ENVELOPE TRACKING POWER MANAGEMENT CIRCUIT

Abstract

An envelope tracking power management circuit is disclosed. An envelope tracking power management circuit includes a first envelope tracking amplifier(s) and a second envelope tracking amplifier(s), each configured to amplify a respective radio frequency (RF) signal(s) based on a respective supply voltage. A power management circuit can determine that a selected envelope tracking amplifier, which can be either the first envelope tracking amplifier(s) or the second envelope tracking amplifier(s), receives the respective supply voltage lower than a voltage required to amplify the respective RF signal(s) to a predetermined voltage. In response, the power management circuit provides a boosted voltage, which is no less than the required voltage, to the selected envelope tracking amplifier. As such, it is possible to enable the selected envelope tracking amplifier to amplify the respective RF signal(s) to the predetermined voltage without increasing cost, footprint, and power consumption of the envelope tracking power management circuit.

Claims

1. An envelope tracking power management circuit, comprising: at least one first envelope tracking amplifier configured to amplify at least one first radio frequency (RF) signal based on a first supply voltage received on a first supply voltage input for transmission from at least one first RF transmission circuit in at least one first RF carrier; at least one second envelope tracking amplifier configured to amplify at least one second RF signal based on a second supply voltage received on a second supply voltage input for transmission from at least one second RF transmission circuit in at least one second RF carrier; and a power management circuit configured to: determine a selected envelope tracking amplifier among the at least one first envelope tracking amplifier and the at least one second envelope tracking amplifier, wherein the selected envelope tracking amplifier receives a respective supply voltage lower than a voltage required to amplify a respective RF signal to a predetermined voltage; and provide a boosted voltage to a respective supply voltage input of the selected envelope tracking amplifier, wherein the boosted voltage is greater than or equal to the voltage required to amplify the respective RF signal to the predetermined voltage.

2. The envelope tracking power management circuit of claim 1, wherein the power management circuit is configured to: determine that the at least one first envelope tracking amplifier receives the first supply voltage lower than the voltage required to amplify the at least one first RF signal to the predetermined voltage; and provide the boosted voltage to the first supply voltage input of the at least one first envelope tracking amplifier to amplify the at least one first RF signal to the predetermined voltage.

3. The envelope tracking power management circuit of claim 1, wherein the power management circuit is configured to: determine that the at least one second envelope tracking amplifier receives the second supply voltage lower than the voltage required to amplify the at least one second RF signal to the predetermined voltage; and provide the boosted voltage to the second supply voltage input of the at least one second envelope tracking amplifier to amplify the at least one second RF signal to the predetermined voltage.

4. The envelope tracking power management circuit of claim 1, wherein the power management circuit comprises: first voltage boost circuitry configured to: generate a first boosted voltage higher than the first supply voltage; and provide the first boosted voltage to a first boosted voltage output; and second voltage boost circuitry configured to: generate a second boosted voltage higher than the second supply voltage; and provide the second boosted voltage to a second boosted voltage output.

5. The envelope tracking power management circuit of claim 4, wherein: the first boosted voltage is less than or equal to two times the first supply voltage; and the second boosted voltage is less than or equal to two times the second supply voltage.

6. The envelope tracking power management circuit of claim 4, wherein the power management circuit further comprises: first buck circuitry configured to generate a first electrical current based on a first input voltage and provide the first electrical current to the at least one first RF transmission circuit; and second buck circuitry configured to generate a second electrical current based on a second input voltage and provide the second electrical current to the at least one second RF transmission circuit.

7. The envelope tracking power management circuit of claim 6, wherein the power management circuit further comprises: first switcher circuitry coupled to the first voltage boost circuitry and the first buck circuitry; and second switcher circuitry coupled to the second voltage boost circuitry and the second buck circuitry.

8. The envelope tracking power management circuit of claim 7, wherein the power management circuit further comprises at least one control circuit communicatively coupled to the first switcher circuitry and the second switcher circuitry.

9. The envelope tracking power management circuit of claim 8, wherein the at least one control circuit is configured to: determine that the at least one first envelope tracking amplifier receives the first supply voltage lower than the voltage required to amplify the at least one first RF signal to the predetermined voltage; and couple the second boosted voltage output of the second voltage boost circuitry to the first supply voltage input of the at least one first envelope tracking amplifier to provide the second boosted voltage to the at least one first envelope tracking amplifier.

10. The envelope tracking power management circuit of claim 9, wherein the power management circuit further comprises first low drop-off output (LDO) circuitry configured to provide the first supply voltage and the second boosted voltage to the first supply voltage input.

11. The envelope tracking power management circuit of claim 9, wherein the power management circuit further comprises: low drop-off output (LDO) circuitry configured to provide the first supply voltage to the first supply voltage input; and boosted LDO circuitry configured to provide the second boosted voltage to the first supply voltage input.

12. The envelope tracking power management circuit of claim 9, wherein the power management circuit further comprises a p-type metal-oxide semiconductor field-effect transistor (pMOSFET) configured to regulate the second boosted voltage.

13. The envelope tracking power management circuit of claim 9, wherein the at least one control circuit is further configured to: control the first switcher circuitry to provide the first supply voltage to the first buck circuitry as the first input voltage; and control the second switcher circuitry to provide the second supply voltage to the second buck circuitry as the second input voltage.

14. The envelope tracking power management circuit of claim 8, wherein the at least one control circuit is configured to: determine that the at least one second envelope tracking amplifier receives the second supply voltage lower than the voltage required to amplify the at least one second RF signal to the predetermined voltage; and couple the first boosted voltage output of the first voltage boost circuitry to the second supply voltage input of the at least one second envelope tracking amplifier to provide the first boosted voltage to the at least one second envelope tracking amplifier.

15. The envelope tracking power management circuit of claim 14, wherein the power management circuit further comprises second low drop-off output (LDO) circuitry configured to provide the second supply voltage and the first boosted voltage to the second supply voltage input.

16. The envelope tracking power management circuit of claim 14, wherein the power management circuit further comprises: low drop-off output (LDO) circuitry configured to provide the second supply voltage to the second supply voltage input; and boosted LDO circuitry configured to provide the first boosted voltage to the second supply voltage input.

17. The envelope tracking power management circuit of claim 14, wherein the power management circuit further comprises a p-type metal-oxide semiconductor field-effect transistor (pMOSFET) configured to regulate the first boosted voltage.

18. The envelope tracking power management circuit of claim 14, wherein the at least one control circuit is further configured to: control the first switcher circuitry to provide the first supply voltage to the first buck circuitry as the first input voltage t; and control the second switcher circuitry to provide the second supply voltage to the second buck circuitry as the second input voltage.

