Differential Doherty Amplifier

Abstract

The utility model provides a differential Doherty amplifier, which comprises a quadrature device, a first peak amplifier, a second peak amplifier, a carrier differential amplifier and an output transformer, and is characterized in that the quadrature device is configured to generate two paths of orthogonal differential signals; the first peak amplifier receives-90-degree signals, and output signals of the first peak amplifier are connected to the first output end of the carrier differential amplifier through the first 90-degree phase shifter. The second peak amplifier receives a 90-degree signal, and an output signal of the second peak amplifier is connected to a second output end of the carrier differential amplifier through a second 90-degree phase shifter; the carrier differential amplifier receives a 0-degree signal and a 180-degree signal, a first output end of the carrier differential amplifier outputs the amplified 0-degree signal, and a second output end of the carrier differential amplifier outputs the amplified 180-degree signal; the output transformer is connected between the first output terminal and the second output terminal of the carrier differential amplifier, and outputs an amplified single-ended signal.

Description

Technical Field

[0001] The utility model relates to the field of wireless communications, and more specifically, to a differential Doherty amplifier with a symmetrical structure. Background Art

[0002] A power amplifier is a device that provides energy from a power supply to an AC signal, and plays a very important role in modern communications.

[0003] The Doherty amplifier is a commonly used amplifier in wireless communication systems. Its efficiency is optimized through the dynamic load modulation effect, which relies on the cooperation of two amplifiers working in different states to change the amplifier load, thereby optimizing the amplifier's back-off efficiency. More specifically, the carrier amplification path usually operates in Class AB mode, while the peak amplifier operates in Class C mode. At low power, only the carrier amplifier is turned on, and its load is at a higher position to maintain high efficiency. At high power, the peak amplifier is turned on and the carrier amplifier load is modulated to a lower position to produce high power output. Compared with ordinary amplifiers, this improves the power back-off efficiency of the amplifier in wireless communication applications.

[0004] In 5G communications, the power consumption problem caused by the power increase is becoming more and more obvious. At the same time, for non-constant envelope modulation, the peak-to-average power ratio (PAPR) is high, and the power amplifier works in the back-off mode most of the time. Therefore, for the power amplifier, the back-off efficiency becomes more important.

[0005] A conventional Doherty amplifier includes two amplifiers, a carrier amplifier and a peak amplifier. In a conventional Doherty amplifier, the carrier and peak amplifiers are of the same size, and their input signals are of the same size and 90 degrees out of phase. Among them, a 1 / 4 wavelength line or its LC equivalent circuit is placed after the carrier amplifier. When the peak amplifier is not turned on, the 1 / 4 wavelength line or its LC equivalent circuit converts the output impedance to high impedance to improve the back-off efficiency. For conventional Doherty amplifiers, on the one hand, for lower frequency broadband amplifiers, the 1 / 4 wavelength line occupies too large an area, and its LC equivalent circuit will reduce the matching bandwidth; on the other hand, even for high-frequency narrowband amplifiers, the 1 / 4 wavelength line occupies a smaller area, but due to the large high-frequency loss, it will also affect the saturation efficiency of the carrier amplifier, that is, the back-off efficiency of the Doherty amplifier. Therefore, a Doherty amplifier is needed that improves the back-off efficiency while taking into account the chip area.

[0006] In addition, if a conventional Doherty amplifier adopts a differential architecture, the two 1 / 4 wavelength lines will be close to each other, affecting their phase conversion and also affecting the layout of the output transformer. Its operating bandwidth will be reduced and the output matching loss of the carrier amplifier will increase. Utility Model Content

[0007] One aspect of the utility model provides a differential Doherty amplifier, comprising: an orthogonalizer, a first peak amplifier, a second peak amplifier, a carrier differential amplifier and an output transformer, characterized in that: the orthogonalizer is configured to receive an input signal and generate two orthogonal differential signals; the first peak amplifier receives a -90 degree signal in the two orthogonal differential signals, and its output signal is connected to the first output end of the carrier differential amplifier through a first 90 degree phase shifter; the second peak amplifier receives a 90 degree signal in the two orthogonal differential signals, and its output signal is connected to the second output end of the carrier differential amplifier through a second 90 degree phase shifter; the carrier differential amplifier receives a 0 degree signal and a 180 degree signal in the two orthogonal differential signals, and its first output end outputs an amplified 0 degree signal, and its second output end outputs an amplified 180 degree signal; the input end of the output transformer is connected between the first output end and the second output end of the carrier differential amplifier, and the output end of the output transformer is connected between the ground node and the output end of the differential Doherty amplifier.

