# Patent

## Title
Power management architecture for modulated and constant supply operation

## Abstract

A power management system, which includes a parallel amplifier circuit and a switch mode power supply converter, is disclosed. The switch mode power supply converter cooperatively operates with the parallel amplifier circuit to form the power management system. The power management system operates in one of a high power modulation mode, a medium power modulation mode, and a low power average power tracking mode. Further, during the high power modulation mode and the medium power modulation mode, the power management system controls a power amplifier supply voltage to a radio frequency power amplifier to provide envelope tracking. During the low power average power tracking mode, the power management system controls the power amplifier supply voltage to the radio frequency power amplifier to provide average power tracking.

## Background
RELATED APPLICATIONS
The present application claims priority to and is a continuation-in-part of International Patent Application No. PCT/US12/36858, filed May 7, 2012, entitled “POWER MANAGEMENT SYSTEM FOR PSEUDO-ENVELOPE AND AVERAGE POWER TRACKING,” which claims priority to U.S. Provisional Patent Applications No. 61/482,702, filed May 5, 2011; No. 61/484,613, filed May 10, 2011; No. 61/508,202, filed Jul. 15, 2011; No. 61/530,625, filed Sep. 2, 2011; No. 61/544,051, filed Oct. 06, 2011; No. 61/551,605, filed Oct. 26, 2011; No. 61/565,138, filed Nov. 30, 2011; and No. 61/576,520, filed Dec. 16, 2011.
International Patent Application No. PCT/US12/36858, filed May 7, 2012, claims priority to and is a continuation-in-part of U.S. patent application Ser. No. 13/218,400, filed Aug. 25, 2011, entitled “BOOST CHARGE-PUMP WITH FRACTIONAL RATIO AND OFFSET LOOP FOR SUPPLY MODULATION,” now U.S. Pat. No. 8,519,788, which was also filed as International Patent Application No. PCT/US11/49243 on Aug. 25, 2011.
International Patent Application No. PCT/US12/36858, filed May 7, 2012, claims priority to and is a continuation-in-part of International Patent Application No. PCT/US11/54106, filed Sep. 29, 2011, entitled “SINGLE μC-BUCKBOOST CONVERTER WITH MULTIPLE REGULATED SUPPLY OUTPUTS.”
International Patent Application No. PCT/US12/36858, filed May 7, 2012, claims priority to and is a continuation-in-part of U.S. patent application Ser. No. 13/316,229, filed Dec. 9, 2011, entitled “PSEUDO-ENVELOPE FOLLOWER POWER MANAGEMENT SYSTEM WITH HIGH FREQUENCY RIPPLE CURRENT,” now U.S. Pat. No. 8,633,766, which was also filed as International Patent Application No. PCT/US11/64255 on Dec. 9, 2011. U.S. patent application Ser. No. 13/316,229, filed Dec. 9, 2011, is a continuation-in-part of U.S. patent application Ser. No. 13/218,400, filed Aug. 25, 2011, which was also filed as International Patent Application No. PCT/US11/49243 on Aug. 25, 2011.
International Patent Application No. PCT/US12/36858, filed May 7, 2012, claims priority to and is a continuation-in-part of U.S. patent application Ser. No. 13/367,973, filed Feb. 7, 2012, entitled “GROUP DELAY CALIBRATION METHOD FOR POWER AMPLIFIER ENVELOPE TRACKING,” now U.S. Pat. No. 8,942,313, which was also filed as International Patent Application No. PCT/US12/24124 on Feb. 7, 2012.
International Patent Application No. PCT/US12/36858, filed May 7, 2012, claims priority to and is a continuation-in-part of U.S. patent application Ser. No. 13/423,649, filed Mar. 19, 2012, entitled “APPARATUSES AND METHODS FOR RATE CONVERSION AND FRACTIONAL DELAY CALCULATION USING A COEFFICIENT LOOK UP TABLE,” now U.S. Pat. No. 8,624,760.
International Patent Application No. PCT/US12/36858, filed May 7, 2012, claims priority to and is a continuation-in-part of U.S. patent application Ser. No. 13/363,888, filed Feb. 1, 2012, entitled “FAST ENVELOPE SYSTEM CALIBRATION,” now U.S. Pat. No. 8,611,402, which was also filed as International Patent Application No. PCT/US12/23495, on Feb. 1, 2012.
All of the applications listed above are hereby incorporated herein by reference in their entireties.


FIELD OF THE DISCLOSURE
The embodiments described herein relate to a power management system for delivering current to a linear radio frequency power amplifier. More particularly, the embodiments relate to the use of a pseudo-envelope tracker in a power management system of mobile communications equipment.
BACKGROUND
Next-generation mobile devices are morphing from voice-centric telephones to message and multimedia-based “smart” phones that offer attractive new features. As an example, smart phones offer robust multimedia features such as web-browsing, audio and video playback and streaming, email access and a rich gaming environment. But even as manufacturers race to deliver ever more feature rich mobile devices, the challenge of powering them looms large.
In particular, the impressive growth of high bandwidth applications for radio frequency (RF) hand-held devices has led to increased demand for efficient power saving techniques to increase battery life. Because the radio frequency power amplifier of the mobile device consumes a large percentage of the overall power budget of the mobile device, various power management systems have been proposed to increase the overall power efficiency of the radio frequency power amplifier. As such, there remains a need to further improve the power efficiency of mobile devices to provide extended battery life. In this regard, there is a need to improve the power management system of mobile devices.
SUMMARY
A power management system, which includes a parallel amplifier circuit and a switch mode power supply converter, is disclosed according to one embodiment of the present disclosure. The switch mode power supply converter cooperatively operates with the parallel amplifier circuit to form the power management system. The power management system operates in one of a high power modulation mode, a medium power modulation mode, and a low power average power tracking mode. Further, during the high power modulation mode and the medium power modulation mode, the power management system controls a power amplifier supply voltage to a radio frequency power amplifier to provide envelope tracking. During the low power average power tracking mode, the power management system controls the power amplifier supply voltage to the radio frequency power amplifier to provide average power tracking.
