Envelope tracking circuit and related power amplifier system

Abstract

An envelope tracking circuit and an associated power amplifier system are provided. In one aspect, the ET circuit is configured to generate a first number of ET modulation voltages based on a second number of target voltages, and to output the first number of ET modulation voltages via a third number of voltage outputs. In another aspect, the ET circuit can be disposed in a power amplifier system, the power amplifier system comprising a transceiver circuit and a plurality of power amplifier circuits. In the example discussed herein, the ET circuit can receive the second number of target voltages from the transceiver circuit, and provide the first number of ET modulation voltages to the power amplifier circuit for amplifying a radio frequency (RF) signal. By disposing the ET circuit in the power amplifier system, ET power management can be flexibly enabled based on any number of transceiver circuits and for any number of power amplifier circuits.

Description

[0001] Related Applications

[0002] This application claims the benefit of provisional patent application serial number 62 / 625,137, filed February 1, 2018, the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0003] The technology of the present disclosure generally relates to envelope tracking power amplifier circuits and systems. Background Art

[0004] Mobile communication devices are becoming increasingly common in today's society to provide wireless communication services. The popularity of these mobile communication devices is driven in part by the many functions that are enabled on these devices today. Increased processing power in these devices means that mobile communication devices have evolved from being mere communication tools to sophisticated mobile multimedia centers that can enhance the user experience.

[0005] The redefined user experience requires higher data rates provided by wireless communication technologies such as fifth generation new radio (5G-NR) and Wi-Fi, which generally operates in a higher frequency spectrum. In this regard, mobile communications can use a variety of different transceiver circuits to simultaneously support a variety of different wireless communication technologies. In order to achieve higher data rates and enhanced robustness in a higher frequency spectrum, mobile communication devices can also use multiple antennas to implement multiple input multiple output (MIMO) and / or beamforming operations. Before transmitting a radio frequency (RF) signal from multiple antennas, a complex power amplifier circuit can be used to increase the output power of the RF signal (e.g., to maintain sufficient energy per bit). However, the increase in the number of transceiver circuits, antennas, and power amplifier circuits will result in increased power consumption in the mobile communication device, which will impair the overall performance and user experience.

[0006] Envelope tracking (ET) is a power management technique that aims to improve the efficiency level of power amplifier circuits to help reduce the power consumption of mobile communication devices. As the name implies, the ET system receives an ET target voltage that can be generated by different transceiver circuits, and generates an ET modulation voltage based on the ET target voltage. Therefore, the power amplifier circuit can be configured to amplify the RF signal based on the ET modulation voltage. In this regard, it may be desirable to adopt a highly flexible power management architecture to support different transceiver circuits, antennas, and power amplifier circuits in mobile communication devices to improve efficiency and performance. Summary of the invention

[0007] Embodiments of the present disclosure relate to envelope tracking (ET) circuits and associated power amplifier systems. In one aspect, the ET circuit is configured to generate a first number of ET modulation voltages based on a second number of target voltages, and to output the first number of ET modulation voltages via a third number of voltage outputs. On the other hand, the ET circuit can be provided in a power amplifier system that includes a transceiver circuit and a plurality of power amplifier circuits. In the examples discussed herein, the ET circuit can receive a second number of target voltages from the transceiver circuit, and provide the first number of ET modulation voltages to a power amplifier circuit for amplifying a radio frequency (RF) signal. By providing the ET circuit in the power amplifier system, ET power management can be flexibly enabled based on any number of transceiver circuits and for any number of power amplifier circuits.