[0008] One aspect of the present invention provides a differential Doherty amplifier, characterized in that the first 90-degree phase shifter and the second 90-degree phase shifter are configured as a 1 / 4 wavelength line.

[0009] One aspect of the utility model proposes a differential Doherty amplifier, characterized in that the first peak amplifier is configured as a two-stage power amplifier, a -90 degree signal is provided to a first driver-stage peak amplifier of the first peak amplifier, the amplified -90 degree signal is provided to the first power-stage peak amplifier through a first internal matching network, and then the signal is connected to the 0 degree signal line in the carrier differential amplifier through a first 90 degree phase shifter; the second peak amplifier is configured as a two-stage power amplifier, a 90 degree signal is provided to a second driver-stage peak amplifier of the second peak amplifier, the amplified 90 degree signal is provided to the second power-stage peak amplifier through a second internal matching network, and then the signal is connected to the 180 degree signal line in the carrier differential amplifier through a second 90 degree phase shifter.

[0010] One aspect of the utility model proposes a differential Doherty amplifier, characterized in that the carrier differential amplifier is configured as a two-stage power amplifier, a 0-degree signal and a 180-degree signal are provided as differential signals to a driving-stage carrier differential amplifier, the amplified 0-degree signal and the 180-degree signal are input to a power-stage carrier differential amplifier through an inter-stage transformer, and the power-stage carrier differential amplifier outputs an amplified 0-degree signal and an amplified 180-degree signal.

[0011] One aspect of the present invention provides a differential Doherty amplifier, characterized in that the carrier differential amplifier is configured between the first peak amplifier and the second peak amplifier.

[0012] One aspect of the utility model proposes a differential Doherty amplifier, characterized in that the orthogonal device is configured as an input orthogonal device based on a power divider, the input signal is converted into a first input signal and a second input signal through an input transformer, and the first input signal and the second input signal are differential signals; the first input signal is divided into a first power division signal and a second power division signal through a first power divider, the first power division signal is configured as a 0 degree signal, and the second power division signal is configured to be generated as a 90 degree signal through a first power division 90 degree phase shifter; and the second input signal is divided into a third power division signal and a fourth power division signal through a second power divider, the third power division signal is configured as a 180 degree signal, and the fourth power division signal is configured to be generated as a 270 degree signal through a second power division 90 degree phase shifter.

[0013] One aspect of the present invention provides a differential Doherty amplifier, characterized in that the first power divider and the second power divider are configured as Wilkinson power dividers.

[0014] One aspect of the utility model proposes a differential Doherty amplifier, characterized in that the orthogonal device is configured as an input orthogonal device based on a coupler, the input signal is converted into a first input signal and a second input signal through an input transformer, the first input signal and the second input signal are differential signals; the first input signal is divided into a 0 degree signal and a 90 degree signal through a first coupler, and the second input signal is divided into a 180 degree signal and a 270 degree signal through a second coupler.

[0015] One aspect of the present invention provides a differential Doherty amplifier, characterized in that the first coupler and the second coupler are configured as a hybrid coupler.

[0016] One aspect of the present invention provides a differential Doherty amplifier, characterized in that the output transformer is configured to be implemented on a substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram showing a differential Doherty power amplifier according to an embodiment of the utility model;

[0018] Figure 2 is a schematic diagram showing a differential Doherty power amplifier according to another embodiment of the utility model;

[0019] FIG. 3( a ) and FIG. 3( b ) are schematic diagrams showing an orthogonal device of a differential Doherty power amplifier according to an embodiment of the present invention; and

[0020] Figure 4 It is a schematic diagram showing a substrate implementation method of a differential Doherty power amplifier according to the utility model. DETAILED DESCRIPTION

[0021] Before the following detailed description, it may be advantageous to set forth the definitions of certain words and phrases used throughout the utility model document. The terms "coupling", "connection" and their derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with each other. The terms "transmission", "reception" and "communication" and their derivatives cover direct and indirect communication. The terms "include" and "comprising" and their derivatives refer to including but not limited to. The term "or" is inclusive, meaning and / or. The phrase "associated with..." and its derivatives refer to including, including within, interconnecting, containing, contained within, connecting or with...connecting, coupling or with...coupling, communicating with, cooperating, interweaving, parallel, approaching, binding or with...binding, having, having attributes, having a relationship or with...having a relationship, etc. The term "controller" refers to any device, system or part thereof that controls at least one operation. Such a controller can be implemented with hardware, or a combination of hardware and software and / or firmware. The functions associated with any particular controller can be centralized or distributed, whether local or remote. The phrase "at least one of", when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one of the items in the list may be required. For example, "at least one of A, B, C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, A and B and C.