Those skilled in the art will appreciate the scope of the disclosure and realize additional aspects thereof after reading the following detailed description in association with the accompanying drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
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.
FIG. 1A depicts an embodiment of a pseudo-envelope follower power management system for managing power supplied to a linear radio frequency power amplifier according to one embodiment of the pseudo-envelope follower power management system.
FIG. 1B depicts an embodiment of the pseudo-envelope follower power management system for managing power supplied to a linear radio frequency power amplifier according to an alternate embodiment of the pseudo-envelope follower power management system.
FIG. 2A depicts one embodiment of a pseudo-envelope tracking modulated power supply system according to one embodiment of the pseudo-envelope tracking modulated power supply system.
FIG. 2B depicts one embodiment of a pseudo-envelope tracking modulated power supply system according to an alternate embodiment of the pseudo-envelope tracking modulated power supply system.
FIG. 2C depicts one embodiment of a pseudo-envelope tracking modulated power supply system according to an additional embodiment of the pseudo-envelope tracking modulated power supply system.
FIG. 3 depicts a method for operating the pseudo-envelope tracking modulated power supply system according to one embodiment of the pseudo-envelope tracking modulated power supply system.



DETAILED DESCRIPTION
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.
A power management system, which includes a parallel amplifier circuit and a switch mode power supply converter, is disclosed according to one embodiment of the present disclosure. The switch mode power supply converter cooperatively operates with the parallel amplifier circuit to form the power management system. The power management system operates in one of a high power modulation mode, a medium power modulation mode, and a low power average power tracking mode. Further, during the high power modulation mode and the medium power modulation mode, the power management system provides a power amplifier supply voltage to a radio frequency power amplifier to provide envelope tracking. During the low power average power tracking mode, the power management system provides the power amplifier supply voltage to the radio frequency power amplifier to provide average power tracking.
FIG. 1A depicts an embodiment of a pseudo-envelope follower power management system 10A for managing power supplied to a linear radio frequency power amplifier 22 according to one embodiment of the pseudo-envelope follower power management system 10A. FIG. 1B depicts an embodiment of the pseudo-envelope follower power management system 10B for managing power supplied to the linear radio frequency power amplifier 22 according to an alternate embodiment of the pseudo-envelope follower power management system 10B. As such, FIGS. 1A and 2A depict an example embodiment of the pseudo-envelope follower power management system 10A including a multi-level charge pump buck converter 12, a parallel amplifier circuit 14, a power inductor 16, a coupling circuit 18, and a bypass capacitor 19. The bypass capacitor 19 has a bypass capacitor capacitance, CBYPASS.
The multi-level charge pump buck converter 12 and the parallel amplifier circuit 14 may be configured to operate in tandem to generate a power amplifier supply voltage, VCC, at a power amplifier supply output 28 of the pseudo-envelope follower power management system 10A for the linear radio frequency power amplifier 22. The power amplifier supply voltage, VCC, may also be referred to as a modulated power supply voltage, VCC. The power amplifier supply output 28 provides an output current, IOUT, to the linear radio frequency power amplifier 22. The linear radio frequency power amplifier 22 may include a radio frequency power amplifier input configured to receive a modulated radio frequency input signal having an input power PIN. The linear radio frequency power amplifier 22 may further include a radio frequency power amplifier output coupled to an output load, ZLOAD. The linear radio frequency power amplifier 22 may generate an amplified modulated radio frequency output signal having an output power POUT in response to the modulated radio frequency input signal having the input power PIN.
As an example, the output load, ZLOAD, may be an antenna. The radio frequency power amplifier output may generate the amplified modulated radio frequency output signal as a function of the modulated radio frequency input signal and the power amplifier supply voltage, VCC. In some embodiments, the power amplifier supply voltage, VCC, may be modulated to substantially follow the signal envelope characteristic of the modulated radio frequency input signal to improve the power efficiency of the pseudo-envelope follower power management system 10A. The amplified modulated radio frequency output signal may be provided to the antenna for transmission. The multi-level charge pump buck converter 12 may include a supply input 24, (VBAT), configured to receive a battery voltage, VBAT, from a battery 20 and a switching voltage output 26 configured to provide a switching voltage, VSW. The switching voltage output 26 may be coupled to the power amplifier supply output 28 by the power inductor 16, where the power inductor 16 couples to the bypass capacitor 19 to form an output filter 29 for the switching voltage output 26 of the multi-level charge pump buck converter 12. As such, the power inductor 16 is coupled between the switching voltage output 26 and the power amplifier supply output 28. The power inductor 16 provides a power inductor current, ISW—OUT, to the power amplifier supply output 28. The parallel amplifier circuit 14 may include a parallel amplifier supply input 30 configured to receive the battery voltage, VBAT, from the battery 20, a parallel amplifier output 32A, a first control input 34 configured to receive a VRAMP signal, and a second control input configured to receive the power amplifier supply voltage, VCC. The parallel amplifier output 32A of the parallel amplifier circuit 14 may be coupled to the power amplifier supply voltage VCC, by the coupling circuit 18. A parallel amplifier output voltage, VPARA—AMP, is provided by the parallel amplifier circuit 14.
