Low-voltage broadband radio frequency power amplifier

Abstract

The utility model provides a low-voltage broadband radio frequency power amplifier. The low-voltage broadband radio frequency power amplifier comprises an input quadrature device, a driving stage amplifier, an interstage transformer, a power stage peak amplifier, a power stage carrier amplifier, a 90-degree phase shifter and an output transformer, wherein a first input signal and a second input signal are generated by an input quadrature, the first input signal for generating a first carrier signal and a second carrier signal, the first carrier signal being provided to a first impedance combining point via a first carrier 90-degree phase shifter, and the second carrier signal being provided to a second impedance combining point via a second carrier 90-degree phase shifter. A second carrier signal is provided to a second impedance combining point via a second carrier 90-degree phase shifter; the second input signal is used to generate a first peak signal and a second peak signal, the first peak signal being provided to a first impedance combining point via a first peak 90-degree phase shifter and a second peak 90-degree phase shifter, and a second peak signal is provided to a second impedance combining point via a third peak 90-degree phase shifter and a fourth peak 90-degree phase shifter.

Description

Technical Field

[0001] The utility model relates to the field of wireless communications, and more specifically, to a low-voltage broadband radio frequency power amplifier for improving bandwidth. Background Art

[0002] The power amplifier is an important component in modern communications. It is a device that provides the energy provided by the power supply to the AC signal. The Doherty amplifier is a commonly used amplifier in wireless communication systems. Its efficiency is optimized through the dynamic load modulation effect. It 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 amplifier 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.

[0003] In mobile phone 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 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.

[0004] In addition, since 5G communications require a communication frequency band with a larger bandwidth, it is necessary to consider the bandwidth of the RF power amplifier. At the same time, in order to meet power consumption and process requirements, a low-voltage broadband RF power amplifier is required. Utility Model Content

[0005] In one aspect, the utility model provides a low-voltage broadband radio frequency power amplifier, comprising: an input orthogonalizer, a driver stage amplifier, an interstage transformer, a power stage peak amplifier, a power stage carrier amplifier, a 90-degree phase shifter, and an output transformer, characterized in that: the driver stage amplifier is configured to include a first driver stage amplifier and a second driver stage amplifier; the interstage transformer is configured to include a first interstage transformer and a second interstage transformer; the 90-degree phase shifter includes a first carrier 90-degree phase shifter, a second carrier 90-degree phase shifter, a first peak 90-degree phase shifter, a second peak 90-degree phase shifter, a third peak 90-degree phase shifter, and a fourth peak 90-degree phase shifter; the power stage carrier amplifier includes a first carrier amplifier and a second carrier amplifier; the power stage peak amplifier includes a first peak amplifier and a second peak amplifier; the input orthogonalizer is configured to separate the input signal into a first input signal and a second input signal, the first input signal and the second input signal being orthogonal signals; the first driver stage amplifier amplifies the first input signal, and the amplified first input signal is transmitted to the first input stage amplifier. The first interstage transformer generates a first carrier signal and a second carrier signal, the first carrier signal is provided to a first impedance combining point through a first carrier amplifier via a first carrier 90-degree phase shifter, and the second carrier signal is provided to a second impedance combining point through a second carrier amplifier via a second carrier 90-degree phase shifter; the second driver stage amplifier amplifies the second input signal, and the amplified second input signal generates a first peak signal and a second peak signal through the second interstage transformer, the first peak signal is provided to the first impedance combining point through a first peak amplifier via a first peak 90-degree phase shifter and a second peak 90-degree phase shifter, and the second peak signal is provided to the second impedance combining point through a third peak 90-degree phase shifter and a fourth peak 90-degree phase shifter after being amplified by the second peak amplifier; the input end of the output transformer is arranged between the first impedance combining point and the second impedance combining point, and one end of its output end is grounded, and the other end of its output is output as the output of the Doherty power amplifier.

[0006] One aspect of the utility model provides a low-voltage broadband radio frequency power amplifier, characterized in that the input orthogonal device is configured to include a power divider and an input 90-degree phase shifter.

[0007] One aspect of the utility model provides a low-voltage broadband radio frequency power amplifier, characterized in that the power divider comprises a Wilkinson power divider, and the input 90-degree phase shifter is configured as a 1 / 4 wavelength line.

[0008] One aspect of the present invention provides a low-voltage broadband radio frequency power amplifier, characterized in that the first driver stage amplifier and the second driver stage amplifier are configured as single-ended amplifiers.

[0009] One aspect of the utility model provides a low-voltage broadband RF power amplifier, characterized in that it also includes an input transformer, the input transformer includes a first input transformer and a second input transformer, and the first driver stage amplifier and the second driver stage amplifier are configured as differential amplifiers.