19. The envelope tracking power management circuit of claim 1, wherein: the at least one first RF signal comprises a first low-band RF signal and a first mid-band RF signal; the at least one first RF transmission circuit comprises a first low-band transmission circuit and a first mid-band transmission circuit configured to transmit the first low-band RF signal and the first mid-band RF signal, respectively; the at least one second RF signal comprises a second mid-band RF signal and a second high-band RF signal; and the at least one second RF transmission circuit comprises a second mid-band transmission circuit and a second high-band transmission circuit configured to transmit the second mid-band RF signal and the second high-band RF signal, respectively.

20. An envelope tracking power management circuit, comprising: at least one first envelope tracking amplifier configured to amplify at least one first radio frequency (RF) signal based on a first supply voltage received on a first supply voltage input for transmission from at least one first RF transmission circuit in at least one first RF carrier; at least one second envelope tracking amplifier configured to amplify at least one second RF signal based on a second supply voltage received on a second supply voltage input for transmission from at least one second RF transmission circuit in at least one second RF carrier; and a power management circuit configured to: determine that the at least one first envelope tracking amplifier receives the first supply voltage lower than a voltage required to amplify the at least one first RF signal to a predetermined voltage; and provide a boosted voltage to the first supply voltage input of the at least one first envelope tracking amplifier, wherein the boosted voltage is greater than or equal to the voltage required to amplify the at least one first RF signal to the predetermined voltage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings incorporated in and forming a part of this specification illustrate several aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0011] FIG. 1 is a schematic diagram of an exemplary conventional envelope tracking power management circuit in which a first envelope tracking amplifier and a second envelope tracking amplifier are configured to amplify a first radio frequency (RF) signal and a second RF signal, respectively;

[0012] FIG. 2 is a schematic diagram of an exemplary envelope tracking power management circuit in which a selected envelope tracking amplifier among at least one first envelope tracking amplifier and at least one second envelope tracking amplifier can be configured to receive a boosted voltage without requiring dedicated voltage boost circuitry;

[0013] FIG. 3 is a schematic diagram of an exemplary voltage distribution circuit that can be provided in the envelope tracking power management circuit of FIG. 2;

[0014] FIG. 4 is a schematic diagram of an exemplary simplified voltage distribution circuit that can be provided in the envelope tracking power management circuit of FIG. 2;

[0015] FIG. 5 is a schematic diagram of an exemplary low drop-off output (LDO) circuit including LDO circuitry configured to receive a supply voltage and boosted LDO circuitry configured to receive a boosted voltage higher than the supply voltage; and

[0016] FIG. 6 is a schematic diagram of an exemplary voltage regulating circuit configured to regulate a first boosted voltage and a second boosted voltage of FIG. 2.

DETAILED DESCRIPTION

[0017] The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the disclosure and illustrate the best mode of practicing the disclosure. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

[0018] Aspects disclosed in the detailed description include an envelope tracking power management circuit. An envelope tracking power management circuit includes a first envelope tracking amplifier(s) and a second envelope tracking amplifier(s), each configured to amplify a respective radio frequency (RF) signal(s) based on a respective supply voltage. A power management circuit can determine that a selected envelope tracking amplifier, which can be either the first envelope tracking amplifier(s) or the second envelope tracking amplifier(s), receives the respective supply voltage lower than a voltage required to amplify the respective RF signal(s) to a predetermined voltage. In response, the power management circuit provides a boosted voltage, which is no less than the required voltage, to the selected envelope tracking amplifier. As such, it is possible to enable the selected envelope tracking amplifier to amplify the respective RF signal(s) to the predetermined voltage without increasing cost, footprint, and power consumption of the envelope tracking power management circuit.

[0019] Before discussing the envelope tracking power management circuit of the present disclosure, a brief discussion of a conventional envelope tracking power management circuit is first provided with reference to FIG. 1. The discussion of specific exemplary aspects of an envelope tracking power management circuit starts below with reference to FIG. 2.

[0020] In this regard, FIG. 1 is a schematic diagram of an exemplary conventional envelope tracking power management circuit 10 in which a first envelope tracking amplifier 12 and a second envelope tracking amplifier 14 are configured to amplify a first RF signal 16 and a second RF signal 18, respectively. The first envelope tracking amplifier 12 and the second envelope tracking amplifier 14 are configured to receive a first supply voltage V.sub.BAT1 on a first supply voltage input 20 and a second supply voltage V.sub.BAT2 on a second supply voltage input 22, respectively. In this regard, the first envelope tracking amplifier 12 amplifies the first RF signal 16 to a first voltage V.sub.1 based on the first supply voltage V.sub.BAT1. Similarly, the second envelope tracking amplifier 14 amplifies the second RF signal 18 to a second voltage V.sub.2 based on the second supply voltage V.sub.BAT2.

[0021] The first envelope tracking amplifier 12 may be controlled by a first envelope tracking controller 24 to amplify the first RF signal 16 based on a first envelope tracking feedback signal 26. Likewise, the second envelope tracking amplifier 14 can be controlled by a second envelope tracking controller 28 to amplify the second RF signal 18 based on a second envelope tracking feedback signal 30.

[0022] The conventional envelope tracking power management circuit 10 also includes first voltage boost circuitry 32, second voltage boost circuitry 34, first buck circuitry 36, and second buck circuitry 38. The first voltage boost circuitry 32 (also known as a first charge pump) is configured to generate a first boosted voltage V.sub.BOOST1 based on the first supply voltage V.sub.BAT1. In a non-limiting example, the first voltage boost circuitry 32 can generate the first boosted voltage V.sub.BOOST1 that is less than or equal to two times the first supply voltage V.sub.BAT1 (V.sub.BOOST1≦2*V.sub.BAT1). The second voltage boost circuitry 34 (also known as a second charge pump) is configured to generate a second boosted voltage V.sub.BOOST2 based on the second supply voltage V.sub.BAT2. In a non-limiting example, the second voltage boost circuitry 34 can generate the second boosted voltage V.sub.BOOST2 that is less than or equal to two times the second supply voltage V.sub.BAT2 (V.sub.BOOST2≦2*V.sub.BAT2).