As an example, the parallel amplifier circuit 14 may generate the parallel amplifier output voltage, VPARA—AMP, based on the difference between the VRAMP signal and the power amplifier supply voltage, VCC. Thus, the VRAMP signal may represent either an analog or digital signal that contains the required supply modulation information for a power amplifier collector of a linear radio frequency power amplifier. Typically, the VRAMP signal is provided to the parallel amplifier circuit 14 as a differential analog signal to provide common mode rejection against any noise or spurs that could appear on this signal. The VRAMP signal may be a time domain signal, VRAMP (t), generated by a transceiver or modem and used to transmit radio frequency signals. For example, the VRAMP signal may be generated by a digital baseband processing portion of the transceiver or modem, where the digital VRAMP signal, VRAMP—DIGITAL, is digital-to-analog converted to form the VRAMP signal in the analog domain. In some embodiments, the “analog” VRAMP signal is a differential signal. The transceiver or a modem may generate the VRAMP signal based upon a known radio frequency modulation Amp (t)*cos(2*pi*fRF*t+Phase (t)). The VRAMP signal may represent the target voltage for the power amplifier supply voltage, VCC, to be generated at the power amplifier supply output 28 of the pseudo-envelope follower power management system 10A, where the pseudo-envelope follower power management system 10A provides the power amplifier supply voltage, VCC, to the linear radio frequency power amplifier 22. Also the VRAMP signal may be generated from a detector coupled to the linear radio frequency power amplifier 22.
For example, the parallel amplifier circuit 14 includes the parallel amplifier output 32A that provides the parallel amplifier output voltage, V-PARA—AMP, to the coupling circuit 18. The parallel amplifier output 32A sources a parallel amplifier circuit output current, IPAWA—OUT, to the coupling circuit 18. The parallel amplifier circuit 14, depicted in FIG. 1A and FIG. 1B, may provide a parallel amplifier circuit output current estimate 40, IPAWA—OUT—EST, to the multi-level charge pump buck converter 12 as an estimate of the parallel amplifier circuit output current IPAWA—OUT, of the parallel amplifier circuit 14. Thus, the parallel amplifier circuit output current estimate 40, IPAWA—OUT—EST, represents an estimate of the parallel amplifier circuit output current IPAWA—OUT, provided by the parallel amplifier circuit 14 as a feedback signal to the multi-level charge pump buck converter 12. Based on the parallel amplifier circuit output current estimate 40, IPAWA—OUT—EST, the multi-level charge pump buck converter 12 may be configured to control the switching voltage, VSW, provided at the switching voltage output 26 of the multi-level charge pump buck converter 12.
In some embodiments of the pseudo-envelope follower power management system 10A, depicted in FIG. 1A, and the pseudo-envelope follower power management system 10B, depicted in FIG. 1B, the coupling circuit 18 may be an offset capacitor, COFFSET. An offset voltage, VOFFSET, may be developed across the coupling circuit 18. In other alternative embodiments, the coupling circuit 18 may be a wire trace such that the offset voltage, VOFFSET, between the parallel amplifier output voltage, VPARA—AMP, and the power amplifier supply voltage output, VCC, is zero volts. In still other embodiments, the coupling circuit may be a transformer.
FIG. 2A depicts one embodiment of a pseudo-envelope tracking modulated power supply system 868 according to one embodiment of the pseudo-envelope tracking modulated power supply system 868.
FIG. 2B depicts one embodiment of a pseudo-envelope tracking modulated power supply system 868 according to an alternate embodiment of the pseudo-envelope tracking modulated power supply system 868.
FIG. 2C depicts one embodiment of a pseudo-envelope tracking modulated power supply system 868 according to an additional embodiment of the pseudo-envelope tracking modulated power supply system 868.
FIG. 2A depicts a high level illustration of a pseudo-envelope tracking modulated power supply system 868 that may include a radio frequency power amplifier 869 configured to be powered by or under the control of a power management system 870. The power amplifier supply voltage, VCC, may also be referred to as a modulated power supply voltage, VCC, that is generated at a modulated power supply output 876.
Similar to other previously described switch mode power supply converters, multi-level charge pump buck converters, and parallel amplifier circuits, a switch mode power supply converter 872 and a parallel amplifier circuit 874 may be configured to receive an input supply voltage from a battery 20. The battery 20 may provide a supply voltage substantially equal to the battery voltage, VBAT.
For the sake of simplicity of description, and not by way of limitation, the pseudo-envelope tracking modulated power supply system 868 may include a controller 50 coupled via a control bus 44 to the switch mode power supply converter 872 and the parallel amplifier circuit 874. The switch mode power supply converter 872 may be arranged to cooperatively operate with the parallel amplifier circuit 874 to form the power management system 870, which generates the modulated power supply voltage, VCC, at the modulated power supply output 876. For example, in some embodiments, the controller 50 may configure the switch mode power supply converter 872 and the parallel amplifier circuit 874 to operate in various power level modulation modes, depending upon the expected output power to be generated by the radio frequency power amplifier 869 during a transmission of information. In some embodiments, the control functions described with respect to the controller 50 may be incorporated into a digital baseband modem or transceiver circuit that provides a differential VRAMP signal as a control signal to the power management system 870 based on a radio frequency input signal provided to the radio frequency power amplifier 869 for transmission.
The power management system 870 may be configured to receive a differential VRAMP signal having a non-inverted VRAMP signal component, VRAMP+, and an inverted VRAMP signal component, VRAMP−. In some alternative embodiments, the power management system 870 may be configured to receive a VRAMP signal that is a single ended VRAMP signal, a differential VRAMP signal, and/or both the single ended VRAMP signal and the differential VRAMP signal. The differential VRAMP signal may be provided as a control signal to govern generation of the modulated power supply voltage, VCC. Illustratively, the switch mode power supply converter 872 and the parallel amplifier circuit 874 may each be configured to receive the differential VRAMP signal.
The switch mode power supply converter 872 may include the switching voltage output 26 in communication with the modulated power supply output 876. A power inductor 16 may be coupled between the switching voltage output 26 and the modulated power supply output 876.
The parallel amplifier circuit 874 may include a parallel amplifier circuit output 874A in communication with the modulated power supply output 876. Illustratively, in some embodiments, a coupling capacitor 18A is coupled between the modulated power supply output 876 and the parallel amplifier circuit output 874A. In addition, the parallel amplifier circuit 874 may also include a first linear regulator output 874B, LDO1 OUTPUT, in communication with the modulated power supply output 876. In some power level modulation modes, the power management system 870 may configure the first linear regulator output 874B, LDO1 OUTPUT, to provide a high impedance path with respect to ground. In other power level modulation modes, the power management system 870 may configure the first linear regulator output 874B, LDO1 OUTPUT, to apply a first linear regulator output current 878A, ILDO, to the modulated power supply output 876 to regulate the modulated power supply voltage, VCC.