[0010] One aspect of the utility model provides a low-voltage broadband RF power amplifier, characterized in that the first input transformer is configured to change the first input signal into a differential signal, and the first driver stage amplifier amplifies the differential first input signal; the second input transformer is configured to change the second input signal into a differential signal, and the second driver stage amplifier amplifies the differential second input signal.

[0011] One aspect of the utility model provides a low-voltage broadband radio frequency power amplifier, characterized in that the carrier amplifier or the peak amplifier includes one of an HBT amplifier, a CMOS amplifier, a SiGe amplifier, a single-ended amplifier or a Cascode structure power amplifier.

[0012] One aspect of the present invention provides a low-voltage broadband radio frequency power amplifier, characterized in that the carrier amplifier operates in a Class A or Class AB state, and the peak amplifier operates in a Class C state.

[0013] One aspect of the present invention provides a low-voltage broadband radio frequency power amplifier, characterized in that the output transformer is configured on a substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram showing a conventional differential Doherty power amplifier;

[0015] Figure 2 is a schematic diagram showing a low voltage broadband Doherty power amplifier according to an embodiment of the utility model; and

[0016] Figure 3 is a schematic diagram showing a low-voltage broadband Doherty power amplifier according to yet another embodiment of the utility model. DETAILED DESCRIPTION

[0017] 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.

[0018] 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.

[0019] 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.

[0020] The following discussion Figures 1 to 3 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.

[0021] At present, the 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, 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 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. On the one hand, for broadband amplifiers with lower frequencies, 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 also affects the saturation efficiency of the carrier amplifier, that is, the back-off efficiency of the Doherty amplifier.

[0022] Figure 1 is a schematic diagram showing a conventional differential Doherty power amplifier.

[0023] like Figure 1 As shown, the differential Doherty power amplifier includes: an input orthogonalizer, an input transformer, a driver stage differential amplifier, an inter-stage transformer, a power stage peak amplifier, a power stage carrier amplifier, a 90-degree phase shifter, and an output transformer.

[0024] The input signal is separated into two mutually orthogonal signals, i.e., a first input signal and a second input signal, by an input orthogonal device. The input orthogonal device is configured as a combination of a power divider and an input 90-degree phase shifter, wherein the power divider includes a Wilkinson power divider, and the input 90-degree phase shifter is configured as a 1 / 4 wavelength line.

[0025] The first input signal is transformed into two differential signals through the first input transformer, the differential signals are amplified by the first driver stage differential amplifier, a first peak signal and a second peak signal are generated by the first inter-stage transformer, the first peak signal is provided to the first impedance combining point through the first peak amplifier, and the second peak signal is provided to the second impedance combining point through the second peak amplifier.

[0026] The second input signal is transformed into two differential signals through the second input transformer, the differential signals are amplified by the second driver stage differential amplifier, and the first carrier signal and the second carrier signal are generated through the second interstage transformer, the first carrier signal is amplified by the first carrier amplifier and provided to the first impedance junction via the first 90-degree phase shifter, and the second carrier signal is amplified by the second carrier amplifier and provided to the second impedance junction via the second 90-degree phase shifter. The 90-degree phase shifter is configured as a 1 / 4 wavelength line.

[0027] The input end of the output transformer is arranged between the first impedance combining point and the second impedance combining point, one end of its output end is grounded, and the other end of its output is output as the output of the Doherty power amplifier to convert the differential signal into a single-ended output.

[0028] For a conventional Doherty amplifier, if a differential architecture is used, such as Figure 1 As shown, the output transformer converts the load 50Ohm impedance to R impedance. When the peak amplifier is not turned on, the load of the carrier amplifier is converted from the 1 / 4 wavelength line or its LC equivalent circuit to the high impedance 4*R to improve the back-off efficiency; when the peak amplifier is fully turned on, the loads of the carrier amplifier and the peak amplifier are both 2*R. According to the amplifier principle, when the supply voltage is low and the output power is high, a lower load of 2*R is required. At the same time, the output transformer impedance conversion ratio is higher, the bandwidth becomes narrower, and it cannot meet the application requirements of broadband amplifiers.

[0029] Figure 2 is a schematic diagram showing a low-voltage broadband Doherty power amplifier according to an embodiment of the utility model.

[0030] refer to Figure 2 According to an embodiment of the utility model, the low-voltage broadband Doherty power amplifier includes: an input orthogonalizer, an input transformer, a driver stage differential amplifier, an interstage transformer, a power stage peak amplifier, a power stage carrier amplifier, a 90-degree phase shifter, and an output transformer.