[0008] In one aspect, an ET circuit is provided. The ET circuit includes an ET voltage circuit. The ET voltage circuit includes a first number of tracker circuits configured to generate a first number of ET modulation voltages. The ET voltage circuit also includes a second number of voltage inputs configured to receive a second number of target voltages. The ET voltage circuit also includes a third number of voltage outputs configured to output the first number of ET modulation voltages. The ET circuit also includes a control circuit. The control circuit is configured to couple a selected number of tracker circuits from the first number of tracker circuits to a selected number of voltage inputs from the second number of voltage inputs. The selected number of tracker circuits is configured to receive a selected number of target voltages from the second number of target voltages via the selected number of voltage inputs. The selected number of tracker circuits is also configured to generate a selected number of ET modulation voltages from the first number of ET modulation voltages based on the selected number of target voltages. The control circuit is also configured to selectively provide the selected number of ET modulation voltages to the third number of voltage outputs.

[0009] In another aspect, a power amplifier system is provided. The power amplifier system includes an ET circuit. The ET circuit includes an ET voltage circuit. The ET voltage circuit includes a first number of tracker circuits configured to generate a first number of ET modulation voltages. The ET voltage circuit also includes a second number of voltage inputs configured to receive a second number of target voltages. The ET voltage circuit also includes a third number of voltage outputs configured to output the first number of ET modulation voltages. The ET circuit also includes a control circuit. The control circuit is configured to couple a selected number of tracker circuits in the first number of tracker circuits to a selected number of voltage inputs in the second number of voltage inputs. The selected number of tracker circuits is configured to receive a selected number of target voltages in the second number of target voltages via the selected number of voltage inputs. The selected number of tracker circuits is further configured to generate a selected number of ET modulation voltages in the first number of ET modulation voltages based on the selected number of target voltages. The control circuit is further configured to selectively provide the selected number of ET modulation voltages to the third number of voltage outputs. The power amplifier system also includes a plurality of power amplifier circuits coupled to the third number of voltage outputs, each power amplifier circuit being configured to amplify an RF signal based on an ET modulation voltage in the first number of ET modulation voltages.

[0010] Those skilled in the art will understand the scope of the present disclosure and recognize additional aspects of the present disclosure after reading the following detailed description of the preferred embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate several aspects of the disclosure, and together with the description, serve to explain the principles of the disclosure.

[0012] Figure 1 is a schematic diagram of an exemplary envelope tracking (ET) circuit that can be flexibly configured to generate a first number of ET modulation voltages based on a second number of target voltages and output the first number of ET modulation voltages via a third number of voltage outputs;

[0013] Figure 2 Yes Figure 1 A schematic diagram of an exemplary illustration of an output switch circuit in an ET circuit, the output switch circuit being configured to output a smaller number of ET modulated voltages to a larger number of voltage outputs;

[0014] Figure 3 is configured according to one embodiment of the present disclosure to include Figure 1 A schematic diagram of an exemplary power amplifier system of an ET circuit;

[0015] Figure 4According to another embodiment of the present disclosure, a Figure 1 A schematic diagram of an exemplary power amplifier system of an ET circuit;

[0016] Figure 5 is a schematic diagram of an exemplary power amplifier system according to one embodiment of the present disclosure, the power amplifier system being configured to include at least two Figure 1 ET circuit; and

[0017] Figure 6 is a schematic diagram of an exemplary power amplifier system according to another embodiment of the present disclosure, the power amplifier system being configured to include at least two Figure 1 ET circuit. DETAILED DESCRIPTION

[0018] The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments, and illustrate the best mode for practicing the embodiments. After reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure, and will recognize the application of these concepts not specifically proposed herein. It should be understood that these concepts and applications are within the scope of the present disclosure and the appended claims.

[0019] It should be understood that although the terms first, second, etc. may be used in this article to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present disclosure, the first element may be named as the second element, and similarly, the second element may be named as the first element. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0020] It should be understood that when an element such as a layer, region, or substrate is referred to as being "on" or extending "on" another element, it may be directly on or directly extending to another element, or there may also be an intervening element. In contrast, when an element is referred to as "directly on" another element or extending "directly" to another element, there is no intervening element. Similarly, it should be understood that when an element such as a layer, region, or substrate is referred to as being "on" or extending "on another element", it may be directly on or directly on another element, or there may also be an intervening element. In contrast, when an element is referred to as extending "directly on" or "directly on" another element, there is no intervening element. It should also be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to another element, or there may be an intervening element. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there is no intervening element.