The parallel amplifier circuit 874 may also include a second linear regulator output 874D, LDO2 OUTPUT, in communication with a CMOS logic supply input 869C. In some power level modulation modes, the power management system 870 may configure the second linear regulator output 874D, LDO2 OUTPUT, to provide a second linear regulator output voltage, VLDO2, to the CMOS logic supply input 869C as a function of the battery voltage, VBAT. As an example, the CMOS logic supply input 869C may include a minimum CMOS logic supply voltage threshold. Accordingly, the power management system 870 may configure the second linear regulator output 874D, LDO2 OUTPUT, to provide a second linear regulator output voltage, VVLDO2, to the CMOS logic supply input 869C that is at least equal to the minimum CMOS logic supply voltage threshold.
The parallel amplifier circuit 874 may also include a switch mode power supply converter control output 874E configured to output a switch mode power supply feedback signal 40A to the switch mode power supply converter 872, depicted in FIG. 2B. In addition, the parallel amplifier circuit 874 may provide a threshold offset current 42, ITHRESHOLD—OFFSET, to the switch mode power supply converter 872. The parallel amplifier circuit 874 may receive the modulated power supply voltage, VCC, from the modulated power supply output 876 at a modulated power supply voltage feedback input 874F. The parallel amplifier circuit 874 may use the input to the modulated power supply voltage feedback input 874F as a feedback signal to regulate the modulated power supply voltage, VCC.
In some embodiments, the radio frequency power amplifier 869 may be a linear radio frequency power amplifier. The radio frequency power amplifier 869 may include a radio frequency power amplifier input configured to receive a modulated radio frequency input signal from a digital baseband processing portion of the transceiver or modem, where the modulated radio frequency input signal has an input power, PIN. In addition, the radio frequency power amplifier 869 may also include a radio frequency power amplifier output in communication with an antenna via the radio frequency duplexer and switch (not shown). The radio frequency power amplifier 869 may generate an amplified modulated radio frequency output signal having an output power POUT at the radio frequency power amplifier output.
In some embodiments, the radio frequency power amplifier 869 may include a collector voltage supply input 869A configured to receive the modulated power supply voltage, VCC, from the modulated power supply output 876. The radio frequency power amplifier 869 may further include a battery voltage supply input 869B configured to receive the battery voltage, VBAT, from the battery 20. The radio frequency power amplifier 869 may also include a CMOS logic supply input 869C configured to receive a second linear regulator output voltage, VLDO2.
In some embodiments of the power management system 870, the power management system 870 may be configured to operate in various power level modulation modes based on an expected output power to be generated by the radio frequency power amplifier 869 during a data transmission. In addition, the power management system 870 may be reconfigured prior to each data transmission to minimize the energy drawn from the battery 20 during the data transmission. For example, some embodiments of the power management system 870 may be configured to operate in one of many power level modulation modes on a data transmission slot by data transmission slot basis.
As a non-limiting list of example power level modulation modes of operation, the power management system 870 may be configured to operate in a set of power level modulation modes including a high power modulation mode, a medium power modulation mode, and low power modulation mode. As another example, in other embodiments, the power management system 870 may be configured to operate in a set of power level modulation modes including a high power modulation mode, a medium power modulation mode, a medium power average power tracking modulation modes, and a low power average power tracking modulation mode. In other embodiments, the medium power average power tracking modulation modes are omitted.
As a further example, in a slow tracking mode of operation, the power management system 870 may disable the switch mode power supply converter 872, and configure the parallel amplifier circuit 874 to track an envelope of a modulated radio frequency input signal to be transmitted by the radio frequency power amplifier 869 as a function of a slowly modulated or unmodulated differential VRAMP signal. In the no tracking mode of operation, the power management system 870 may further configure the parallel amplifier circuit 874 to provide a modulated power supply voltage, VCC, based on a substantially unmodulated differential VRAMP signal. In the no tracking mode, the power management system 870 may be configured to generate a modulated power supply voltage, VCC that has a substantially fixed voltage level. In the slow tracking mode of operation, the parallel amplifier circuit 874 may be configured to slowly track the envelope of the differential VRAMP signal.
To minimize energy consumed from the battery during a data transmission, the power management system 870 may enable and disable various elements and signal processing functions of the switch mode power supply converter 872 and the parallel amplifier circuit 874 as a function of the power level modulation mode of operation. In some embodiments, the power management system 870 may disable the least energy efficient element and signal processing functions as a function of the expected output power to be generated by the radio frequency power amplifier 869. For example, the power management system 870 may disable portions of the switch mode power supply converter 872, the parallel amplifier circuit 874, and/or a combination thereof as the expected output power of the radio frequency power amplifier 869 decreases to achieve an overall decrease in energy consumption from the battery 20 during a data transmission. In addition, some embodiments of the power management system 870 may generate the modulated power supply output 876 using a less energy efficient device or power generation circuit in response to an expected output power of the radio frequency power amplifier 869 falling below a low power modulation mode threshold in order to disable other energy consuming circuitry and achieve an overall reduction in energy drawn from the battery 20 during a data transmission.
As a non-limiting example, in some embodiments of the high power level modulation mode and the medium power modulation mode, the power management system 870 may configure the switch mode power supply converter 872 and the parallel amplifier circuit 874 to generate the modulated power supply voltage, VCC, based on the differential VRAMP signal as a function of the expected output power to be generated by the radio frequency power amplifier 869 during the data transmission. As an example, in some embodiments of the high power modulation mode and the medium power modulation mode, the parallel amplifier circuit 874 may be configured to govern the operation of the switch mode power supply converter 872, regulate generation of the modulated power supply voltage, VCC, as a function of the differential VRAMP signal, and regulate the offset voltage, VOFFSET, across the coupling capacitor 18A. In one embodiment of the switch mode power supply converter 872, during the high power modulation mode, the switch mode power supply converter 872 boosts the power amplifier supply voltage, VCC, above the battery voltage, VBAT.