[0022] Definitions for other specific words and phrases are provided throughout this document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior and future uses of such defined words and phrases.

[0023] In the present utility model document, the application combination of circuit blocks and the division of sub-circuit blocks are only used for illustration, and the application combination of circuit blocks and the division of sub-circuit blocks may have different modes without departing from the scope of the present disclosure.

[0024] The following discussion Figures 1 to 4 The various embodiments used to describe the principles of the present disclosure in this utility model document are only for illustration and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0025] At present, the conventional Doherty amplifier includes two amplifier modules, a carrier amplifier module and a peak amplifier module. In a conventional Doherty amplifier, the carrier and peak amplifier modules are of the same size, the input signals are of the same size, and their phases differ by 90 degrees. Among them, the 1 / 4 wavelength line or its LC equivalent circuit is placed after the carrier amplifier. When the peak amplifier module is not turned on, the 1 / 4 wavelength line or its LC equivalent circuit converts the output impedance to high impedance to improve the back-off efficiency.

[0026] Figure 1 is a schematic diagram showing a differential Doherty power amplifier according to an embodiment of the present utility model.

[0027] like Figure 1 As shown, the input signal passes through the orthogonal device to generate two orthogonal differential signals, which are respectively provided to the driver-level peak amplifier of the peak amplifier module and the driver-level carrier amplifier of the carrier amplifier module. The signal amplified by the driver-level peak amplifier of the peak amplifier module is transmitted to the power-level peak amplifier of the peak amplifier module through the first interstage transformer TR1 to be further amplified; the signal amplified by the driver-level carrier amplifier of the carrier amplifier module is transmitted to the power-level carrier amplifier of the carrier amplifier module through the second interstage transformer TR1' to be further amplified. Afterwards, the differential signals amplified by the power-level peak amplifier of the peak amplifier module pass through the 1 / 4 wavelength line to achieve a 90-degree phase shift, and the phase-shifted signals are provided to the output end of the power-level carrier amplifier of the carrier amplifier module to be combined with the output signal of the power-level carrier amplifier of the carrier amplifier module. Thereafter, the combined signal is converted into a single-ended signal through the output transformer TR2 and output.

[0028] In the above implementation, a 90-degree phase shift is achieved by using a 1 / 4 wavelength line. On the one hand, the area occupied by the 1 / 4 wavelength line is larger than that of other components, and for a differential amplifier, two 1 / 4 wavelength lines are required for phase conversion. While the area occupied is further increased, since the 1 / 4 wavelength lines are configured to be close to each other, it will affect the phase conversion. In addition, since its operating bandwidth will be reduced, the output matching loss of the carrier amplifier will increase. Therefore, it is necessary to consider a technical solution with a smaller occupied area and more accurate phase conversion.

[0029] Figure 2 is a schematic diagram showing a differential Doherty power amplifier according to another embodiment of the utility model.

[0030] refer to Figure 2 , the input signal is divided into four signals with a phase difference of 90 degrees after passing through the orthogonal device. For the carrier amplifier module, a differential circuit design is adopted, and the carrier amplifier module is set to be located in the middle of the chip. For the peak amplifier module, the amplifiers of the two signals with a phase difference of 180 degrees respectively adopt the design of single-ended amplifiers, and they are configured to be located on both sides of the chip, and finally connected to the output of the carrier amplifier module through a 90-degree phase shifter. Among them, the 90-degree phase shifter is configured as a 1 / 4 wavelength line. According to an embodiment of the utility model, the two sections of 1 / 4 wavelength lines can be configured to be far apart, so that they can be more easily integrated on the chip, and at the same time, their influence on the main transformer (output transformer) is also reduced.