[0021] Relative terms such as "below" or "above" or "up" or "lower" or "horizontal" or "vertical" may be used herein to describe the relationship of one element, layer or region to another element, layer or region illustrated in the figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0022] The terms used herein are only used for the purpose of describing specific embodiments, and are not intended to limit the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms "one" and "said" are intended to include plural forms as well. It should also be understood that when used herein, the term "comprising" indicates the presence of the features, wholes, steps, operations, elements and / or parts, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, parts and / or their groups.

[0023] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. It should also be understood that the terms used herein should be interpreted as having the same meaning as they have in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense, unless explicitly defined in this article.

[0024] Embodiments of the present disclosure relate to envelope tracking (ET) circuits and associated power amplifier systems. In one aspect, the ET circuit is configured to generate a first number of ET modulation voltages based on a second number of target voltages, and to output the first number of ET modulation voltages via a third number of voltage outputs. On the other hand, the ET circuit can be provided in a power amplifier system that includes a transceiver circuit and a plurality of power amplifier circuits. In the examples discussed herein, the ET circuit can receive a second number of target voltages from the transceiver circuit, and provide the first number of ET modulation voltages to a power amplifier circuit for amplifying a radio frequency (RF) signal. By providing the ET circuit in the power amplifier system, ET power management can be flexibly enabled based on any number of transceiver circuits and for any number of power amplifier circuits.

[0025] in this regard, Figure 1 1 is a schematic diagram of an exemplary ET circuit 10 that can be flexibly configured to generate a first number of ET modulation voltages 12(1)-12(M) based on a second number of target voltages 14(1)-14(K), and output the first number of ET modulation voltages 12(1)-12(M) via a third number of voltage outputs 16(1)-16(N). As will be described later in Figure 3-6 As discussed in , the ET circuit 10 may be used in an ET power amplifier system to flexibly enable ET power management based on any number of transceiver circuits and for any number of power amplifier circuits.

[0026] The ET circuit 10 includes an ET voltage circuit 18. The ET voltage circuit 18 includes a first number of tracker circuits 20(1)-20(M) and a second number of voltage inputs 22(1)-22(K). The second number of voltage inputs 22(1)-22(K) are configured to receive a second number of target voltages 14(1)-14(K), respectively. The first number of tracker circuits 20(1)-20(M) are configured to generate a first number of ET modulation voltages 12(1)-12(M) based on the second number of target voltages 14(1)-14(K).

[0027] The ET circuit 10 includes a control circuit 24, which may be, for example, a microprocessor, a microcontroller, or a field programmable gate array (FPGA). The ET circuit 10 may be configured to control the ET voltage circuit 18 via a control signal 26. Notably, the first number of tracker circuits 20(1)-20(M) may not be equal to the second number of voltage inputs 22(1)-22(K). In this regard, the control circuit 24 may be configured to couple a selected number of the first number of tracker circuits 20(1)-20(M) to a selected number of the second number of voltage inputs 22(1)-22(K) to receive a selected number of target voltages 14(1)-14(K). Thus, the selected number of tracker circuits may generate a selected number of ET modulation voltages of the first number of ET modulation voltages 12(1)-12(M) based on the selected number of target voltages. The control circuit 24 is also configured to selectively provide the selected number of ET modulation voltages to a third number of voltage outputs 16(1)-16(M).

[0028] ET voltage circuit 18 may include input switch circuit 28 coupled between a first number of tracker circuits 20(1)-20(M) and a second number of voltage inputs 22(1)-22(K). In this regard, control circuit 24 may control input switch circuit 28 to couple a selected number of tracker circuits to a selected number of voltage inputs. Input switch circuit 28 may be implemented based on any suitable number and type of switches.