[0023] The conventional envelope tracking power management circuit 10 also includes first switcher circuitry 40 and second switcher circuitry 42. The first switcher circuitry 40 is coupled to the first voltage boost circuitry 32 and the first buck circuitry 36. The first switcher circuitry 40 can be controlled (e.g., by a control circuit) to provide either the first supply voltage V.sub.BAT1 or the first boosted voltage V.sub.BOOST1 to the first buck circuitry 36 as a first input voltage V.sub.IN1. The first buck circuitry 36 is configured to generate a first electrical current I.sub.1 based on the first input voltage V.sub.IN1 and respective resistance of a first inductor 44. The first buck circuitry 36 is also configured to provide the first electrical current I.sub.1 to at least one first RF transmission circuit 46 for transmission in at least one first RF carrier (e.g., channel, band, etc.). Accordingly, the first RF signal 16 received by the first RF transmission circuit 46 has a first power P.sub.1 that is a function of the first electrical current I.sub.1 and the first voltage V.sub.1 (P.sub.1=I.sub.1*V.sub.1). The first RF transmission circuit 46 may include first power amplifiers 48. The first RF transmission circuit 46 is configured to distribute the first RF signal 16 in the first RF carrier at a first transmit power P.sub.TX1 (P.sub.TX1≦P.sub.1).

[0024] The second switcher circuitry 42 is coupled to the second voltage boost circuitry 34 and the second buck circuitry 38. The second switcher circuitry 42 can be controlled (e.g., by a control circuit) to provide either the second supply voltage V.sub.BAT2 or the second boosted voltage V.sub.BOOST2 to the second buck circuitry 38 as a second input voltage V.sub.IN2. The second buck circuitry 38 is configured to generate a second electrical current I.sub.2 based on the second input voltage V.sub.IN2 and respective resistance of a second inductor 50. The second buck circuitry 38 is also configured to provide the second electrical current I.sub.2 to at least one second RF transmission circuit 52 for transmission in at least one second RF carrier (e.g., channel, band, etc.). Accordingly, the second RF signal 18 received by the second RF transmission circuit 52 has a second power P.sub.2 that is a function of the second electrical current I.sub.2 and the second voltage V.sub.2 (P.sub.2=I.sub.2*V.sub.2). The second RF transmission circuit 52 may include second power amplifiers 54. The second RF transmission circuit 52 is configured to distribute the second RF signal 18 in the second RF carrier at a second transmit power P.sub.TX2 (P.sub.TX2≦P.sub.2).

[0025] The first RF carrier and the second RF carrier may be located in licensed RF spectrums. As such, a sum of the first transmit power P.sub.TX1 and the second transmit power P.sub.TX2 may be subject to an average power limit set by standard organizations and/or regulatory authorities. For example, if the first RF signal 16 and the second RF signal 18 are transmitted in a long-term evolution (LTE) system, the sum of the first transmit power P.sub.TX1 and the second transmit power P.sub.TX2 will be subject to an average power limit of 23 decibel-milliwatts (dBm).

[0026] However, under certain usage scenarios and/or operational conditions, it may be necessary to transmit one of the first RF signal 16 and the second RF signal 18 at an increased power to help improve signal-to-noise ratio (SNR) at a respective wireless receiver. For example, it can be necessary to transmit the first RF signal 16 at a peak power of 27.3 dBm in response to a need for improving the SNR. In this case, if load-lines of the first power amplifiers 48 in the first RF transmission circuit 46 are so configured to require the first voltage V.sub.1 to be at 4.2 volts (V) for example, then the first supply voltage V.sub.BAT1 of the first envelope tracking amplifier 12 would need to be approximately 4.5 V according to the equation (Eq. 1) below.

V.sub.BAT1=V.sub.1+P.sub.headroom (Eq. 1)

[0027] In the equation above, P.sub.headroom is a voltage corresponding to a peak of the first electrical current I.sub.1 generated by the first buck circuitry 36, which can be approximately 0.3 V, for example. However, the conventional envelope tracking power management circuit 10 may be configured to limit the first supply voltage V.sub.BAT1 to 3.4 V, which is the minimum supply voltage without power derating being applied. In this regard, the first envelope tracking amplifier 12 will need the first supply voltage V.sub.BAT1 to be boosted from 3.4 V to 4.5 V to be able to generate the first voltage V.sub.1 at 4.2 V. One possible solution is to add a dedicated voltage boost circuitry in the conventional envelope tracking power management circuit to boost the first supply voltage V.sub.BAT1 from 3.4 V to 4.5 V. However, adding the dedicated voltage boost circuitry in the conventional envelope tracking power management circuit 10 can lead to increased cost, footprint, and power consumption. As such, it may be desired to boost the first supply voltage V.sub.BAT1 without adding additional hardware in the conventional envelope tracking power management circuit 10.

[0028] As discussed above, the second voltage boost circuitry 34 can generate the second boosted voltage V.sub.BOOST2≦2*V.sub.BAT2, and the second buck circuitry 38 can generate the second electrical current I.sub.2 based on either the second input voltage V.sub.IN2 or the second boosted voltage V.sub.BOOST2. Given that the sum of the first transmit power P.sub.TX1 and the second transmit power P.sub.TX2 are subject to the average power limit (e.g., 23 dBm in the LTE system), the second RF signal 18 would need to be transmitted at a reduced second transmit power P.sub.TX2 when the first RF signal 16 is transmitted at an increased first transmit power P.sub.TX1. As such, the second buck circuitry 38 can be configured to generate the second electrical current I.sub.2 based on the second input voltage V.sub.IN2.

[0029] In this regard, as further discussed in the exemplary aspects below, it is possible to configure the second switcher circuitry 42 to provide the second boosted voltage V.sub.BOOST2 from the second voltage boost circuitry 34 to the first envelope tracking amplifier 12, thus allowing the first envelope tracking amplifier 12 to generate the first voltage V.sub.1 that is required to produce the increased first transmit power P.sub.TX1 for the first RF signal 16. Likewise, it is also possible to configure the first switcher circuitry 40 to provide the first boosted voltage V.sub.BOOST1 from the first voltage boost circuitry 32 to the second envelope tracking amplifier 14 when the second RF signal 18 needs to be transmitted at an increased second transmit power P.sub.TX2. By utilizing the first voltage boost circuitry 32 or the second voltage boost circuitry 34, which already exist in the conventional envelope tracking power management circuit 10, to provide the boosted voltage to the second envelope tracking amplifier 14 or the first envelope tracking amplifier 12, it is possible to eliminate the need for dedicated power boost circuitries, thus helping to reduce cost, footprint, and power consumption in an envelope tracking power management circuit.

[0030] In this regard, FIG. 2 is a schematic diagram of an exemplary envelope tracking power management circuit 56 in which a selected envelope tracking amplifier among at least one first envelope tracking amplifier 58 and at least one second envelope tracking amplifier 60 can be configured to receive a boosted voltage without requiring dedicated voltage boost circuitry. The first envelope tracking amplifier 58 is configured to amplify at least one first RF signal 62 based on a first supply voltage V.sub.BAT1 received on a first supply voltage input 64 for transmission from at least one first RF transmission circuit 66 in at least one first RF carrier. The second envelope tracking amplifier 60 is configured to amplify at least one second RF signal 68 based on a second supply voltage V.sub.BAT2 received on a second supply voltage input 70 for transmission from at least one second RF transmission circuit 72 in at least one second RF carrier.