In general, in one embodiment of the pseudo-envelope tracking modulated power supply system 868, during the high power modulation mode and the medium power modulation mode, the power amplifier supply voltage, VCC, is modulated and provides envelope tracking. Further, during the low power average power tracking mode, the power amplifier supply voltage, VCC, is not modulated and provides average power tracking. In this regard, during the low power average power tracking mode, a magnitude of the power amplifier supply voltage, VCC, is adjustable based on an expected output power from the radio frequency power amplifier 869.
As an example, the parallel amplifier circuit 874 may be configured to apply a parallel amplifier circuit output current, OPAWA—OUT, from the parallel amplifier circuit 874 to regulate the modulated power supply voltage, VCC, as a function of the differential VRAMP signal. The parallel amplifier circuit 874 may provide the switch mode power supply feedback signal 40A and a threshold offset current 42, ITHRESHOLD—OFFSET, to govern the operation of the switch mode power supply converter 872 and regulate the offset voltage, VOFFSET, across the coupling capacitor 18A. In response to the switch mode power supply feedback signal 40A and the threshold offset current 42, ITHRESHOLD—OFFSET, and the differential VRAMP signal, the switch mode power supply converter 872 may generate the switching voltage, VSW, at the switching voltage output 26, and provide a delayed ICOR estimated switching voltage output 38C, VSW—EST—DELAY—ICOR, to the parallel amplifier circuit 874. In addition, the parallel amplifier circuit 874 may configure the first linear regulator output 874B, LDO1 OUTPUT, to provide a high impedance path to ground. Depending on the battery voltage, VBAT, the parallel amplifier circuit 874 may configure the second linear regulator output 874D, LDO2 OUTPUT, to provide the second linear regulator output voltage, VLDO2, at least equal to the minimum CMOS logic supply voltage to the CMOS logic supply input 869C of the radio frequency power amplifier 869.
As another non-limiting example, in some embodiments of the low power modulation mode, the power management system 870 may disable the switch mode power supply converter 872 and configure the switching voltage output 26 to provide a high impedance path to ground. In addition, the parallel amplifier circuit output 874A may be configured to provide a low impedance path to ground to short the negative terminal of the coupling capacitor 18A to ground.
To generate the modulated power supply voltage, VCC, the first linear regulator output 874B, LDO1 OUTPUT, may be configured to apply a linear regulator output current, ILDO, to the modulated power supply output 876 as a function of the differential VRAMP signal and a selected tracking mode of operation. The differential VRAMP signal may be substantially constant or only slowly modulated during the data transmission. In the case where the differential VRAMP signal is substantially constant, the power management system 870 may configure the parallel amplifier circuit 874 to operate in a no tracking mode of operation. In the no tracking mode of operation, the first linear regulator output 874B, LDO1 OUTPUT, may regulate the modulated power supply voltage, VCC, to be substantially constant or unmodulated during data transmission. Alternatively, in the case where the differential VRAMP signal slowly changes relative to the envelope of the radio frequency input signal provided to the radio frequency power amplifier 869, the power management system 870 may configure the first linear regulator output 874B, LDO1 OUTPUT, to slowly track the differential VRAMP signal during the data transmission.
In some embodiments of the low power modulation mode, the parallel amplifier circuit 874 may disable the second linear regulator output 874D, LDO2 OUTPUT. In some alternative embodiments of the low power modulation mode, the parallel amplifier circuit 874 may configure the second linear regulator output 874D, LDO2 OUTPUT, to selectively output the second linear regulator output voltage, VLDO2, to the CMOS logic supply input 869C as a function of the battery voltage, VBAT.
FIG. 2B depicts a non-limiting example of the embodiments of the switch mode power supply converter 872 that may be selectively configured to operate in a number of various buck converter modes, a number of various envelope tracking modes, a number of various average power tracking modes, and/or a combination thereof as a function of an expected output power to be generated by the radio frequency power amplifier 869 depicted in FIGS. 2A and 2C. The switch mode power supply converter 872 may further include an off mode. The various embodiments of the switch mode power supply converter 872 are described with continuing reference to the various embodiments of the power management system 870, depicted in FIGS. 2A-C.
As an example, the various envelope tracking modes may include one or more envelope tracking power modes of operation including the high power modulation mode and the medium power modulation mode. As another example, the various average power tracking modes may include one or more average power tracking modes of operation including a medium power average power tracking mode and a low power average power tracking mode. In one embodiment of the pseudo-envelope tracking modulated power supply system 868, the switch mode power supply converter 872 is arranged to cooperatively operate with the parallel amplifier circuit 874 to form the power management system 870, which operates in one of the high power modulation mode, the medium power modulation mode, and the low power average power tracking mode. In an alternate embodiment of the power management system 870, the power management system 870 operates in one of the high power modulation mode, the medium power modulation mode, the medium power average power tracking mode, and the low power average power tracking mode. The power management system 870 provides envelope tracking using the power amplifier supply voltage, VCC, during the high power modulation mode and the medium power modulation mode. As such, during the high power modulation mode and the medium power modulation mode, the power management system 870 controls the power amplifier supply voltage, VCC, to the linear radio frequency power amplifier 22 to provide the envelope tracking. Further, the pseudo-envelope tracking modulated power supply system 868 provides average power tracking during the low power average power tracking mode. As such, during the low power average power tracking mode, the power management system 870 controls the power amplifier supply voltage, VCC, to the linear radio frequency power amplifier 22 to provide the average power tracking.