[0029] The ET voltage circuit 18 may include an output switching circuit 30 coupled between a first number of tracker circuits 20(1)-20(M) and a third number of voltage outputs 16(1)-16(N). In this regard, the control circuit 24 may control the output switching circuit 30 to couple a selected number of tracker circuits to the third number of voltage outputs 16(1)-16(N). The output switching circuit 30 may be implemented based on any suitable number and type of switches.

[0030] In one non-limiting example, the second number of voltage inputs 22(1)-22(K) is greater than the first number of tracker circuits 20(1)-20(M) (K>M). In this regard, the control circuit 24 may control the input switching circuit 28 to couple the first number of tracker circuits 20(1)-20(M) to a selected subset of the second number of voltage inputs 22(1)-22(K) (e.g., M out of K voltage inputs) to receive a selected subset of the target voltages 14(1)-14(K) (e.g., M out of K target voltages). Accordingly, the first number of tracker circuits 20(1)-20(M) may generate a first number of ET modulation voltages based on the selected subset of the target voltages 14(1)-14(K).

[0031] In another non-limiting example, the second number of voltage inputs 22(1)-22(K) is less than the first number of tracker circuits 20(1)-20(M) (K<M). In this regard, the control circuit 24 may activate a selected subset of the first number of tracker circuits 20(1)-20(M) (e.g., K out of M tracker circuits). The control circuit 24 also controls the input switching circuit 28 to couple the selected subset of the first number of tracker circuits 20(1)-20(M) to the second number of voltage inputs 22(1)-22(K) to receive the second number of target voltages 14(1)-14(K). Accordingly, the selected subset of the first number of tracker circuits 20(1)-20(M) generates a selected subset of the first number of ET modulation voltages 12(1)-12(M) (e.g., K out of M ET modulation voltages).

[0032] In another non-limiting example, the first number of tracker circuits 20(1)-20(M) is equal to the second number of voltage inputs 22(1)-22(K) (K = M). In this regard, the control circuit 24 may control the input switching circuit 28 to couple the first number of tracker circuits 20(1)-20(M) to the second number of voltage inputs 22(1)-22(K) to receive the second number of target voltages 14(1)-14(K). Accordingly, the first number of tracker circuits 20(1)-20(M) generates a first number of ET modulation voltages 12(1)-12(M) based on the second number of target voltages 14(1)-14(K).

[0033] In another non - limiting example, the first quantity of tracker circuits 20(1)-20(M) is equal to the third quantity of voltage outputs 16(1)-16(N) (M = N). In this regard, the control circuit 24 controls the output switch circuit 30 to couple the first quantity of tracker circuits 20(1)-20(M) to the third quantity of voltage outputs 16(1)-16(N) to output the first quantity of ET modulated voltages 12(1)-12(M).

[0034] It should be noted that the third quantity of voltage outputs 16(1)-16(N) can be more than the first quantity of tracker circuits 20(1)-20(M) (N > M). In this regard, Figure 2 is a schematic diagram of an exemplary illustration of the output switch circuit 30 that is configured to output a smaller quantity of ET modulated voltages to a larger quantity of voltage outputs. Figure 1 Common elements between Figure 1 and Figure 2 are shown with common element numbers and are not described again here.

[0035] As Figure 2 shown, the third quantity of voltage outputs 16(1)-16(N) includes a plurality of main voltage outputs 16(1)-16(X) (X < N) and a plurality of auxiliary voltage outputs 16(X + 1)-16(N). In this regard, the control circuit 24 can control the output switch circuit 30 to couple one or more of the first quantity of tracker circuits 20(1)-20(M) to one or more selected main voltage outputs among the main voltage outputs 16(1)-16(X). The control circuit 24 can also control the output switch circuit 30 to couple one or more of the first quantity of tracker circuits 20(1)-20(M) to one or more selected auxiliary voltage outputs among the auxiliary voltage outputs 16(X + 1)-16(M).

