CN118157594A - Broadband doherty power amplifier - Google Patents
Broadband doherty power amplifier Download PDFInfo
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- CN118157594A CN118157594A CN202410177987.8A CN202410177987A CN118157594A CN 118157594 A CN118157594 A CN 118157594A CN 202410177987 A CN202410177987 A CN 202410177987A CN 118157594 A CN118157594 A CN 118157594A
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- 230000010363 phase shift Effects 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 16
- 230000009466 transformation Effects 0.000 description 9
- 238000004891 communication Methods 0.000 description 7
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- 238000006243 chemical reaction Methods 0.000 description 2
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- 238000011161 development Methods 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
- H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
- H03F1/0288—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers using a main and one or several auxiliary peaking amplifiers whereby the load is connected to the main amplifier using an impedance inverter, e.g. Doherty amplifiers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/42—Modifications of amplifiers to extend the bandwidth
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/56—Modifications of input or output impedances, not otherwise provided for
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
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Abstract
The invention provides a broadband doherty power amplifier, which comprises a main path power amplifier, an auxiliary path power amplifier, a quarter-wavelength transmission line, a transformer, an output matching network, an input matching network and a phase shift network, wherein the input matching network and the phase shift network receive input signals and generate a main path power amplifier signal and an auxiliary path power amplifier signal with 90 DEG phase difference; the output of the auxiliary path power amplifier is connected to a quarter wavelength transmission line, and the auxiliary path power amplifier signal is received by the auxiliary path power amplifier and connected to a first input of a transformer through the quarter wavelength transmission line; the main power amplifier receives the main power amplifier signal and outputs it to the second input of the transformer; the output of the transformer is connected to the input of an output matching network and the amplified signal is output through the output matching network.
Description
Technical Field
The present invention relates to radio frequency front end integrated circuit designs, and more particularly to a transformer-based broadband Doherty (Doherty) power amplifier.
Background
With the rapid development of wireless communication technology, modulation technologies such as Orthogonal Frequency Division Multiplexing (OFDM) and Quadrature Amplitude Modulation (QAM) are widely used in wireless communication systems to achieve higher spectrum availability and larger transmission data volume, but at the same time, the problem of peak-to-average power ratio (PAPR) is brought, so that a great challenge is brought to the design of a radio frequency power amplifier. A high PAPR means that the power amplifier needs to operate in a power back-off region, thereby causing deterioration in efficiency of a transmitting end.
The doherty power amplifier is one way to improve the back-off efficiency of the power amplifier, and fig. 1 is a block diagram showing a conventional doherty power amplifier. Referring to fig. 1, the doherty power amplifier includes two power amplifiers, i.e., a main power amplifier and an auxiliary power amplifier, typically the main power amplifier is biased in class AB and the auxiliary power amplifier is biased in class C, wherein a transmission line of the main power amplifier output is a quarter wavelength line with a characteristic impedance Ropt (Ropt is a best matching point impedance of the main power amplifier and the auxiliary power amplifier) for realizing impedance transformation, and an output matching network matches the impedance from 50 ohms to Ropt/2, and a phase transformer of an input terminal is used for compensating a phase difference of the main auxiliary circuit.
Disclosure of Invention
According to one aspect of the present invention, there is provided a wideband Doherty (Doherty) power amplifier comprising: a main and auxiliary power amplifier, a quarter wavelength transmission line, a transformer, an output matching network, an input matching network and a phase shift network, wherein the input matching network and the phase shift network receive an input signal and generate a main and auxiliary power amplifier signal having a 90 ° phase difference; the output of the auxiliary path power amplifier is connected to a quarter wavelength transmission line, and the auxiliary path power amplifier signal is received by the auxiliary path power amplifier and connected to a first input of a transformer through the quarter wavelength transmission line; the main power amplifier receives the main power amplifier signal and outputs it to the second input of the transformer; the output of the transformer is connected to the input of an output matching network and the amplified signal is output through the output matching network.
According to one aspect of the invention, a wideband Doherty (Doherty) power amplifier is provided, wherein the main path power amplifier is biased as a class AB power amplifier.
According to one aspect of the invention, a wideband Doherty (Doherty) power amplifier is provided, wherein the auxiliary path power amplifier is biased as a class C power amplifier.
According to one aspect of the present invention, there is provided a broadband Doherty (Doherty) power amplifier further comprising a main path impedance matching network connected between an output of the main path power amplifier and a second input of the transformer.
According to one aspect of the present invention, a broadband Doherty (Doherty) power amplifier is provided, wherein the main and auxiliary path power amplifiers are configured to have a best matching point impedance Ropt.