[0031] Specifically, Figure 2As shown, the input signal passes through the orthogonal device to generate two orthogonal differential signals (i.e., four signals with a phase difference of 90 degrees), wherein the -90 degree signal is provided to the first driver-stage peak amplifier in the peak amplifier module, and the amplified -90 degree signal is provided to the first power-stage peak amplifier through the first internal matching network, and then the signal is connected to the 0 degree signal line in the power-stage carrier differential amplifier through the first 90 degree phase shifter; The 90-degree signal is provided to the second driver-stage peak amplifier in the peak amplifier module, and the amplified 90-degree signal is provided to the second power-stage peak amplifier through the second internal matching network, and then the signal is connected to the 180-degree signal line in the power-stage carrier differential amplifier through the second 90-degree phase shifter; the 0-degree first carrier signal and the 180-degree second carrier signal are provided as differential signals to the driver-stage carrier differential amplifier, and the amplified 0-degree signal and the 180-degree signal are input to the power-stage carrier differential amplifier through the first transformer TR1 (inter-stage transformer), wherein the 0-degree first carrier signal output by the power-stage carrier differential amplifier is connected to the -90-degree peak amplified signal after 90-degree phase shift, and is provided to the first input end of the second transformer TR2 (output transformer), the 180-degree second carrier amplified signal output by the power-stage carrier differential amplifier is connected to the 90-degree peak amplified signal after 90-degree phase shift, and is provided to the second input end of the second transformer TR2, the first output end of the second transformer TR2 outputs the RF amplified signal, and its second output end is grounded.

[0032] By configuring the carrier amplifier module as a single differential amplifier, configuring the peak amplifier module as a first peak amplifier branch and a second peak amplifier branch for single-ended amplification, and configuring the carrier differential amplifier module between the first peak amplifier branch and the second peak amplifier branch, the two 90-degree phase shifters configured in the peak amplifier branch can be configured to be relatively far apart, and the influence of the 90-degree phase shifter on the main transformer (the second transformer) can be reduced.

[0033] Although the above example shows an example of implementing the Doherty amplifier by a two-stage amplifier, those skilled in the art should understand that the Doherty power amplifier of the present invention can also be implemented by a single-stage amplifier. When a single-stage amplifier is used, except that an internal matching unit and an inter-stage transformer are no longer required, other structures are the same as those of the two-stage amplifier, and will not be described in detail here.

[0034] Those skilled in the art should understand that the structure of the present invention can be applied to Doherty power amplifiers implemented with differential or cascode structures of various CMOS, HBT, and SiGe processes.

[0035] FIG. 3( a ) and FIG. 3( b ) are schematic diagrams showing an orthogonal device of a differential Doherty power amplifier according to an embodiment of the present invention.

[0036] Referring to FIG. 3 (a), the orthogonal device of the differential Doherty power amplifier according to the embodiment of the utility model can be configured as a transformer-based input orthogonal device. The input signal is converted into two differential signals through the input transformer TR1, namely, a first input signal of 0 degrees and a second input signal of 180 degrees. Thereafter, the first input signal is divided into two signals through a power divider, one of which is a first carrier input signal of 0 degrees, and the other of which is converted into a first peak input signal of 90 degrees through a 90-degree phase shifter; the second input signal is divided into two signals through a power divider, one of which is a second carrier input signal of 180 degrees, and the other of which is converted into a second peak input signal of 270 degrees through a 90-degree phase shifter. Wherein, the power divider can be configured as a Wilkinson power divider.

[0037] Referring to FIG. 3 (b), the orthogonal device of the differential Doherty power amplifier according to the embodiment of the present invention can be configured as a transformer-based input orthogonal device. The input signal is converted into two differential signals through the input transformer TR1, namely, a first input signal of 0 degrees and a second input signal of 180 degrees. Thereafter, the first input signal is divided into two signals through the first coupler, one of which is a first carrier input signal of 0 degrees, and the other is a first peak input signal of 90 degrees; the second input signal is divided into two signals through the second coupler, one of which is a second carrier input signal of 180 degrees, and the other is converted into a second peak input signal of 270 degrees through a 90-degree phase shifter. Wherein, the first coupler and the second coupler can be configured as hybrid couplers.

[0038] Those skilled in the art should understand that what are shown in FIG. 3( a ) and FIG. 3( b ) are merely examples of the orthogonal device according to the present invention, and corresponding modifications may be made thereto without departing from the scope of the present invention.

[0039] Figure 4 It is a schematic diagram showing a substrate implementation method of a differential Doherty power amplifier according to the utility model.

[0040] refer to Figure 4By configuring the carrier differential amplifier module between the first peak amplifier branch and the second peak amplifier branch, the interstage transformer and the output transformer can be configured as a symmetrical structure. According to an embodiment of the present invention, the output transformer can be configured to be implemented on a substrate. According to this configuration, the chip layout can be completely symmetrical with the output transformer, so that the carrier amplifier module and the peak amplifier module do not affect each other, and the module design in which the chip is located is more flexible.

