 and the tenth capacitor C10, and no phase shift occurs.

The peak power amplifier 6 includes a carrier resonance circuit for suppressing the second harmonic. The peak power amplifier 6 includes a tenth inductor L10, an eleventh inductor L11, a thirteenth inductor 13, a twelfth capacitor C12 and a third transistor Q3. The base of the third transistor Q3 is used as the input terminal of the peak power amplifier 6 . The emitter of the third transistor Q3 is connected to the ground GND. The collector of the third transistor Q3 is respectively connected to the first end of the twelfth capacitor C12, the second end of the tenth inductor L10, and the first end of the eleventh inductor L11. The second end of the sixth capacitor C6 is connected to the ground GND after being connected in series with the thirteenth inductor 13 . A first end of the tenth inductor L10 is connected to a power supply voltage Vcc. The second terminal of the eleventh inductor L11 is used as the output terminal of the peak power amplifier 6 .

Among them, in order to suppress the second harmonic, the collector of the third transistor Q3 is connected in parallel with the twelfth capacitor C12, the thirteenth inductor 13 is used as a bonding inductor, and the twelfth capacitor C12 and the thirteenth inductor 13 resonate in series The second harmonic frequency forms an approximate short circuit to ground.

The circuit structure of described power combining and phase-shifting network 7 is:

The first end of the primary coil Lp of the balun impedance transformer serves as the first input end of the power combining and phase shifting network 7 . And the first end of the primary coil Lp of the balun impedance transformer is respectively connected to the first end of the first matching capacitor C _b1 and the first end of the fourth matching capacitor C _b4 . The second end of the fourth matching capacitor C _b4 is connected to the ground GND after being connected in series with the fourteenth inductor L14 .

The second end of the primary coil Lp of the balun impedance transformer is respectively connected to the first end of the second matching capacitor C _b2 and the first end of the third matching capacitor C _b3 . The second end of the third matching capacitor C _b3 is connected to the ground GND.

The first end of the secondary coil Ls of the balun impedance transformer serves as the output end of the power combining and phase shifting network 7 . And the first end of the secondary coil Ls of the balun impedance transformer is connected to the second end of the fourth matching capacitor C _b4 .

The second end of the secondary coil Ls of the balun impedance transformer serves as the second input end of the power combining and phase shifting network 7 . And the second end of the secondary coil Ls of the balun impedance transformer is respectively connected to the second end of the second matching capacitor C _b2 and the first end of the fifth matching capacitor C _b5 . The second end of the fifth matching capacitor C _b5 is connected to the ground GND after being connected in series with the fifteenth inductor L15 .

In the first embodiment, the capacitance value of the first matching capacitor C _b1 and the capacitance value of the second matching capacitor C _b2 are both 1/(2πfZ _L ), and the capacitance value of the third matching capacitor C _b3 is 1/(πfZ _L ). Wherein, f is the operating frequency of the broadband Doherty power amplifier 100, and Z _L is the characteristic impedance of the system load. When the broadband Doherty power amplifier 100 works in the low output power mode, the peak power amplifier is in the off state, and the output impedance is close to an open circuit state. After 90 degrees of phase shifting, the impedance presents a close to short circuit state, and the carrier power amplifier 4 works in a single-ended state. In the amplifier state, the impedance seen by the output terminal of the carrier power amplifier 4 is 2Z _L , and the higher load impedance ensures that the carrier power amplifier 4 works in a state of high efficiency. When the broadband Doherty power amplifier 100 works in the high output power mode, the impedance seen at the output end of the carrier amplifier changes from 2Z _L to Z _L as the output power increases, and at the same time the impedance at the output end of the peak power amplifier gradually changes from the low impedance region Change to Z _L . This structure makes the isolation port of the balun impedance transformer of the power combining and phase shifting network 7 provide special port conditions to obtain active modulation of the load impedance. The isolated ports are opposite ends of the primary coil L _p , namely the first end and the second end of the primary coil L _p . The output end of the carrier power amplifier 4 of the traditional broadband Doherty power amplifier 100 is connected to a quarter-wavelength transmission line for transformation of load impedance. This quarter-wavelength transmission line realizes impedance transformation by phase-shifting the impedance by 90 degrees. When designing the wideband Doherty power amplifier 100 for a monolithic microwave integrated circuit, the balun impedance with a semi-lumped phase shift of 90 degrees can be used. A transformer is used to replace the impedance transformation.