According to one aspect of the present invention, there is provided a broadband Doherty (Doherty) power amplifier, wherein a characteristic impedance of the quarter-wavelength transmission line is configured as a best matching point impedance Ropt.
According to one aspect of the present invention, there is provided a broadband Doherty (Doherty) power amplifier, wherein an input impedance of an output matching network is configured to be 2 times an optimal matching point impedance Ropt, and a main path and an auxiliary path achieve power combining and impedance modulation effects through the transformer.
According to one aspect of the present invention, a wideband Doherty (Doherty) power amplifier is provided, wherein the wideband Doherty power amplifier is configured as a power amplifier for an N77 or N79 frequency band.
According to one aspect of the present invention, a wideband Doherty (Doherty) power amplifier is provided, wherein the wideband Doherty power amplifier is implemented by one of HBT, CMOS, BJT, biCMOS, gaN processes.
According to one aspect of the present invention, there is provided a broadband Doherty (Doherty) power amplifier, wherein the main and auxiliary path power amplifiers are configured as power amplifiers of a source common gate structure.
Drawings
Fig. 1 is a block diagram showing a conventional doherty power amplifier;
Fig. 2 is a schematic diagram showing the low power region operating principle of the doherty power amplifier;
fig. 3 is a schematic diagram showing the principle of operation of the doherty power amplifier in the high power region;
fig. 4 is a schematic diagram showing an efficiency curve of a doherty power amplifier;
Fig. 5 is a schematic diagram illustrating a doherty power amplifier according to an embodiment of the invention;
Fig. 6 is a schematic diagram illustrating the low power region operating principle of a doherty power amplifier according to an embodiment of the invention;
Fig. 7 is a schematic diagram illustrating the high power region operating principle of a doherty power amplifier according to an embodiment of the invention; and
Fig. 8 is a schematic diagram illustrating a doherty power amplifier according to another embodiment of the invention.
Detailed Description
Before proceeding with the following detailed description, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms "coupled," "connected," and derivatives thereof, refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms "transmit," "receive," and "communicate," and derivatives thereof, encompass both direct and indirect communication. The terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation. The term "or" is inclusive, meaning and/or. The phrase "associated with … …" and its derivatives are intended to include, be included within, interconnect, contain, be included within, connect with, or be coupled with … …, be coupled with or be coupled with … …, be in communication with … …, mate, interleave, juxtapose, be proximate to, bind or bind with … …, have attributes, have relationships or be in relationship with … …, etc. The term "controller" refers to any device, system, or portion thereof that controls at least one operation. Such a controller may be implemented in hardware, or a combination of hardware and software and/or firmware. The functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. The phrase "at least one," when used with a list of items, means that different combinations of one or more of the listed items may be used, and that only one item in the list may be required. For example, "at least one of A, B, C" includes any one of the following combinations: A. b, C, A and B, A and C, B and C, A and B and C.
Definitions for other specific words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases.
In this patent document, the application combinations of circuit blocks and the division of sub-circuit blocks are for illustration only, and the application combinations of circuit blocks and the division of sub-circuit blocks may have different manners without departing from the scope of the disclosure.
Figures 1 through 8, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will appreciate that the principles of the present disclosure may be implemented in any suitably arranged system or device.
Fig. 2 is a schematic diagram showing the low power region operation principle of the doherty power amplifier.
The doherty power amplifier can operate in a low power region and a high power region, wherein the doherty power amplifier can be considered to operate in the low power region before the auxiliary circuit power amplifier is turned on.
Doherty power amplifier operating in low power region as shown in fig. 2, since the auxiliary path power amplifier is biased in class C, when the doherty power amplifier is configured to turn on the low power region, the signal is completely transmitted by the main path power amplifier, which has an output impedance of 2Ropt due to the quarter-wavelength line. Through the quarter wavelength line, its output impedance is Ropt/2, and since the auxiliary circuit power amplifier is not turned on at this time, the input impedance of the output matching network is Ropt/2.
Fig. 3 is a schematic diagram showing the principle of operation of the doherty power amplifier in the high power region.
When the doherty power amplifier is configured to turn on the high power region, the main and auxiliary power amplifiers are turned on simultaneously at this time, and the output impedances of the main and auxiliary power amplifiers are Ropt at this time in consideration of the effect of load pulling. Through the quarter wavelength line, the output impedance of the quarter wavelength line is Ropt, and thus, the input impedance of the output matching network is Ropt/2.
The conversion of the doherty power amplifier from the high-power saturation region to the low-power saturation region can realize 6dB rollback, and the low-power region only works as the main power amplifier, and meanwhile, the output impedance is higher than 2Ropt, so that the rollback efficiency can be improved.
Fig. 4 is a schematic diagram showing the efficiency curve of a doherty power amplifier.