[0031] The input signal is separated into two mutually orthogonal signals, i.e., a first input signal and a second input signal, by an input orthogonal device. The input orthogonal device is configured as a combination of a power divider and an input 90-degree phase shifter, the power divider includes a Wilkinson power divider, and the input 90-degree phase shifter is configured as a 1 / 4 wavelength line.

[0032] The first input signal is transformed into two differential signals through the first input transformer, the differential signals are amplified by the first driver stage differential amplifier, and the first carrier signal (0 degree signal) and the second carrier signal (180 degree signal) are generated by the first inter-stage transformer. The first carrier signal is provided to the first impedance combining point through the first carrier amplifier via the first carrier 90 degree phase shifter, and the second carrier signal is provided to the second impedance combining point through the second carrier amplifier via the second carrier 90 degree phase shifter.

[0033] The second input signal is changed into two differential signals through the second input transformer, the differential signals are amplified by the second driver stage differential amplifier, and the first peak signal (90 degree signal) and the second peak signal (270 degree signal) are generated through the second interstage transformer, the first peak signal is amplified by the first peak amplifier and provided to the first impedance junction via the first peak 90 degree phase shifter and the second peak 90 degree phase shifter, and the second peak signal is amplified by the second peak amplifier and provided to the second impedance junction via the third peak 90 degree phase shifter and the fourth peak 90 degree phase shifter. The 90 degree phase shifter is configured as a 1 / 4 wavelength line.

[0034] The input end of the output transformer is arranged between the first impedance combining point and the second impedance combining point, one end of its output end is grounded, and the other end of its output is output as the output of the Doherty power amplifier to convert the differential signal into a single-ended output.

[0035] like Figure 2 As shown, when the peak amplifier is not turned on, the load of the carrier amplifier is converted from the 1 / 4 wavelength line or its LC equivalent circuit to a high impedance of 2*R. When the peak amplifier is fully turned on, the loads of the carrier amplifier and the peak amplifier are both R. According to the amplifier principle, when the output transformer provides the same load impedance R, the output power is doubled compared to the conventional Doherty amplifier. Alternatively, while maintaining the same load impedance R and output power, the required supply voltage will be greatly reduced, thus achieving the requirements of a low-voltage amplifier. At the same time, in a conventional Doherty amplifier, the load impedance conversion ratio of the carrier amplifier is 4, while the load impedance conversion ratio of the carrier amplifier in this patent is 2, which effectively improves the amplifier bandwidth.

[0036] According to an embodiment of the utility model, the peak amplifier is composed of two 1 / 4 wavelength lines for impedance conversion, which can be integrated on a chip or a substrate according to actual conditions. Compared with a conventional Doherty amplifier, it slightly increases the output power loss of the peak amplifier and reduces the power added efficiency (PAE). However, by integrating the 1 / 4 wavelength line on the substrate, it is helpful to reduce the interference caused by the 1 / 4 wavelength line to the amplifier circuit. According to an embodiment of the utility model, the output transformer can be configured on the substrate to increase the flexibility of the design.

[0037] Those skilled in the art should understand that the structure of the present invention can be applied to various types of power amplification unit circuits. For example, the power amplifier can include an HBT amplifier, a CMOS amplifier, a SiGe amplifier, a single-ended amplifier, a differential amplifier, or an amplifier with a Cascode structure.

[0038] Figure 3is a schematic diagram showing a low-voltage broadband Doherty power amplifier according to yet another embodiment of the utility model.

[0039] refer to Figure 3 According to an embodiment of the utility model, the low-voltage broadband Doherty power amplifier includes: an input orthogonalizer, a driver stage amplifier, an interstage transformer, a power stage peak amplifier, a power stage carrier amplifier, a 90-degree phase shifter, and an output transformer.

[0040] The input signal is separated into two mutually orthogonal signals through an input orthogonalizer, namely, a first input signal and a second input signal.

[0041] The first input signal is amplified by the first driver stage amplifier, and the first carrier signal (0 degree signal) and the second carrier signal (180 degree signal) are generated by the first interstage transformer, the first carrier signal is provided to the first impedance junction through the first carrier amplifier via the first carrier 90 degree phase shifter, and the second carrier signal is provided to the second impedance junction through the second carrier amplifier via the second carrier 90 degree phase shifter. One end of the input end of the first interstage transformer is connected to the reference voltage VCC1, and the other end thereof is connected to the output end of the first driver stage amplifier.