[0031] The envelope tracking power management circuit 56 includes a power management circuit 74. The power management circuit 74 includes first voltage boost circuitry 76 (also known as a first charge pump) configured to generate a first boosted voltage V.sub.BOOST1 and second voltage boost circuitry 78 (also known as a second charge pump) configured to generate a second boosted voltage V.sub.BOOST2. The power management circuit 74 includes at least one control circuit 80, which can be a microprocessor, a microcontroller, a digital signal processor (DSP), and a field programmable gate array (FPGA), for example. The control circuit 80 is configured to determine that the selected envelope tracking amplifier receives a respective supply voltage that is lower than a voltage required to amplify a respective RF signal to a predetermined voltage. In response, the control circuit 80 provides a boosted voltage among the first boosted voltage V.sub.BOOST1 and the second boosted voltage V.sub.BOOST2 to a respective supply voltage input of the selected envelope tracking amplifier. The boosted voltage is configured to be greater than or equal to the voltage required to amplify the respective RF signal to the predetermined voltage.

[0032] In one non-limiting example, the control circuit 80 may determine that the first supply voltage V.sub.BAT1 received by the first envelope tracking amplifier 58 is lower than the voltage required to amplify the first RF signal 62 to the predetermined voltage. As such, the control circuit 80 is configured to provide the second boosted voltage V.sub.BOOST2 to the first supply voltage input 64 of the first envelope tracking amplifier 58 to amplify the first RF signal 62 to the predetermined voltage. In another non-limiting example, the control circuit 80 may determine that the second supply voltage V.sub.BAT2 received by the second envelope tracking amplifier 60 is lower than the voltage required to amplify the second RF signal 68 to the predetermined voltage. As such, the control circuit 80 is configured to provide the first boosted voltage V.sub.BOOST1 to the second supply voltage input 70 of the second envelope tracking amplifier 60 to amplify the second RF signal 68 to the predetermined voltage.

[0033] As further discussed below, both the first voltage boost circuitry 76 and the second voltage boost circuitry 78 are provided in the power management circuit 74 to provide predefined functionalities, as opposed to being dedicated to providing the boosted voltage to the selected envelope tracking amplifier. In other words, the first voltage boost circuitry 76 and the second voltage boost circuitry 78 are existing elements in the power management circuit 74 that are reconfigured to provide the boosted voltage to the selected envelope tracking amplifier while continuing to provide the predefined functionalities. By reconfiguring the first voltage boost circuitry 76 or the second voltage boost circuitry 78 to provide the boosted voltage to the selected envelope tracking amplifier, it is possible to reduce cost, footprint, and power consumption in the envelope tracking power management circuit 56.

[0034] The first envelope tracking amplifier 58 is configured to amplify the first RF signal 62 to a first voltage V.sub.1 based on the first supply voltage V.sub.BAT1 received on the first supply voltage input 64. The second envelope tracking amplifier 60 is configured to amplify the second RF signal 68 to a second voltage V.sub.2 based on the second supply voltage V.sub.BAT2 received on the second supply voltage input 70. In a non-limiting example, the first supply voltage V.sub.BAT1 and the second supply voltage V.sub.BAT2 are received from a first direct current (DC) source 82 and a second DC source 84, respectively. In another non-limiting example, the first supply voltage V.sub.BAT1 and the second supply voltage V.sub.BAT2 both equal 3.4 V.

[0035] The first envelope tracking amplifier 58 is coupled to the first RF transmission circuit 66 via a first coupling point 85. The first envelope tracking amplifier 58 may be coupled to the first coupling point 85 via a first offset capacitor 86 configured to provide a first offset voltage V.sub.C1. The first offset voltage V.sub.C1, which can be 1 V for example, can help to raise the first voltage V.sub.1 to a modified first voltage V′.sub.1 (V′.sub.1=V.sub.1+V.sub.C1) at the first coupling point 85, thus helping to lower the first supply voltage V.sub.BAT1 required by the first envelope tracking amplifier 58 to improve power efficiency in the power management circuit 74. For example, if the first envelope tracking amplifier 58 is coupled directly to the first coupling point 85 without the first offset capacitor 86, then the modified first voltage V′.sub.1 will be the same as the first voltage V.sub.1. In this regard, if the modified first voltage V′.sub.1 at the first coupling point 85 is required to be 5 V for example, the first voltage V.sub.1 produced by the first envelope tracking amplifier 58 will also be 5 V. Accordingly, the first supply voltage V.sub.BAT1 needs to be at least 5 V. In contrast, if the first envelope tracking amplifier 58 is coupled to the first coupling point 85 via the first offset capacitor 86 that provides the 1 V first offset voltage V.sub.C1, then the first envelope tracking amplifier 58 would only need to produce the first voltage V.sub.1 at 4 V. As a result, the first supply voltage V.sub.BAT1 can be reduced to 4 V as well, thus helping to improve power efficiency in the power management circuit 74.

[0036] Similarly, the second envelope tracking amplifier 60 is coupled to the second RF transmission circuit 72 via a second coupling point 88. The second envelope tracking amplifier 60 may be coupled to the second coupling point 88 via a second offset capacitor 90 configured to provide a second offset voltage V.sub.C2. The second offset voltage V.sub.C2, which can be 1 V for example, can help to raise the second voltage V.sub.2 to a modified second voltage V′.sub.2 (V′.sub.2=V.sub.2+V.sub.C2) at the second coupling point 88.

[0037] The first voltage boost circuitry 76 is configured to generate the first boosted voltage V.sub.BOOST1 that is less than or equal to two times the first supply voltage V.sub.BAT1 (V.sub.BOOST1≦2*V.sub.BAT1). The first voltage boost circuitry 76 is configured to provide the first boosted voltage V.sub.BOOST1 to a first boosted voltage output 92. The second voltage boost circuitry 78 is configured to generate the second boosted voltage V.sub.BOOST2 that is less than or equal to two times the second supply voltage V.sub.BAT2 (V.sub.BOOST2≦2*V.sub.BAT2). The second voltage boost circuitry 78 is configured to provide the second boosted voltage V.sub.BOOST2 to a second boosted voltage output 94.