In one embodiment of the pseudo-envelope tracking modulated power supply system 868, the linear radio frequency power amplifier 22 sequentially transmits multiple communications slots. As such, selection of the one of the high power modulation mode, the medium power modulation mode, and the low power average power tracking mode is based on an expected output power from the radio frequency power amplifier 869 and is made on a communications slot to communications slot basis. In one embodiment of the pseudo-envelope tracking modulated power supply system 868, during the low power average power tracking mode, adjustment of a magnitude of the power amplifier supply voltage, VCC, is made on a communications slot to communications slot basis.
The controller 50 may configure the switch mode power supply converter 872 to operate in the medium power average power tracking mode when the power management system 870 is configured to operate in a medium power average power tracking modulation mode. The controller 50 may configure the switch mode power supply converter 872 to be in a high power modulation mode when the power management system 870 is configured to operate in the high power modulation mode. The controller 50 may configure the switch mode power supply converter 872 to be in a medium power modulation mode when the power management system 870 is configured to operate in the medium power modulation mode. The controller 50 may configure the switch mode power supply converter 872 to be in an off mode when the power management system 870 is configured to operate in either a low power modulation mode or a low power average power tracking mode.
The switch mode power supply converter 872 may include embodiments of a switcher control circuit 880, a multi-level charge pump 882, a switching circuit 884, and an average frequency control circuit 885. The switcher control circuit 880, the multi-level charge pump 882, the switching circuit 884, and a feedback delay compensation circuit 852 may be configured to receive the battery voltage, VBAT. Some embodiments of the switch mode power supply converter 872 may further include the feedback delay compensation circuit 852. The controller 50 may configure the switcher control circuit 880 to govern the operation of the multi-level charge pump 882 and the switching circuit 884 as a function of the power level modulation mode and the expected output power to be generated by the embodiments of the radio frequency power amplifier 869 in response to a modulated radio frequency input signal to be transmitted. In some embodiments, the switcher control circuit 880 may also be configured to control the operation of the feedback delay compensation circuit 852 as a function of the power level modulation mode and the expected output power of the radio frequency power amplifier 869. In addition, in some embodiments, the feedback delay compensation circuit 852 may generate a feedback delay compensation signal 854, IFEEDBACK—TC, as a function of the power level modulation mode and the expected output power of the radio frequency power amplifier 869.
As a non-limiting example, in the high power modulation mode, the controller 50 or the switcher control circuit 880 may configure the feedback delay compensation circuit 852 to operate as a function of a high power mode apparent gain to increase the aggressiveness of the feedback compensation provided by the feedback delay compensation signal 854, IFEEDBACK—TC. As the apparent gain of the feedback delay compensation circuit 852 is increased, the switch mode power supply converter 872 may respond to a change in the target voltage for the modulated power supply voltage, VCC, provided by the differential VRAMP signal, which may increase the power efficiency of the various embodiments of a parallel amplifier 928, depicted in FIG. 2C.
In the medium power modulation mode, the controller 50 or the switcher control circuit 880 may configure the feedback delay compensation circuit 852 to operate as a function of a medium power mode apparent gain to decrease the aggressiveness of the feedback compensation provided by the feedback delay compensation signal 854, IFEEDBACK—TC, in order to prevent the switcher control circuit 880 from pre-maturely changing the switching voltage, VSW. The feedback delay compensation circuit 852 may operate in an overly aggressive manner when the apparent gain is set too high with respect to the expected output power to be generated by the radio frequency power amplifier 869 during a data transmission. Over aggressiveness of feedback compensation provided by the feedback delay compensation circuit 852 may result in pre-mature changes in the switching voltage, VSW, because the switch mode power supply converter 872 may overreact to a change in the target voltage for the modulated power supply voltage, VCC, provided by the differential VRAMP signal. As a result, the switch mode power supply converter 872 may generate a switching voltage that provides too much or too little energy to the modulated power supply voltage VCC, which may decrease the power efficiency of the various embodiments of the parallel amplifier 928, depicted in FIG. 2C.
In some embodiments of the medium power modulation mode, the controller 50 may set the apparent gain of the feedback delay compensation circuit 852 based on a sliding scale as a function of the expected output power to be generated by the radio frequency power amplifier 869 during the data transmission. As an alternative example, some embodiments of the switcher control circuit 880 may be further configured to adjust the apparent gain of the feedback delay compensation circuit 852 based on a segmentation mode of the switching circuit 884. In some embodiments, the controller 50 or the switcher control circuit 880 may disable the feedback delay compensation circuit 852 during the low power average power tracking mode and during the off mode. Some embodiments of the power management system 870 may enable the feedback delay compensation circuit 852 in a high power modulation mode and a medium power modulation mode.
In the low power average power tracking mode, the switcher control circuit 880 may disable the multi-level charge pump 882 and the switching circuit 884, and configure the switching voltage output 26 to provide a high impedance path to ground. In the low power average power tracking mode, the switch mode power supply converter 872 may be configured to disable a clocking signal that may be used by a μC charge pump circuit 262.
In a buck converter “bang-bang” mode of operation, the switcher control circuit 880 may disable the multi-level charge pump 882, and control the switching circuit 884 to swing the switching voltage, VSW, between the battery voltage, VBAT, and ground. In the multi-level charge pump buck converter mode, the switcher control circuit 880 may enable both the multi-level charge pump 882 and the switching circuit 884. The switcher control circuit 880 may further control the multi-level charge pump 882 and the switching circuit 884 to generate both buck level voltages and boost level voltages to provide the switching voltage, VSW, at the switching voltage output 26 as a function of the operational state of the switcher control circuit 880 and the power level modulation mode.
In a medium power average power tracking mode of operation, the switcher control circuit 880 may be configured to operate in a number of average power tracking “bang-bang” modes of operation. As an example, in some embodiments of an average power tracking “bang-bang” mode of operation, the switcher control circuit 880 may configure the multi-level charge pump 882 and the switching circuit 884 to switch the switching voltage, VSW, between only a first bang-bang switching voltage, VSW—BB1, and a second bang-bang switching voltage, VSW—BB2, during a data transmission, where the first bang-bang switching voltage, VSW—BB1, is less than the second bang-bang switching voltage, VSW—BB2.