[0036] Figure 1 The ET circuit 10 of Figure 3 can be used in an ET power amplifier system to flexibly enable ET power management based on any quantity of transceiver circuits and for any quantity of power amplifier circuits. In this regard, Figure 1 is a schematic diagram of an exemplary power amplifier system 32 according to an embodiment of the present disclosure, the power amplifier system 32 being configured to include Figure 1 and Figure 3 Common elements between are shown with common element numbers and are not described again here.

[0037] The power amplifier system 32 includes a plurality of amplifier circuits 34 coupled to the third number of voltage outputs 16(1)-16(N). Each amplifier circuit 34 is configured to amplify a radio frequency (RF) signal 36 based on an ET modulation voltage among the ET modulation voltages 12(1)-12(M). Figure 3 Only one amplifier circuit is shown coupled to each of the third number of voltage outputs 16(1)-16(N), but it should be understood that more than one amplifier circuit 34 may be coupled to each of the third number of voltage outputs 16(1)-16(N). It should also be understood that the amplifier circuits 34 may be configured to receive the same or different ones of the ET modulation voltages 12(1)-12(M). It should further be understood that the amplifier circuits 34 may amplify the same or different RF signals individually or simultaneously.

[0038] The power amplifier system 32 includes a transceiver circuit 38. The transceiver circuit 38 is configured to provide a second number of target voltages 14(1)-14(K) to a second number of voltage inputs 22(1)-22(K).

[0039] The power amplifier system 32 may be modified to include more than one transceiver circuit, as described below. Figure 4 In this regard, Figure 4 is a schematic diagram of an exemplary power amplifier system 40 according to another embodiment of the present disclosure, the power amplifier system 40 being configured to include Figure 1 ET circuit 10. Figure 3 and Figure 4 Common elements between the embodiments are shown with common element numbers and will not be described again here.

[0040] The power amplifier system 40 includes a transceiver system 42, which includes a plurality of transceiver circuits 44(1)-44(L). The transceiver circuits 44(1)-44(L) may be configured to support a variety of wireless communication technologies, including but not limited to Long Term Evolution (LTE), fifth generation new radio (5G-NR), and Wi-Fi. The transceiver circuits 44(1)-44(L) may be configured to collectively provide a second number of target voltages 14(1)-14(K) to a second number of voltage inputs 22(1)-22(K).

[0041] Figure 3 The power amplifier system 32 may be modified to include more than one ET circuit 10. In this regard, Figure 5 is a schematic diagram of an exemplary power amplifier system 46 according to one embodiment of the present disclosure, the power amplifier system 46 being configured to include at least two Figure 1 ET circuit 10. Figure 3 and Figure 5 Common elements between the embodiments are shown with common element numbers and will not be described again here.

[0042] The power amplifier system 46 includes at least one second ET circuit 10A, which is functionally equivalent to Figure 1 ET circuit 10. Similar to ET circuit 10, second ET circuit 10A is coupled to transceiver circuit 38 to receive a second number of target voltages 14(1)-14(K). Thus, second ET circuit 10A outputs a first number of ET modulation voltages 12(1)-12(M) via a third number of voltage outputs 16(1)-16(N). Power amplifier system 46 may include a plurality of second amplifier circuits 34A coupled to second ET circuit 10A. Second amplifier circuits 34A are configured to amplify a plurality of RF signals 36A based on the first number of ET modulation voltages 12(1)-12(M).

[0043] Figure 4 The power amplifier system 40 may also be modified to include more than one ET circuit 10. In this regard, Figure 6 is a schematic diagram of an exemplary power amplifier system 48 according to another embodiment of the present disclosure, the power amplifier system 48 being configured to include at least two Figure 1 ET circuit 10. Figure 3 , Figure 5 and Figure 6 Common elements between the embodiments are shown with common element numbers and will not be described again here.

[0044] Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered to be within the scope of the concepts disclosed herein and the appended claims.