[0038] The power management circuit 74 also includes first buck circuitry 96, second buck circuitry 98, first switcher circuitry 100, and second switcher circuitry 102. Collectively, the first voltage boost circuitry 76, the first buck circuitry 96, and the first switcher circuitry 100 are hereinafter referred to as a first voltage distribution circuit 104. Similarly, the second voltage boost circuitry 78, the second buck circuitry 98, and the second switcher circuitry 102 are hereinafter referred to as a second voltage distribution circuit 106.

[0039] The first switcher circuitry 100 is coupled to the first voltage boost circuitry 76 and the first buck circuitry 96. The second switcher circuitry 102 is coupled to the second voltage boost circuitry 78 and the second buck circuitry 98. The control circuit 80 is configured to be communicatively coupled to the first switcher circuitry 100 and the second switcher circuitry 102. In this regard, when the control circuit 80 determines that the second envelope tracking amplifier 60 is the selected envelope tracking amplifier in need of the boosted voltage, the control circuit 80 can control the first switcher circuitry 100 to provide the first boosted voltage V.sub.BOOST1 to the second envelope tracking amplifier 60. Likewise, when the control circuit 80 determines that the first envelope tracking amplifier 58 is the selected envelope tracking amplifier in need of the boosted voltage, the control circuit 80 can control the second switcher circuitry 102 to provide the second boosted voltage V.sub.BOOST2 to the first envelope tracking amplifier 58. In addition, the control circuit 80 can control the first switcher circuitry 100 to provide the first supply voltage V.sub.BAT1 to the first buck circuitry 96 as a first input voltage V.sub.IN1. Likewise, the control circuit 80 can also control the second switcher circuitry 102 to provide the second supply voltage V.sub.BAT2 to the second buck circuitry 98 as a second input voltage V.sub.IN2.

[0040] To help understand how the first switcher circuitry 100 and the second switcher circuitry 102 can be controlled to distribute the boosted voltage, FIG. 3 is discussed next. In this regard, FIG. 3 is a schematic diagram of an exemplary voltage distribution circuit 108 that can be provided in the envelope tracking power management circuit 56 of FIG. 2 as the first voltage distribution circuit 104 and the second voltage distribution circuit 106. Common elements between FIGS. 2 and 3 are shown therein with common element numbers and will not be re-described herein.

[0041] With reference to FIG. 3, the voltage distribution circuit 108 includes voltage boost circuitry 110 that is functionally equivalent to the first voltage boost circuitry 76 and the second voltage boost circuitry 78 of FIG. 2. The voltage distribution circuit 108 includes buck circuitry 112 that is functionally equivalent to the first buck circuitry 96 and the second buck circuitry 98 of FIG. 2. The voltage distribution circuit 108 includes switcher circuitry 114 that is functionally equivalent to the first switcher circuitry 100 and the second switcher circuitry 102 of FIG. 2. As such, the voltage distribution circuit 108 can be provided in the envelope tracking power management circuit 56 as the first voltage distribution circuit 104 and/or the second voltage distribution circuit 106.

[0042] The voltage boost circuitry 110 includes switches SW1, SW2, SW3, and SW4. The switcher circuitry 114 includes switches SW5, SW6, SW7, and SW8. The voltage boost circuitry 110 can be configured to generate a boosted voltage V.sub.BOOST, which can be either the first boosted voltage V.sub.BOOST1 or the second boosted voltage V.sub.BOOST2 of FIG. 2, and provide the boosted voltage V.sub.BOOST to a boosted voltage output 116, which can be either the first boosted voltage output 92 or the second boosted voltage output 94 of FIG. 2. The voltage boost circuitry 110 is first controlled to charge a capacitor 118 to a supply voltage V.sub.BAT, which can be either the first supply voltage V.sub.BAT1 or the second supply voltage V.sub.BAT2 of FIG. 2, for example. To do so, the voltage boost circuitry 110 is controlled to close the switches SW1 and SW4, while keeping the rest of the switches open. Accordingly, a charging current I.sub.CHARGE can be induced to charge the capacitor 118 to the supply voltage V.sub.BAT.

[0043] To generate the boosted voltage V.sub.BOOST at the boosted voltage output 116, the switcher circuitry 114 is controlled to close the switch SW3, while keeping the rest of the switches open. As such, the boosted voltage V.sub.BOOST at the boosted voltage output 116 will equal a sum of the voltage of the capacitor 118, which has been charged to the supply voltage V.sub.BAT, and a voltage V′.sub.BAT drawn from a battery 120 (V.sub.BOOST=V.sub.BAT+V′.sub.BAT). If the voltage V′.sub.BAT is less than or equal to the supply voltage V.sub.BAT, the boosted voltage V.sub.BOOST will be less than or equal to two times the supply voltage V.sub.BAT (V.sub.BOOST≦2*V.sub.BAT). In this regard, when the voltage boost circuitry 110 is provided in the power management circuit 74 as the first voltage boost circuitry 76 and the second voltage boost circuitry 78, the first voltage boost circuitry 76 can generate the first boosted voltage V.sub.BOOST1 as being greater than or equal to the first supply voltage V.sub.BAT1, and the second voltage boost circuitry 78 can generate the second boosted voltage V.sub.BOOST2 as being greater than or equal to the second supply voltage V.sub.BAT2. The switcher circuitry 114 is further controlled to close the switch SW5 to output the boosted voltage V.sub.BOOST from the boosted voltage output 116.

[0044] The buck circuitry 112 includes an inductor 122. The buck circuitry 112 is configured to generate an electrical current I based on an input voltage V.sub.IN, which is equivalent to the first input voltage V.sub.IN1 or the second input voltage V.sub.IN2 of FIG. 2. In one non-limiting example, the switcher circuitry 114 can be controlled to close the switch SW7 to provide the supply voltage V.sub.BAT to the buck circuitry 112 as the input voltage V.sub.IN, while keeping the switches SW3 and SW5 closed to output the boosted voltage V.sub.BOOST from the boosted voltage output 116. In another non-limiting example, the switcher circuitry 114 can be controlled to close the switches SW2 and SW3 to provide the boosted voltage V.sub.BOOST to the buck circuitry 112 as the input voltage V.sub.IN, while keeping the switch SW5 closed to output the boosted voltage V.sub.BOOST from the boosted voltage output 116. In this regard, the electrical current I can vary as a function of the input voltage V.sub.IN. The electrical current I may be maximized when the input voltage V.sub.IN is the boosted voltage V.sub.BOOST.