Unlike a buck converter mode of operation in which the switching voltage VSW swings between ground and the battery supply, VBAT, the first bang-bang switching voltage, VSW—BB1, may be substantially equal to ground, the battery voltage, VBAT, or the switching voltage VSW between ground and the battery voltage, VBAT. The second bang-bang switching voltage, VSW—BB2, may be substantially equal to the supply voltage, VBAT, or a charge pump output voltage generated by the multi-level charge pump 882 from the battery voltage, VBAT. The average power tracking “bang-bang” modes of operation may include an average power tracking “buck-buck” mode of operation and an average power tracking “buck-boost” mode of operation.
In the average power tracking “buck-buck” mode of operation, the switcher control circuit 880 may configure the multi-level charge pump 882 and the switching circuit 884 to generate a first bang-bang switching voltage, VSW—BB1, and a second bang-bang switching voltage, VSW—BB2, that are no greater than the battery voltage, VBAT. For example, the switcher control circuit 880 may configure the multi-level charge pump 882 to generate only a bucked output voltage at a charge pump output 64. As an example, the switcher control circuit may configure the multi-level charge pump 882 to generate a first buck mode output voltage, VFIRST—BUCK, substantially equal to 1/2×VBAT in a first buck mode of operation. In the average power tracking “buck-buck” mode, the switcher control circuit 880 may disable the multi-level charge pump 882 provided the first bang-bang switching voltage, VSW—BB1, and the second bang-bang switching voltage, VSW—BB2, are a shunt mode output voltage substantially equal to ground and a series mode output voltage substantially equal to VBAT, respectively.
In the average power tracking “buck-boost” mode, the first bang-bang switching voltage, VSW—BB1, may be no greater than the battery voltage, VBAT, and the second bang-bang switching voltage, VSW—BB2, is a boost voltage that is greater than the battery voltage, VBAT. In the average power tracking “buck-boost” mode, the switcher control circuit 880 may configure the multi-level charge pump 882 and the switching circuit 884 to generate the first bang-bang switching voltage, VSW—BB1. The switcher control circuit 880 may configure the multi-level charge pump 882 to generate the second bang-bang switching voltage, VSW—BB2. A further description of the average power tracking “bang-bang” modes of operation is provided below.
Some embodiments of the switcher control circuit 880 may be configured to form a composite control signal as a function of the various envelope tracking modes, the various average power tracking modes, and buck converter modes. As an example, the various embodiments of the switcher control circuit 880 may combine the various fractional amounts and combinations of the feedback delay compensation signal 854, IFEEDBACK—TC, the switch mode power supply feedback signal 40A, and the threshold offset current 42, ITHRESHOLD—OFFSET, to form one or more composite control signals as a function of the power level modulation mode. In some embodiments, the composite control signal may depend on the power level modulation mode.
As an example, FIG. 2C depicts an embodiment of the power management system 870 in which a parallel amplifier 928 may generate the switch mode power supply feedback signal 40A in the high power modulation mode and medium power modulation mode. In addition, a VOFFSET loop circuit 41 may generate the threshold offset current 42, ITHRESHOLD—OFFSET, in the high power modulation mode and the medium power modulation mode.
Returning to FIG. 2B, the switcher control circuit 880 may also provide a series switch control signal 66 and a shunt switch control signal 68 to the switching circuit 884. In response to an assertion of the series switch control signal 66, the switching circuit 884 couples the switching voltage output 26 to the battery voltage, VBAT, to generate the switching voltage, VSW, substantially equal to VBAT. In response to the shunt switch control signal 68, the switching circuit 884 couples the switching voltage output 26 to ground to generate the switching voltage, VSW, substantially equal to zero. In addition, the switcher control circuit 880 provides a segmentation control signal 880A to the switching circuit 884 as a function of the power level modulation mode. In some embodiments, the switcher control circuit 880 may generate the segmentation control signal 880A as a function of the power level modulation mode and the expected output power to be generated by the radio frequency power amplifier 869 during a data transmission. For example, some embodiments of the power management system 870 may be configured to generate the segmentation control signal 880A based on an average expected output power, POUT—AVE, of the radio frequency power amplifier 869 that maximizes the efficiency of the switch mode power supply converter 872.
In general, the switch mode power supply converter 872 has a segmented output stage, such that during the high power modulation mode and the medium power modulation mode, segment selection of the segmented output stage is based on an expected output power from the radio frequency power amplifier 869 to increase efficiency of the pseudo-envelope tracking modulated power supply system 868.
The switcher control circuit 880 may configure the switch mode power supply converter 872 to generate a switching voltage, VSW, at the switching voltage output 26 based on an operational state of the switcher control circuit 880 as a function of a power level modulation mode, which is dependent on the expected output power to be generated by the radio frequency power amplifier 869 during a data transmission. In some embodiments, the switcher control circuit 880 may configure the multi-level charge pump 882 and the switching circuit 884 to operate in one of a buck converter “bang-bang” mode, a multi-level charge pump buck converter mode, and an average power tracking mode of operation as a function of the power level modulation mode and operational mode of the switcher control circuit 880.
Referring to FIGS. 2C and 2B, in some embodiments, a control signal 926, received at the non-inverting input of the parallel amplifier 928 to generate the parallel amplifier output current, IPARA—AMP, may be generated by a differential filter 924 as a function of the power level modulation mode. For example, in the high power modulation mode, the differential filter 924 may provide an increased level of frequency compensation or correction as compared to the frequency compensation or correction provided by the differential filter 924 in the medium power modulation mode. Accordingly, some embodiments of the switcher control circuit 880, the switch mode power supply converter 872, the parallel amplifier circuit 874 and/or a combination thereof, may be further adapted to adjust a scaling factor, M, provided to a buffer scalar 434, and/or the magnitude of the delayed ICOR estimated switching voltage output 38C, VSW—EST—DELAY—ICOR, as a function of the power level modulation mode.