The power combining and phase-shifting network 7 is connected in parallel with the fourth matching capacitor C _b4 and the fifth matching capacitor C _b5 , the fourteenth inductance L14 and the fifteenth inductance L15 are used as bonding inductances, and the fourteenth inductance in the first embodiment Both the inductance values of L14 and the fifteenth inductor L15 are 2. The fourth matching capacitor C _b4 and the fourteenth inductance L14 resonate in series at the second harmonic frequency, and the fifth matching capacitor C _b5 and the fifteenth inductance L15 resonate in series at the second harmonic frequency, both of which deepen the suppression of the second harmonic frequency The depth of harmonics improves the linearity of output power.

(Example 2)

Embodiment 2 provides a broadband Doherty power amplifier 200 . Please refer to FIG. 5 , which is a schematic structural diagram of an application circuit of Embodiment 2 of the broadband Doherty power amplifier 200 provided by the embodiment of the present invention.

The circuit structure of the wideband Doherty power amplifier 200 is basically the same as that of the wideband Doherty power amplifier 100 . The difference between the circuit structure of the broadband Doherty power amplifier 200 and the broadband Doherty power amplifier 100 is:

The first input matching network 3 also includes a first phase-modulating inductor La. Specifically, the first phase-modulating inductor La is connected between the first end of the seventh capacitor C7 and the ground GND. That is, the circuit connection relationship is: the first end of the first phase-modulating inductor La is connected to the first end of the seventh capacitor C7, and the second end of the first phase-modulating inductor La is connected to the ground GND.

The first phase-modulating inductor La is used to adjust the phase shift of the first input matching network 3 . The first phase-modulating inductor La is an adjustable parameter inductor. In some cases, both the input capacitance generated by the parasitic input terminal of the second transistor Q2 of the power amplifier and the input capacitance generated by the input terminal parasitic of the third transistor Q3 have a certain influence, and it is necessary to adjust the seventh capacitor C7, The phase of the high-pass filter matching network composed of the fifth inductor L5 and the eighth capacitor C8 is used to offset the influence of the parasitic input capacitor on the phase, and ensure that the phase difference between the output signals of Q2 and Q3 is 90 degrees to compensate for the power combining and phase shifting network 7 The phase shift of 90 degrees of phase difference realizes the in-phase power combination of the two output signals of the carrier power amplifier 4 and the peak power amplifier 6, and the output power is the largest and the efficiency is the highest.

It should be pointed out that the relevant circuits, resistors, capacitors, inductors and power amplifiers used in this utility model are all commonly used circuits and components in the field, and the corresponding specific indicators and parameters are adjusted according to actual applications. Here, no detailed description will be given. repeat.

Compared with related technologies, the broadband Doherty power amplifier of the present invention divides the input signal into two paths through the power divider, and outputs them to the first input matching network and the second input matching network respectively, and one path of signal passes through the first input matching network and passes through the carrier The power amplifier amplifies the signal and outputs it to the power combining and phase shifting network, and the other signal is amplified by the second input matching network through the peak power amplifier and then output to the power combining and phase shifting network. The signals are combined and output. Among them, the second input matching network realizes 0 degree phase shift, the power combining and phase shifting network has 90 degree phase shifting, and the -90 degree phase shifting of the first input matching network can compensate the phase shift of +90 degree of power combining and phase shifting network degrees of phase difference, so as to realize the in-phase power combination of the two output signals of the carrier power amplifier and the peak power amplifier. The power combining and phase shifting network includes a balun impedance transformer, a first matching capacitor, a second matching capacitor, a third matching capacitor, a fourth matching capacitor, a fifth matching capacitor, a fourteenth inductor and a fifteenth inductor. The power combining and phase-shifting network of the circuit realizes the transformation of the load impedance, so that the quarter-wavelength transmission line of the related art is not needed, and the layout area of the circuit is greatly reduced. More preferably, the power combining and phase-shifting network adopts a circuit structure of a balun impedance transformer to ensure that the circuit works in a high-efficiency state, so that the power added efficiency of the broadband Doherty power amplifier of the present invention is high. The fourth matching capacitor and the fourteenth inductance resonate in series at the second harmonic frequency, and the fifth matching capacitor and the fifteenth inductance resonate in series at the second harmonic frequency, which deepens the depth of suppressing the second harmonic and improves the Linearity of output power.