Referring to fig. 4, the efficiency of the doherty power amplifier is improved with respect to the 6dB back-off point of the conventional class AB power amplifier (general class AB power amplifier).
However, with conventional doherty power amplifier arrangements, the introduction of quarter-wavelength lines in the main power amplifier path to achieve impedance transformation also introduces matching network bandwidth issues. As shown in fig. 2, in the low power region, the impedance transformation ratio of the quarter-wavelength line in the main power amplifier path is as high as 4 (from 2Ropt to Ropt/2), so that high back-off efficiency can be achieved only within a narrow bandwidth. Also in the doherty power amplifier arrangement shown in fig. 2 and 3, the output matching network needs to achieve an impedance conversion of the impedance from 50 ohms to Ropt/2, which also limits the operating bandwidth of the overall arrangement.
Aiming at the bandwidth problem of the traditional doherty power amplifier, the invention provides a novel doherty power amplifier based on a transformer, which is used for realizing the purpose of high rollback efficiency in a broadband.
Fig. 5 is a schematic diagram illustrating a doherty power amplifier according to an embodiment of the invention.
The doherty power amplifier according to an embodiment of the invention comprises a main path power amplifier and an auxiliary path power amplifier, a quarter-wavelength transmission line, a transformer, an output matching network, an input matching network and a phase shift network.
Referring to fig. 5, a signal is input from an input terminal and supplied to an input matching network and a phase shift network, two signals (a main power amplifier signal and an auxiliary power amplifier signal) having a phase difference of 90 ° are generated through the input matching network and the phase shift network, and are supplied to the main power amplifier and the auxiliary power amplifier, respectively, wherein an output of the auxiliary power amplifier is connected to a quarter-wavelength transmission line and is connected to a first input terminal of a transformer through the quarter-wavelength transmission line. The output of the main power amplifier is connected to a second input of the transformer. The output of the transformer is connected to the input of the output matching network and the amplified signal is output through the output matching network.
Compared with the traditional doherty power amplifier, the doherty power amplifier adjusts an output matching network to reduce the impedance transformation ratio of the output matching network, and not only introduces a transformer, but also places a quarter-wavelength transmission line in an auxiliary circuit.
Fig. 6 is a schematic diagram illustrating the low power region operation principle of the doherty power amplifier according to an embodiment of the present invention.
The doherty power amplifier according to an embodiment of the invention is shown in fig. 6, since the auxiliary path power amplifier is biased in class C, when the doherty power amplifier is configured to turn on the low power region, the signal is completely transmitted by the main path power amplifier, and the output impedance at the main path power amplifier is 2Ropt due to the quarter wavelength line and the transformer. And since the auxiliary power amplifier is configured to be not turned on, the output of the quarter-wavelength line connected to the auxiliary power amplifier is short-circuited, and its load impedance is 0. Since the output of the quarter-wave transmission line is connected to the first input of the transformer, the output of the main power amplifier is connected to the second input of the transformer and the output of the transformer is connected to the input of the output matching network, by adjusting the output matching network, the impedance seen by the port of the transformer to which the output matching network is connected is made to be 2Ropt.
Fig. 7 is a schematic diagram illustrating the high power region operation principle of the doherty power amplifier according to an embodiment of the present invention.
When the doherty power amplifier is configured to turn on the high power region, the main and auxiliary power amplifiers are turned on simultaneously at this time, and the output impedances of the main and auxiliary power amplifiers are Ropt at this time in consideration of the effect of load pulling. The output impedance of the quarter wavelength line is Ropt through the quarter wavelength line. Since the output of the quarter wave transmission line is connected to the first input of the transformer, the output of the main power amplifier is connected to the second input of the transformer and the output of the transformer is connected to the input of the output matching network, the impedance seen by the port of the transformer to which the output matching network is connected is adjusted to be 2Ropt.
While the back-end matching network of the traditional doherty amplifier needs to realize the impedance transformation from 50 ohm transformation to Ropt/2, the doherty power amplifier according to the embodiment of the invention reduces the impedance transformation ratio (from 50 ohm transformation to 2 Ropt) of the back-end matching network on the premise of realizing the function of the doherty power amplifier, and simultaneously places a quarter wavelength line in an auxiliary circuit, thereby avoiding the problem that the structural bandwidth is influenced by the larger impedance transformation in a low-power region and realizing the aim of improving the rollback efficiency in a broadband range.
Fig. 8 is a schematic diagram illustrating a doherty power amplifier according to another embodiment of the invention.
The doherty power amplifier according to an embodiment of the invention comprises a main path power amplifier and an auxiliary path power amplifier, a quarter-wavelength transmission line, a transformer, an output matching network, an input matching network and a phase shift network, and a main path impedance matching network.