Claims

1. An envelope tracking (ET) circuit, comprising: ET voltage circuit, the ET voltage circuit comprising: a first number of tracker circuits configured to generate a first number of ET modulation voltages; a second number of voltage inputs configured to receive a second number of target voltages, wherein the second number of voltage inputs is not equal to the first number of the tracker circuit; and a third number of voltage outputs configured to output the first number of ET modulated voltages; and A control circuit, the control circuit being configured to: coupling a selected number of the first number of tracker circuits to a selected number of the second number of voltage inputs, wherein the selected number of tracker circuits are configured to: receiving, via the selected number of voltage inputs, a selected number of target voltages from the second number of target voltages; and generating a selected number of ET modulation voltages among the first number of ET modulation voltages based on the selected number of target voltages; and The selected number of ET modulation voltages is selectively provided to the third number of voltage outputs.

2. The envelope tracking (ET) circuit of claim 1, wherein: The ET voltage circuit further includes an input switch circuit coupled between the first number of tracker circuits and the second number of voltage inputs; as well as The control circuit is also configured to control the input switch circuit to couple the selected number of tracker circuits to the selected number of voltage inputs.

3. The envelope tracking (ET) circuit of claim 1, wherein: The ET voltage circuit further includes an output switch circuit coupled between the first number of tracker circuits and the third number of voltage outputs; as well as The control circuit is further configured to control the output switch circuit to selectively provide the selected number of ET modulation voltages to the third number of voltage outputs.

4. The envelope tracking (ET) circuit of claim 1 , wherein the control circuit is further configured to couple the first number of tracker circuits to a selected subset of the second number of voltage inputs in response to the first number of tracker circuits being less than the second number of voltage inputs.

5. The envelope tracking (ET) circuit of claim 1 , wherein the control circuit is further configured to activate and couple a selected subset of the first number of tracker circuits to the second number of voltage inputs in response to the first number of tracker circuits being greater than the second number of voltage inputs.

6. The envelope tracking (ET) circuit of claim 1 , wherein the control circuit is further configured to couple the first number of tracker circuits to the third number of voltage outputs, respectively, in response to the first number of tracker circuits being equal to the third number of voltage outputs.

7. The envelope tracking (ET) circuit of claim 1, wherein: The third number of voltage outputs includes a plurality of primary voltage outputs and a plurality of auxiliary voltage outputs; and The control circuit is further configured to: coupling one or more of the first number of tracker circuits to one or more selected ones of the plurality of primary voltage outputs; as well as One or more of the first number of tracker circuits are coupled to one or more selected ones of the plurality of auxiliary voltage outputs.

8. The envelope tracking (ET) circuit of claim 1, wherein: The ET voltage circuit further comprises: an input switching circuit coupled between the first number of tracker circuits and the second number of voltage inputs; and an output switching circuit coupled between the first number of tracker circuits and the third number of voltage outputs; and The control circuit is further configured to: controlling the input switch circuit to couple the selected number of tracker circuits to the selected number of voltage inputs; and The output switch circuit is controlled to selectively provide the selected number of ET modulation voltages to the third number of voltage outputs.

9. An envelope tracking (ET) circuit as described in claim 8, wherein the control circuit is also configured to control the input switch circuit to couple the first number of tracker circuits to a selected subset of the second number of voltage inputs in response to the first number of tracker circuits being less than the second number of voltage inputs.

10. An envelope tracking (ET) circuit as described in claim 8, wherein the control circuit is further configured to activate a selected subset of the first number of tracker circuits and control the input switch circuit to couple the selected subset of the first number of tracker circuits to the second number of voltage inputs in response to the first number of tracker circuits being greater than the second number of voltage inputs.

11. The envelope tracking (ET) circuit of claim 8, wherein the control circuit is further configured to control the output switch circuit to couple the first number of tracker circuits to the third number of voltage outputs, respectively, in response to the first number of tracker circuits being equal to the third number of voltage outputs.