It should be noted that the various embodiments described above with reference to the accompanying drawings are only used to illustrate the present invention rather than limit the scope of the present invention. Those of ordinary skill in the art should understand that without departing from the spirit and scope of the present invention Any modifications or equivalent replacements made to the present invention shall fall within the scope of the present invention. Further, words appearing in the singular include the plural and vice versa unless the context otherwise requires. Additionally, all or a portion of any embodiment may be utilized with all or a portion of any other embodiment, unless stated otherwise.

Claims (10)

1. A kind of broadband Doherty power amplifier, it is characterized in that, described broadband Doherty power amplifier comprises driver amplifier, power splitter, first input matching network, carrier power amplifier, second input matching network, peak power amplifier and power combining and phase shifting network;

   The input end of the drive amplifier is used as the input end of the broadband Doherty power amplifier, the output end of the drive amplifier is connected to the input end of the power divider, and the drive amplifier is used to amplify the signal input from the outside;

   The first output end of the power splitter is connected to the input end of the first input matching network, the second output end of the power splitter is connected to the input end of the second input matching network, and the power splitting The device is used to divide the amplified signal of the drive amplifier into two outputs and realize non-uniform distribution of power;

   The output terminal of the first input matching network is connected to the input terminal of the carrier power amplifier, and the first input matching network is used to realize -90 degree phase shift and impedance matching of the received signal;

   The output end of the carrier power amplifier is connected to the first input end of the power combining and phase shifting network, and the carrier power amplifier is used to amplify the received signal;

   The output terminal of the second input matching network is connected to the input terminal of the peak power amplifier, and the second input matching network is used to achieve 0-degree phase shift and impedance matching for the received signal;

   The output terminal of the peak power amplifier is connected to the second input terminal of the power combining and phase shifting network, and the peak power amplifier is used to amplify the received signal;

   The output end of described power synthesis and phase shifting network is used as the output end of described broadband Doherty power amplifier; Described power synthesis and phase shifting network are used for the output signal of described carrier power amplifier and the output signal of described peak power amplifier Power synthesis, and output to the external system load after realizing 90-degree phase shift and impedance matching;

   Wherein, the power combining and phase-shifting network includes a balun impedance transformer, a first matching capacitor, a second matching capacitor, a third matching capacitor, a fourth matching capacitor, a fifth matching capacitor, a fourteenth inductance and a fifteenth inductance ;

   The first end of the primary coil of the balun impedance transformer is used as the first input end of the power combining and phase shifting network, and the first ends of the primary coil of the balun impedance transformer are respectively connected to the first matching The first end of the capacitor and the first end of the fourth matching capacitor; the second end of the fourth matching capacitor is connected to ground after being connected in series with the fourteenth inductance;

   The second end of the primary coil of the balun impedance transformer is respectively connected to the first end of the second matching capacitor and the first end of the third matching capacitor; the second end of the third matching capacitor is connected to grounding;

   The first end of the secondary coil of the balun impedance transformer is used as the output end of the power combining and phase shifting network, and the first end of the secondary coil of the balun impedance transformer is connected to the fourth matching capacitor the second end of

   The second end of the secondary coil of the balun impedance transformer is used as the second input end of the power combining and phase shifting network, and the second ends of the secondary coil of the balun impedance transformer are respectively connected to the first The second end of the second matching capacitor and the first end of the fifth matching capacitor; the second end of the fifth matching capacitor is connected to ground after being connected in series with the fifteenth inductor.
2. The broadband Doherty power amplifier according to claim 1, wherein the balun impedance transformer is a semi-lumped transformer with a 90-degree phase shift.
3. The broadband Doherty power amplifier according to claim 1, wherein the capacitance value of the first matching capacitor and the capacitance value of the second matching capacitor are 1/(2πfZ _L ), and the third matching capacitor The capacitance value of is 1/(πfZ _L ); wherein, f is the operating frequency of the broadband Doherty power amplifier, and Z _L is the characteristic impedance of the system load.
4. The broadband Doherty power amplifier according to claim 1, wherein the first input matching network comprises a fifth inductor, a seventh capacitor and an eighth capacitor; the first end of the seventh capacitor serves as the first Input the input end of the matching network; the second end of the seventh capacitor is respectively connected to the first end of the eighth capacitor and the first end of the third inductor; the second end of the third inductor is connected to Grounded; the second end of the eighth capacitor serves as the output end of the first input matching network.
5. Broadband Doherty power amplifier according to claim 4, is characterized in that,