Referring to fig. 8, a signal is input from an input terminal and supplied to an input matching network and a phase shift network, two signals (a main power amplifier signal and an auxiliary power amplifier signal) having a phase difference of 90 ° are generated through the input matching network and the phase shift network, and are supplied to the main power amplifier and the auxiliary power amplifier, respectively, wherein an output of the auxiliary power amplifier is connected to a quarter-wavelength transmission line and is connected to a first input terminal of a transformer through the quarter-wavelength transmission line. The output of the main power amplifier is connected to the second input of the transformer through a main impedance matching network. The output of the transformer is connected to the input of the output matching network and the amplified signal is output through the output matching network.
Compared with the traditional doherty power amplifier, the doherty power amplifier provided by the embodiment of the invention has the advantages that the main path impedance matching network is added after the main path power amplifier, so that the output impedance of the main path power amplifier in a low power region can be adjusted, the main path power amplifier enters a saturation region in advance, and the efficiency of larger (more than 6 dB) back-off power is improved.
According to the embodiment of the invention, the main path impedance matching network can be configured as a T-type impedance matching network and a pi-type impedance matching network.
According to an embodiment of the present invention, any one of the transistors in HBT, CMOS, BJT, biCMOS, gaN process may be used to implement the main path power amplifier and the auxiliary path power amplifier according to an embodiment of the present invention.
The doherty power amplifier according to an embodiment of the present invention can be applied to a 3G/4G/5G communication system, for example, the doherty power amplifier can be configured as a power amplifier for an N77 or N79 frequency band.
According to an embodiment of the present invention, the main and auxiliary power amplifiers may be configured as amplifier structures applied to 3G/4G/5G communication systems, for example, the main and auxiliary power amplifiers may be configured as power amplifiers of a cascode structure to increase circuit isolation and gain of the circuit.
Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to one skilled in the art. The disclosure is intended to embrace such alterations and modifications that fall within the scope of the appended claims.
Any description of the present invention should not be construed as implying that any particular element, step, or function is a necessary element to be included in the scope of the claims. The scope of patented subject matter is defined only by the claims.
Claims (10)
1. A broadband doherty power amplifier comprises a main path power amplifier, an auxiliary path power amplifier, a quarter-wavelength transmission line, a transformer, an output matching network, an input matching network and a phase shift network, wherein,
The input matching network and the phase shift network receive an input signal and generate a main path power amplifier signal and an auxiliary path power amplifier signal having a phase difference of 90 °;
The output of the auxiliary path power amplifier is connected to a quarter wavelength transmission line, and the auxiliary path power amplifier signal is received by the auxiliary path power amplifier and connected to a first input of a transformer through the quarter wavelength transmission line;
The main power amplifier receives the main power amplifier signal and outputs it to the second input of the transformer;
the output of the transformer is connected to the input of an output matching network and the amplified signal is output through the output matching network.
2. The wideband doherty power amplifier of claim 1 wherein the main path power amplifier is biased as a class AB power amplifier.
3. The wideband doherty power amplifier of claim 1 wherein the auxiliary path power amplifier is biased as a class C power amplifier.
4. The wideband doherty power amplifier of claim 1 further comprising a main path impedance matching network connected between an output of the main path power amplifier and a second input of the transformer.
5. The wideband doherty power amplifier of claim 1 wherein the main and auxiliary path power amplifiers are configured to have a best matching point impedance Ropt.
6. The wideband doherty power amplifier of claim 5 wherein the characteristic impedance of the quarter wave transmission line is configured as a best match point impedance Ropt.
7. The wideband doherty power amplifier of claim 5 wherein the input impedance of the output matching network is configured to be 2 times the best matching point impedance Ropt.
8. The wideband doherty power amplifier of claim 1 wherein the wideband doherty power amplifier is configured as a power amplifier for either the N77 or N79 frequency bands.
9. The wideband doherty power amplifier of claim 1 wherein the wideband doherty power amplifier is implemented by one of HBT, CMOS, BJT, biCMOS, gaN processes.
10. The wideband doherty power amplifier of claim 1 wherein the main and auxiliary path power amplifiers are configured as source-cascode power amplifiers.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410177987.8A CN118157594A (en) | 2024-02-08 | 2024-02-08 | Broadband doherty power amplifier |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410177987.8A CN118157594A (en) | 2024-02-08 | 2024-02-08 | Broadband doherty power amplifier |
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| CN118157594A true CN118157594A (en) | 2024-06-07 |
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| CN202410177987.8A Pending CN118157594A (en) | 2024-02-08 | 2024-02-08 | Broadband doherty power amplifier |
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