12. The envelope tracking (ET) circuit of claim 8, wherein: The third number of voltage outputs includes a plurality of primary voltage outputs and a plurality of auxiliary voltage outputs; and The control circuit is further configured to: controlling the output switch circuit to couple one or more of the first number of tracker circuits to one or more selected primary voltage outputs of the plurality of primary voltage outputs; as well as The output switch circuit is controlled to couple one or more of the first number of tracker circuits to one or more selected auxiliary voltage outputs of the plurality of auxiliary voltage outputs.

13. A power amplifier system, comprising: An envelope tracking ET circuit, the ET circuit comprising: ET voltage circuit, the ET voltage circuit comprising: a first number of tracker circuits configured to generate a first number of ET modulation voltages; a second number of voltage inputs configured to receive a second number of target voltages, wherein the second number of voltage inputs is not equal to the first number of the tracker circuit; and a third number of voltage outputs configured to output the first number of ET modulated voltages; and A control circuit, the control circuit being configured to: coupling a selected number of the first number of tracker circuits to a selected number of the second number of voltage inputs, wherein the selected number of tracker circuits are configured to: receiving, via the selected number of voltage inputs, a selected number of target voltages from the second number of target voltages; and generating a selected number of ET modulation voltages among the first number of ET modulation voltages based on the selected number of target voltages; and selectively providing the selected number of ET modulation voltages to the third number of voltage outputs; and A plurality of power amplifier circuits are coupled to the third number of voltage outputs, each power amplifier circuit being configured to amplify a radio frequency (RF) signal based on an ET modulation voltage of the first number of ET modulation voltages.

14. The power amplifier system of claim 13, wherein each of the third number of voltage outputs is coupled to one or more of the plurality of power amplifier circuits.

15. The power amplifier system of claim 13, wherein: The ET voltage circuit further includes an input switch circuit coupled between the first number of tracker circuits and the second number of voltage inputs; as well as The control circuit is also configured to control the input switch circuit to couple the selected number of tracker circuits to the selected number of voltage inputs.

16. The power amplifier system of claim 13, wherein: The ET voltage circuit further includes an output switch circuit coupled between the first number of tracker circuits and the third number of voltage outputs; as well as The control circuit is further configured to control the output switch circuit to selectively provide the selected number of ET modulation voltages to the third number of voltage outputs.

17. The power amplifier system of claim 13, wherein the control circuit is further configured to couple the first number of tracker circuits to a selected subset of the second number of voltage inputs in response to the first number of tracker circuits being less than the second number of voltage inputs.

18. The power amplifier system of claim 13, wherein the control circuit is further configured to activate and couple a selected subset of the first number of tracker circuits to the second number of voltage inputs in response to the first number of tracker circuits being greater than the second number of voltage inputs.

19. The power amplifier system of claim 13, wherein the control circuit is further configured to couple the first number of tracker circuits to the third number of voltage outputs, respectively, in response to the first number of tracker circuits being equal to the third number of voltage outputs.

20. The power amplifier system of claim 13, wherein: The third number of voltage outputs includes a plurality of primary voltage outputs and a plurality of auxiliary voltage outputs; and The control circuit is further configured to: coupling one or more of the first number of tracker circuits to one or more selected ones of the plurality of primary voltage outputs; as well as One or more of the first number of tracker circuits are coupled to one or more selected ones of the plurality of auxiliary voltage outputs.

21. The power amplifier system of claim 13, further comprising a transceiver circuit configured to provide the second number of target voltages to the second number of voltage inputs.

22. The power amplifier system of claim 21 further comprising a second ET circuit coupled to the transceiver circuit and configured to receive the second number of target voltages and output the first number of ET modulation voltages via the third number of voltage outputs.

23. The power amplifier system of claim 22, further comprising a plurality of second amplifier circuits coupled to the second ET circuit.

24. The power amplifier system of claim 13, further comprising a transceiver system comprising a plurality of transceiver circuits configured to collectively provide the second number of target voltages to the second number of voltage inputs.

25. The power amplifier system of claim 24, further comprising a second ET circuit coupled to the transceiver system and configured to receive the second number of target voltages and output the first number of ET modulation voltages via the third number of voltage outputs.

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