   The first input matching network also includes a first phase-modulating inductor; the first end of the first phase-modulating inductor is connected to the first end of the seventh capacitor, and the second end of the first phase-modulating inductor is connected to to ground; the first phase-modulating inductance is a parameter-adjustable inductance.
6. The broadband Doherty power amplifier according to claim 1, wherein the second input matching network comprises a sixth inductance, a seventh inductance, a ninth capacitor and a tenth capacitor; the first end of the sixth inductance serves as The input end of the second input matching network, and the first end of the sixth inductor is connected to the first end of the ninth capacitor, and the second end of the ninth capacitor is connected to ground; the sixth The second end of the inductance is respectively connected to the first end of the tenth capacitor and the first end of the seventh inductance, and the second end of the seventh inductance is connected to ground; the second end of the tenth capacitor As the output of the second input matching network.
7. The broadband Doherty power amplifier according to claim 1, wherein the power divider is a Wilkinson power divider of lumped parameters, and the power divider comprises a third inductance, a fourth inductance, a third capacitor, a first Four capacitors, fifth capacitors, sixth capacitors and resistors;

   The first terminal of the third capacitor is used as the input terminal of the power divider, and the first terminals of the third capacitor are respectively connected to the first terminals of the fifth capacitor;

   The second end of the third capacitor is respectively connected to the first end of the third inductor and the first end of the fourth capacitor, and the second end of the third inductor is connected to ground;

   The second end of the fourth capacitor is used as the first output end of the power divider, and the second end of the fourth capacitor is connected to the first end of the resistor;

   The second end of the fifth capacitor is respectively connected to the first end of the fourth inductor and the first end of the sixth capacitor, and the second end of the fourth inductor is connected to ground;

   The second end of the sixth capacitor serves as the second output end of the power divider, and the second end of the sixth capacitor is connected to the second end of the resistor.
8. According to the described wide band Doherty power amplifier of claim 1, it is characterized in that, described driving amplifier, described carrier work and described peak power amplifier all adopt transistor to realize, and described carrier power amplifier comprises the Carrier resonance circuit; the peak power amplifier includes a carrier resonance circuit for suppressing the second harmonic.
9. Broadband Doherty power amplifier according to claim 8, is characterized in that,

   The carrier power amplifier includes an eighth inductance, a ninth inductance, a twelfth inductance, an eleventh capacitor, and a second transistor; the base of the second transistor is used as an input terminal of the carrier power amplifier, and the second The emitter of the transistor is connected to ground, and the collector of the second transistor is respectively connected to the first end of the eleventh capacitor, the second end of the eighth inductor, and the first end of the ninth inductor; The second end of the eleventh capacitor is connected to ground after being connected in series with the twelfth inductance; the first end of the eighth inductance is connected to a power supply voltage; the second end of the ninth inductance is used as the carrier the output of the power amplifier;

   The peak power amplifier includes a tenth inductance, an eleventh inductance, a thirteenth inductance, a twelfth capacitor, and a third transistor; the base of the third transistor is used as an input terminal of the peak power amplifier, and the first The emitters of the three transistors are connected to ground, and the collectors of the third transistors are respectively connected to the first end of the twelfth capacitor, the second end of the tenth inductance, and the first end of the eleventh inductance. end; the second end of the sixth capacitor is connected to ground after being connected in series with the thirteenth inductance; the first end of the tenth inductance is connected to the power supply voltage; the second end of the eleventh inductance is used as the output of the peak power amplifier.
10. According to the described broadband Doherty power amplifier of claim 8, it is characterized in that, described driver amplifier comprises first inductance, second inductance, first electric capacity, second electric capacity and first transistor; The first end of described first electric capacity As the input end of the drive amplifier, and the first end of the first capacitor is connected to ground after being connected in series with the first inductor; the second end of the first capacitor is connected to the base of the first transistor The emitter of the first transistor is connected to ground; the collector of the first transistor is respectively connected to the second end of the second inductor and the first end of the second capacitor; The first end is connected to the power supply voltage; the second end of the second capacitor is used as the output end of the drive amplifier.

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