[0041] Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to encompass such changes and modifications as fall within the scope of the appended claims.

[0042] Any description in the utility model should not be understood as implying that any particular element, step or function is an essential element that must be included in the scope of the claims. The scope of the utility model subject matter is limited only by the claims.

Claims

1. A differential Doherty amplifier, comprising: An orthogonal device, a first peak amplifier, a second peak amplifier, a carrier differential amplifier and an output transformer, characterized in that: The orthogonal device is configured to receive an input signal and generate two orthogonal differential signals; The first peak amplifier receives a -90 degree signal in two orthogonal differential signals, and its output signal is connected to the first output terminal of the carrier differential amplifier through a first 90 degree phase shifter; The second peak amplifier receives a 90-degree signal in the two orthogonal differential signals, and its output signal is connected to the second output terminal of the carrier differential amplifier through a second 90-degree phase shifter; The carrier differential amplifier receives a 0-degree signal and a 180-degree signal in two orthogonal differential signals, and outputs an amplified 0-degree signal at a first output terminal and outputs an amplified 180-degree signal at a second output terminal; An input terminal of the output transformer is connected between the first output terminal and the second output terminal of the carrier differential amplifier, and an output terminal of the output transformer is connected between a ground node and an output terminal of the differential Doherty amplifier.

2. The differential Doherty amplifier according to claim 1, characterized in that: The first 90 degree phase shifter and the second 90 degree phase shifter are configured as 1 / 4 wavelength lines.

3. The differential Doherty amplifier according to claim 1, wherein: The first peak amplifier is configured as a two-stage power amplifier, the -90 degree signal is provided to the first driver stage peak amplifier of the first peak amplifier, the amplified -90 degree signal is provided to the first power stage peak amplifier through the first internal matching network, and then the signal is connected to the 0 degree signal line in the carrier differential amplifier through the first 90 degree phase shifter; The second peak amplifier is configured as a two-stage power amplifier, the 90-degree signal is provided to the second driver-stage peak amplifier of the second peak amplifier, the amplified 90-degree signal is provided to the second power-stage peak amplifier through a second internal matching network, and then the signal is connected to the 180-degree signal line in the carrier differential amplifier through a second 90-degree phase shifter.

4. The differential Doherty amplifier according to claim 1, wherein: The carrier differential amplifier is configured as a two-stage power amplifier, the 0-degree signal and the 180-degree signal are provided as differential signals to the driving-stage carrier differential amplifier, the amplified 0-degree signal and the 180-degree signal are input to the power-stage carrier differential amplifier through an inter-stage transformer, and the power-stage carrier differential amplifier outputs the amplified 0-degree signal and the amplified 180-degree signal.

5. The differential Doherty amplifier according to claim 1, wherein: The carrier differential amplifier is configured between the first peak amplifier and the second peak amplifier.

6. The differential Doherty amplifier according to claim 1, characterized in that: The orthogonal device is configured as an input orthogonal device based on a power divider, and the input signal is converted into a first input signal and a second input signal through an input transformer, and the first input signal and the second input signal are differential signals; The first input signal is divided into a first power division signal and a second power division signal by a first power division device, the first power division signal is configured as a 0 degree signal, and the second power division signal is configured to be generated as a 90 degree signal by a first power division 90 degree phase shifter; and The second input signal is divided into a third power division signal and a fourth power division signal by the second power divider, the third power division signal is configured as a 180 degree signal, and the fourth power division signal is configured to be generated as a 270 degree signal by the second power division 90 degree phase shifter.

7. The differential Doherty amplifier according to claim 6, characterized in that: The first power divider and the second power divider are configured as Wilkinson power dividers.

8. The differential Doherty amplifier according to claim 1, wherein: The orthogonal device is configured as a coupler-based input orthogonal device, the input signal is converted into a first input signal and a second input signal through an input transformer, and the first input signal and the second input signal are differential signals; The first input signal is divided into a 0 degree signal and a 90 degree signal by a first coupler, and The second input signal is divided into a 180-degree signal and a 270-degree signal by a second coupler.

9. The differential Doherty amplifier according to claim 8, characterized in that: The first coupler and the second coupler are configured as a hybrid coupler.

10. The differential Doherty amplifier according to claim 1, wherein: The output transformer is configured to be implemented on a substrate.

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