[0045] The buck circuitry 112 can be controlled to output the electrical current I to a coupling point 124, which is equivalent to the first coupling point 85 and the second coupling point 88 of FIG. 2. The buck circuitry 112 may include a bypass switch SW9 and a bypass capacitor 126. The buck circuitry 112 can be controlled to close the bypass switch SW9 to prevent the electrical current I from being provided to the coupling point 124. In this regard, when the buck circuitry 112 is configured to function as the first buck circuitry 96 of FIG. 2, the buck circuitry 112 generates the first electrical current I.sub.1 based on the first input voltage V.sub.IN1 and provides the first electrical current I.sub.1 to the first RF transmission circuit 66. Likewise, when the buck circuitry 112 is configured to function as the second buck circuitry 98 of FIG. 2, the buck circuitry 112 generates the second electrical current I.sub.2 based on the second input voltage V.sub.IN2 and provides the second electrical current I.sub.2 to the second RF transmission circuit 72.

[0046] With reference back to FIG. 2, the first RF signal 62 received by the first RF transmission circuit 66 has a first power P.sub.1 that is a function of the first electrical current I.sub.1 and the modified first voltage V′.sub.1 (P.sub.1=I.sub.1*V′.sub.1). The first RF transmission circuit 66 may include at least one first power amplifier 128 configured to cause the first RF signal 62 to be transmitted at a first transmit power P.sub.TX1 (P.sub.TX1≦P.sub.1) in the first RF carrier. Likewise, the second RF signal 68 received by the second RF transmission circuit 72 has a second power P.sub.2 that is a function of the second electrical current I.sub.2 and the modified second voltage V′.sub.2 (P.sub.2=I.sub.2*V′.sub.2). The second RF transmission circuit 72 may include at least one second power amplifier 130 configured to cause the second RF signal 68 to be transmitted at a second transmit power P.sub.TX2 (P.sub.TX2≦P.sub.2) in the second RF carrier.

[0047] The first RF carrier and the second RF carrier may be located in licensed RF spectrums. As such, an average total power P.sub.TOTAL of the first transmit power P.sub.TX1 and the second transmit power P.sub.TX2 may be subject to an average power limit determined by standard organizations and/or regulatory authorities. For example, if the first RF signal 62 and the second RF signal 68 are transmitted in the LTE system, the average total power P.sub.TOTAL will need to stay below an average total power limit of 23 dBm.

[0048] In compliance with the 23 dBm average total power limit, exemplary relationships between the first transmit power P.sub.TX1, the second transmit power P.sub.TX2, and the average total power P.sub.TOTAL are provided in Table 1 below. The exemplary relationships in Table 1 referenced hereinafter help demonstrate the rationale behind reconfiguring the first voltage boost circuitry 76 or the second voltage boost circuitry 78 to provide the boosted voltage to the selected envelope tracking amplifier.

TABLE-US-00001 TABLE 1 P.sub.TX1 (dBm) P.sub.TX2 (dBm) P.sub.TOTAL (dBm) BK1 (dB) BK2 (dB) 23 −10 23 0 33 22.2 15 23 0.8 8 −10 23 23 33 0

[0049] According to Table 1, when the first transmit power P.sub.TX1 is at 23 dBm, the second transmit power P.sub.TX2 needs to be around −10 dBm to satisfy the 23 dBm average total power limit. As such, the first power amplifier 128 has a first power back-off BK1 of 0 dB, and the second power amplifier 130 has a second power back-off BK2 of 33 dB. When the first transmit power P.sub.TX1 is at 22.2 dBm, the second transmit power P.sub.TX2 needs to be at 15 dBm or below to satisfy the 23 dBm average total power limit. Accordingly, the first power amplifier 128 has a first power back-off BK1 of 0.8 dB, and the second power amplifier 130 has a second power back-off BK2 of 8 dB. When the second transmit power P.sub.TX2 is at 23 dBm, the first transmit power P.sub.TX1 needs to be around −10 dBm to satisfy the 23 dBm average total power limit. As such, the first power amplifier 128 has a first power back-off BK1 of 33 dB, and the second power amplifier 130 has a second power back-off BK2 of 0 dB.

[0050] The first power amplifier 128 may have a first load-line voltage V.sub.L1 and a first threshold voltage V.sub.knee1. In this regard, the modified first voltage V′.sub.1 required to cause the first power amplifier 128 to amplify the first RF signal 62 to the first transmit power P.sub.TX1 in Table 1 can be determined based on the equation (Eq. 2) below.

[00001] $\begin{matrix} V_{1}^{'} = 10^{- (\frac{BK .Math. .Math. 1}{20}) ⋆} .Math. (V_{L .Math. .Math. 1} - V_{knee .Math. .Math. 1}) + V_{knee .Math. .Math. 1} & (Eq . .Math. 2) \end{matrix}$

[0051] In a non-limiting example, the first load-line voltage V.sub.L1 and the first threshold voltage V.sub.knee1 can be 4.2 V and 0.5 V, respectively. Accordingly, the equation (Eq. 2) can be simplified as follows.

[00002] $\begin{matrix} V_{1}^{'} = (10^{- (\frac{BK .Math. .Math. 1}{20})}) ⋆ 3.7 + 0.5 & (Eq . .Math. 2.1) \end{matrix}$

[0052] Accordingly, the first voltage V.sub.1 generated by the first envelope tracking amplifier 58 can be determined by the equation (Eq. 3) below.

V.sub.1=V′.sub.1−V.sub.C1+P.sub.Headroom1 (Eq. 3)

[0053] In the equation (Eq. 3) above, V.sub.C1 is the first offset voltage produced by the first offset capacitor 86, and P.sub.Headroom1 is a voltage corresponding to a peak of the first electrical current I.sub.1 generated by the first buck circuitry 96. In a non-limiting example, the first offset voltage V.sub.C1 and the voltage P.sub.Headroom1 can be 0.8V and 0.3V, respectively. Accordingly, the equation (Eq. 3) can be simplified as follows.

V.sub.1=V′.sub.1−0.5 (Eq. 3.1)

[0054] Likewise, the second power amplifier 130 may have a second load-line voltage V.sub.L2 and a second threshold voltage V.sub.knee2. In this regard, the modified second voltage V′.sub.2 required to cause the second power amplifier 130 to amplify the second RF signal 68 to the second transmit power P.sub.TX2 in Table 1 can be computed based on the equation (Eq. 4) below.

[00003] $\begin{matrix} V_{2}^{'} = 10^{- (\frac{BK .Math. .Math. 2}{20}) ⋆} .Math. (V_{L .Math. .Math. 2} - V_{knee .Math. .Math. 2}) + V_{knee .Math. .Math. 2} & (Eq . .Math. 4) \end{matrix}$

[0055] In a non-limiting example, the second load-line voltage V.sub.L2 and the second threshold voltage V.sub.knee2 can be 4.2 V and 0.5 V, respectively. Accordingly, the equation (Eq. 4) can be simplified as follows.