[0042] The second input signal is amplified by the second driver stage amplifier, and the first peak signal (90 degree signal) and the second peak signal (270 degree signal) are generated by the second interstage transformer. The first peak signal is amplified by the first peak amplifier and provided to the first impedance junction via the first peak 90 degree phase shifter and the second peak 90 degree phase shifter, and the second peak signal is amplified by the second peak amplifier and provided to the second impedance junction via the third peak 90 degree phase shifter and the fourth peak 90 degree phase shifter. One end of the input end of the second interstage transformer is connected to the reference voltage VCC1, and the other end thereof is connected to the output end of the second driver stage amplifier. And the 90 degree phase shifter is configured as a 1 / 4 wavelength line.

[0043] The input end of the output transformer is arranged between the first impedance combining point and the second impedance combining point, one end of its output end is grounded, and the other end of its output is output as the output of the Doherty power amplifier to convert the differential signal into a single-ended output.

[0044] According to an embodiment of the present invention, the driver stage amplifier is configured as a single-ended architecture to reduce the number of transformers on a chip.

[0045] According to an embodiment of the present utility model, the carrier amplifier operates in a Class A or Class AB state, and the peak amplifier operates in a Class C state.

[0046] 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.

[0047] 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 low voltage broadband radio frequency power amplifier, comprising: An input orthogonal device, a driver stage amplifier, an interstage transformer, a power stage peak amplifier, a power stage carrier amplifier, a 90 degree phase shifter, and an output transformer, characterized in that: The driver stage amplifier is configured to include a first driver stage amplifier and a second driver stage amplifier; The interstage transformer is configured to include a first interstage transformer and a second interstage transformer; The 90-degree phase shifter includes a first carrier 90-degree phase shifter, a second carrier 90-degree phase shifter, a first peak 90-degree phase shifter, a second peak 90-degree phase shifter, a third peak 90-degree phase shifter, and a fourth peak 90-degree phase shifter; The power stage carrier amplifier includes a first carrier amplifier and a second carrier amplifier; The power stage peak amplifier includes a first peak amplifier and a second peak amplifier; The input orthogonalizer is configured to separate the input signal into a first input signal and a second input signal, wherein the first input signal and the second input signal are orthogonal signals; The first driver stage amplifier amplifies the first input signal, and the amplified first input signal generates a first carrier signal and a second carrier signal through the first interstage transformer, the first carrier signal is provided to a first impedance junction through the first carrier amplifier via a first carrier 90-degree phase shifter, and the second carrier signal is provided to a second impedance junction through the second carrier amplifier via a second carrier 90-degree phase shifter; The second driver stage amplifier amplifies the second input signal, and the amplified second input signal generates a first peak signal and a second peak signal through the second inter-stage transformer, the first peak signal is amplified by the first peak amplifier and provided to the first impedance junction via the first peak 90-degree phase shifter and the second peak 90-degree phase shifter, and the second peak signal is amplified by the second peak amplifier and provided to the second impedance junction via the third peak 90-degree phase shifter and the fourth peak 90-degree phase shifter; The input end of the output transformer is arranged between the first impedance combining point and the second impedance combining point, one end of the output end is grounded, and the other end of the output is output as the output of the Doherty power amplifier.

2. The low voltage broadband radio frequency power amplifier according to claim 1, characterized in that: The input quadrature is configured to include a power divider and an input 90 degree phase shifter.

3. The low voltage broadband radio frequency power amplifier according to claim 2, characterized in that: The power divider comprises a Wilkinson power divider, and the input 90 degree phase shifter is configured as a 1 / 4 wavelength line.

4. The low voltage broadband radio frequency power amplifier according to claim 1, characterized in that: The first driver stage amplifier and the second driver stage amplifier are configured as single-ended amplifiers.

5. The low voltage broadband radio frequency power amplifier according to claim 1, characterized in that: Also included is an input transformer, the input transformer comprising a first input transformer and a second input transformer, The first driver stage amplifier and the second driver stage amplifier are configured as differential amplifiers.

6. The low-voltage broadband radio frequency power amplifier according to claim 5, characterized in that: The first input transformer is configured to transform the first input signal into a differential signal, and the first driver amplifier amplifies the differential first input signal; The second input transformer is configured to transform the second input signal into a differential signal, and the second driver stage amplifier amplifies the differential second input signal.

7. The low voltage broadband radio frequency power amplifier according to claim 1, characterized in that: The carrier amplifier or the peak amplifier includes one of an HBT amplifier, a CMOS amplifier, a SiGe amplifier, a single-ended amplifier or a Cascode structure power amplifier.

8. The low voltage broadband radio frequency power amplifier according to claim 1, characterized in that: The carrier amplifier operates in a Class A or Class AB state, and the peak amplifier operates in a Class C state.

9. The low voltage broadband radio frequency power amplifier according to claim 1, characterized in that: The output transformer is disposed on a substrate.

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