[00004] $\begin{matrix} V_{2}^{'} = (10^{- (\frac{BK .Math. .Math. 2}{20})}) ⋆ 3.7 + 0.5 & (Eq . .Math. 4.1) \end{matrix}$

[0056] Accordingly, the second voltage V.sub.2 generated by the second envelope tracking amplifier 60 can be determined by the equation (Eq. 5) below.

V.sub.2=V′.sub.2−V.sub.C2+P.sub.Headroom2 (Eq. 5)

[0057] In the equation (Eq. 5) above, V.sub.C2 is the second offset voltage produced by the second offset capacitor 90, and P.sub.Headroom2 is a voltage corresponding to a peak of the second electrical current I.sub.2 generated by the second buck circuitry 98. In a non-limiting example, the second offset voltage V.sub.C2 and the voltage P.sub.Headroom2 can be 0.8V and 0.3V, respectively. Accordingly, the equation (Eq. 5) can be simplified as follows.

V.sub.2=V′.sub.2−0.5 (Eq. 5.1)

[0058] Table 2 illustrates relationships between the first voltage V.sub.1, the second voltage V.sub.2, the first transmit power P.sub.TX1, and the second transmit power P.sub.TX2 as determined based on equations Eq. 2.1, Eq. 3.1, Eq. 4.1, and Eq. 5.1.

TABLE-US-00002 TABLE 2 P.sub.TX1 P.sub.TX2 BK1 BK2 V′.sub.1 V′.sub.2 V.sub.1 V.sub.2 (dBm) (dBm) (dB) (dB) (V) (V) (V) (V) 23 −10 0 33 4.2 0.58 3.7 0.08 22.2 15 0.8 8 3.87 1.97 3.37 1.47 −10 23 33 0 0.58 4.2 0.08 3.7

[0059] According to Table 2, when the first RF signal 62 is transmitted at the first transmit power P.sub.TX1 of 23 dBm, the first envelope tracking amplifier 58 needs to amplify the first RF signal 62 to the first voltage V.sub.1 of 3.7 V. Accordingly, the first supply voltage V.sub.BAT1 also needs to be at least 3.7 V. As previously discussed, the first supply voltage V.sub.BAT1 may be only 3.4 V. In this regard, the first supply voltage V.sub.BAT1 will be lower than the voltage (e.g., 3.7 V) required for amplifying the first RF signal 62 to the predetermined voltage. However, given that the second RF signal 68 is required to be transmitted at the second transmit power P.sub.TX2 of −10 dBm, the second envelope tracking amplifier 60 only needs to amplify the second RF signal 68 to the second voltage V.sub.2 of 0.08 V. In this regard, the second supply voltage V.sub.BAT2, which is at 3.4 V as previously discussed, will be higher than the voltage (0.08 V) required for amplifying the second RF signal 68 to the predetermined voltage. Therefore, the control circuit 80 can control the second switcher circuitry 102 and the second voltage boost circuitry 78 to provide the second boosted voltage V.sub.BOOST2 to the first envelope tracking amplifier 58. As a result, the first envelope tracking amplifier 58 would be able to amplify the first RF signal 62 to the first voltage V.sub.1 of 3.7 V and consequently cause the first RF signal 62 to be transmitted at the first transmit power P.sub.TX1 of 23 dBm.

[0060] When the first RF signal 62 is transmitted at the first transmit power P.sub.TX1 of 22.2 dBm, the first envelope tracking amplifier 58 needs to amplify the first RF signal 62 to the first voltage V.sub.1 of 3.37 V. Accordingly, the first supply voltage V.sub.BAT1 also needs to be at least 3.37 V. In this regard, the first supply voltage V.sub.BAT1, which is 3.4 V, is higher than the voltage (3.37 V) required for amplifying the first RF signal 62 to the predetermined voltage. As such, the first envelope tracking amplifier 58 does not require the boosted voltage. The second RF signal 68, on the other hand, is transmitted at the second transmit power P.sub.TX2 of 15 dBm. Accordingly, the second envelope tracking amplifier 60 only needs to amplify the second RF signal 68 to the second voltage V.sub.2 of 1.47 V, which is lower than the second supply voltage V.sub.BAT2 (3.4 V). Therefore, the second envelope tracking amplifier 60 also does not require the boosted voltage.

[0061] Based on the analysis presented above, it can be concluded that, at any given time, no more than one of the first envelope tracking amplifier 58 and the second envelope tracking amplifier 60 would require the boosted voltage. In this regard, in response to determining that the first envelope tracking amplifier 58 receives the first supply voltage V.sub.BAT1 that is lower than the voltage required to amplify the first RF signal 62 to the predetermined voltage, the control circuit 80 can couple the second boosted voltage output 94 of the second voltage boost circuitry 78 to the first supply voltage input 64 to provide the second boosted voltage V.sub.BOOST2 to the first envelope tracking amplifier 58. Likewise, in response to determining that the second envelope tracking amplifier 60 receives the second supply voltage V.sub.BAT2 that is lower than the voltage required to amplify the second RF signal 68 to the predetermined voltage, the control circuit 80 can couple the first boosted voltage output 92 of the first voltage boost circuitry 76 to the second supply voltage input 70 to provide the first boosted voltage V.sub.BOOST1 to the second envelope tracking amplifier 60.

[0062] With continuing reference to FIG. 2, the power management circuit 74 may include first low drop-off output (LDO) circuitry 132 coupled to the first supply voltage input 64 of the first envelope tracking amplifier 58. In this regard, the control circuit 80 is configured to couple the second boosted voltage output 94 of the second voltage boost circuitry 78 to the first LDO circuitry 132 to provide the second boosted voltage V.sub.BOOST2 to the first envelope tracking amplifier 58. The power management circuit 74 may include second LDO circuitry 134 coupled to the second supply voltage input 70 of the second envelope tracking amplifier 60. In this regard, the control circuit 80 is configured to couple the first boosted voltage output 92 of the first voltage boost circuitry 76 to the second LDO circuitry 134 to provide the first boosted voltage V.sub.BOOST1 to the second envelope tracking amplifier 60.

[0063] By providing the first boosted voltage V.sub.BOOST1 and the second boosted voltage V.sub.BOOST2 through the second LDO circuitry 134 and the first LDO circuitry 132, respectively, it is possible to simplify the switcher circuitry 114 of FIG. 3. In this regard, FIG. 4 is a schematic diagram of an exemplary simplified voltage distribution circuit 136 that can be provided in the envelope tracking power management circuit 56 of FIG. 2 as the first voltage distribution circuit 104 and the second voltage distribution circuit 106. Common elements between FIGS. 2-4 are shown therein with common element numbers and will not be re-described herein.

[0064] The simplified voltage distribution circuit 136 includes switcher circuitry 138 that can be provided in the power management circuit 74 of FIG. 2 as the first switcher circuitry 100 and/or the second switcher circuitry 102. The switcher circuitry 138 is simplified from the switcher circuitry 114 of FIG. 3 by eliminating the switches SW5 and SW6. In the regard, the boosted voltage output 116, which can be either the first boosted voltage output 92 or the second boosted voltage output 94, is always outputting the boosted voltage V.sub.BOOST.

[0065] With reference back to FIG. 2, the first LDO circuitry 132 and the second LDO circuitry 134 can be collocated with additional LDO circuitries dedicated for supplying the boosted voltage to the first envelope tracking amplifier 58 and the second envelope tracking amplifier 60. In this regard, FIG. 5 is a schematic diagram of an exemplary LDO circuit 140 including LDO circuitry 142 configured to receive a supply voltage V.sub.BAT, and boosted LDO circuitry 144 configured to receive a boosted voltage V.sub.BOOST higher than the supply voltage V.sub.BAT.

[0066] The LDO circuitry 142 is functionally equivalent to the first LDO circuitry 132 and the second LDO circuitry 134 of FIG. 2. In this regard, the LDO circuitry 142 can be provided as the first LDO circuitry 132 in the power management circuit 74 of FIG. 2 to provide the first supply voltage V.sub.BAT1 to the first supply voltage input 64. Likewise, the LDO circuitry 142 can be provided as the second LDO circuitry 134 in the power management circuit 74 of FIG. 2 to provide the second supply voltage V.sub.BAT2 to the second supply voltage input 70. The LDO circuitry 142 and the boosted LDO circuitry 144 are both coupled to a DC source 146, which can be either the first DC source 82 or the second DC source 84 of FIG. 2. The boosted LDO circuitry 144 is configured to receive the boosted voltage V.sub.BOOST, which can be the first boosted voltage V.sub.BOOST1 or the second boosted voltage V.sub.BOOST2 of FIG. 2. The LDO circuit 140 is configured to output either the supply voltage V.sub.BAT or the boosted voltage V.sub.BOOST to a supply voltage input 148, which can be the first supply voltage input 64 or the second supply voltage input 70 of FIG. 2.

[0067] As previously discussed in FIG. 2, the first voltage boost circuitry 76 can generate the first boosted voltage V.sub.BOOST1 that is between the first supply voltage V.sub.BAT1 and two times the first supply voltage V.sub.BAT1 (V.sub.BAT1≦V.sub.BOOST1≦2*V.sub.BAT1), and the second voltage boost circuitry 78 can generate the second boosted voltage V.sub.BOOST2 that is between the second supply voltage V.sub.BAT2 and two times the second supply voltage V.sub.BAT2 (V.sub.BAT2≦V.sub.BOOST2≦2*V.sub.BAT2). If the first supply voltage V.sub.BAT1 and the second supply voltage V.sub.BAT2 are both 3.4 V, for example, the first boosted voltage V.sub.BOOST1 and the second boosted voltage V.sub.BOOST2 can both be up to 6.8 V. As a result, the first boosted voltage V.sub.BOOST1 and/or the second boosted voltage V.sub.BOOST2 may be too high for the second envelope tracking amplifier 60 and/or the first envelope tracking amplifier 58 to tolerate. As such, it may be desired to regulate the first boosted voltage V.sub.BOOST1 and/or the second boosted voltage V.sub.BOOST2. In this regard, FIG. 6 is a schematic diagram of an exemplary voltage regulating circuit 150 configured to regulate the first boosted voltage V.sub.BOOST1 and the second boosted voltage V.sub.BOOST2 of FIG. 2.

[0068] With reference to FIG. 6, the voltage regulating circuit 150 includes a p-type metal-oxide semiconductor field-effect transistor (pMOSFET) 152 having a drain electrode 154 coupled to voltage boost circuitry 156. The voltage boost circuitry 156 can be the first voltage boost circuitry 76 or the second voltage boost circuitry 78 of FIG. 2. In this regard, the pMOSFET 152 can be provided in the power management circuit 74 of FIG. 2 to regulate the first boosted voltage V.sub.BOOST1 generated by the first voltage boost circuitry 76 and/or the second boosted voltage V.sub.BOOST2 generated by the second voltage boost circuitry 78.

[0069] The pMOSFET 152 receives a boosted voltage V.sub.BOOST, which can be either the first boosted voltage V.sub.BOOST1 or the second boosted voltage V.sub.BOOST2, from the voltage boost circuitry 156. The pMOSFET 152 has a gate electrode 158 coupled to an LDO controller 160. The LDO controller 160 is coupled to a DC source 162, which can be either the first DC source 82 or the second DC source 84 of FIG. 2. The LDO controller 160 is configured to adjust a voltage applied to the gate electrode 158, thus regulating the boosted voltage V.sub.BOOST received on the drain electrode 154 to produce a regulated boosted voltage V.sub.R. The pMOSFET 152 has a source electrode 164 configured to output the regulated boosted voltage V.sub.R. In this regard, when the pMOSFET 152 is coupled to the first voltage boost circuitry 76, the pMOSFET 152 regulates the first boosted voltage V.sub.BOOST1. Likewise, when the pMOSFET 152 is coupled to the second voltage boost circuitry 78, the pMOSFET 152 regulates the second boosted voltage V.sub.BOOST2.

[0070] With reference back to FIG. 2, the first envelope tracking amplifier 58 may be controlled by a first envelope tracking controller 166 to amplify the first RF signal 62 based on a first envelope tracking feedback signal 168. Likewise, the second envelope tracking amplifier 60 can be controlled by a second envelope tracking controller 170 to amplify the second RF signal 68 based on a second envelope tracking feedback signal 172.

[0071] The first RF signal 62 may include a first low-band RF signal 174 and a first mid-band RF signal 176. As such, the first RF transmission circuit 66 may include a first low-band transmission circuit 178 and a first mid-band transmission circuit 180 configured to transmit the first low-band RF signal 174 and the first mid-band RF signal 176, respectively.

[0072] The second RF signal 68 may include a second mid-band RF signal 182 and a second high-band RF signal 184. As such, the second RF transmission circuit 72 may include a second mid-band transmission circuit 186 and a second high-band transmission circuit 188 configured to transmit the second mid-band RF signal 182 and the second high-band RF signal 184, respectively.

[0073] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

ENVELOPE TRACKING POWER MANAGEMENT CIRCUIT

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