Some alternative embodiments of the switcher control circuit 880, the switch mode power supply converter 872, the parallel amplifier circuit 874, and/or combinations thereof, may be further configured to adjust the magnitude of the delayed ICOR estimated switching voltage output 38C, VSW—EST—DELAY—ICOR, based on the magnitude of the control signal 926 that is received by at the non-inverting input of the parallel amplifier 928, which is generated by the differential filter 924. In some embodiments, the switcher control circuit 880 may selectively adjust the scaling factor, M, as a function of the magnitude of the differential VRAMP signal and the power level modulation mode. For example, in some embodiments of the switcher control circuit 880, the scaling factor, M, may be further adjusted as a function of the power level modulation mode to reflect the amount of frequency compensation or correction applied by the differential filter 924 to generate the control signal 926 received at the non-inverting input 928A of the parallel amplifier 928, depicted in FIG. 2C.
In some embodiments of the power management system 870, either the switch mode power supply converter 872 or the parallel amplifier circuit 874 may be further adapted to adjust the scaling factor, M, based on the magnitude of the control signal 926 or the power level modulation mode. For example, in some embodiments, the magnitude of the delayed ICOR estimated switching voltage output 38C, VSW—EST—DELAY—ICOR, may be adjusted as a function of the power level modulation mode, the magnitude of the differential VRAMP signal, and the expected frequency response of the parallel amplifier 928 when operating in each of the respective power level modulation modes.
For example, a switcher propagation delay is a time period between when the state of the switcher control circuit 880 changes to a new operational state and the switching voltage, VSW, generated in response to the new operational state of the switcher control circuit 880, is generated at the switching voltage output 26. In some embodiments of the switch mode power supply converter 872, the switcher propagation delay may vary based on being configured to operate in the envelope tracking mode of operation and the average power tracking mode. Thus, the controller 50 may be configured to adjust the programmable delay period as a function of an expected output power to be generated by the radio frequency power.
As another example, in some embodiments, the switching circuit 884 may be a segmented switching circuit having a number of sets of series switch and shunt switch pairs. The sets of series switch and shunt switch pairs may be arranged in parallel and operably coupled to form a segmented series switch and shunt switch network. The switcher control circuit 880 may generate a series switch control signal 66, a shunt switch control signal 68, and the segmentation control signal 880A based on an operational state of the switcher control circuit 880 to control the operation of the switching circuit 884. In addition, the segmentation control signal 880A may be dependent on the power level modulation mode of the power management system 870. For example, the switcher control circuit 880 may configure the segmentation control signal 880A to enable or disable various combinations of the sets of series switch and shunt switch pairs of the switching circuit 884 based on the power level modulation mode of operation of the respective power management system 870, depicted in FIG. 2A-C. As an example, in some embodiments of the medium power modulation mode, the switcher control circuit 880 may generate a segmentation control signal 880A to enable either 75% or 50% of the number of sets of series switch and shunt switch pairs of the switching circuit 884.
In some embodiments of the switching circuit 884, the switcher propagation delay may vary depending on the number of sets of series switch and shunt switch pairs configured to operate during a data transmission. In some embodiments, the switcher control circuit 880 may be configured to adjust a programmable delay period depending on the segmentation control signal 880A to maintain the temporal alignment of the delayed ICOR estimated switching voltage output 38C VSW—EST—DELAY—ICOR with respect to the switching voltage, VSW, provided at the switching voltage output 26.
The switching circuit 884 may include a segmentation control circuit 886 configured to receive a segmentation control signal 880A from the switcher control circuit 880. The switching circuit 884 may further include segmented series switches 888 and segmented shunt switches 890 in communication with the segmentation control circuit 886. The segmented series switches 888 may include a first series switch 892, a second series switch 894, a third series switch 896, and a fourth series switch 898. The segmented shunt switches 890 may include a first shunt switch 900, a second shunt switch 902, a third shunt switch 904, and a fourth shunt switch 906.
A source 892S of the first series switch 892, a source 894S of the second series switch 894, a source 896S of the third series switch 896, and a source 898S of the fourth series switch 898 are in communication with a supply voltage received from the battery 20 substantially equal to the battery voltage, VBAT. A drain 892D of the first series switch 892, a drain 894D of the second series switch 894, a drain 896D of the third series switch 896, and a drain 898D of the fourth series switch 898 are respectively coupled to a drain 900D of the first shunt switch 900, a drain 902D of the second shunt switch 902, a drain 904D of the third shunt switch 904, and a drain 906D of the fourth shunt switch 906 to form the switching voltage output 26. A source 900S of the first shunt switch 900, a source 902S of the second shunt switch 902, a source 904S of the third shunt switch 904, and a source 906S of the fourth shunt switch 906 are in communication with a reference voltage substantially equal to ground.
The segmentation control circuit 886 may include a first series switch control output 908 coupled to the gate 892G of the first series switch 892, a first shunt switch control output 910 coupled to the gate 900G of the first shunt switch 900, a second series switch control output 912 coupled to the gate 894G of the second series switch 894, a second shunt switch control output 914 coupled to the gate 902G of the second shunt switch 902, a third series switch control output 916 coupled to the gate 896G of the third series switch 896, a third shunt control output 918 coupled to the gate 904G of the third shunt switch 904, a fourth series switch control output 920 couple to the gate 898G of the fourth series switch 898, and a fourth shunt switch control output 922 coupled to the gate 906G of the fourth shunt switch 906.
Operationally, the segmentation control circuit 886 may divide the segmented series switches 888 and segmented shunt switches 890 into logical groupings of sets of series and shunt switches such that each set of series and shunt switches includes one of the segmented series switches 888 and one of the segmented shunt switches 890. For example, a first set of series and shunt switches may include the first series switch 892 and the first shunt switch 900. A second set of series and shunt switches may include the second series switch 894 and the second shunt switch 902. A third set of series and shunt switches may include the third series switch 896 and the third shunt switch 904. A fourth set of series and shunt switches may include the fourth series switch 898 and the fourth shunt switch 906.
The segmentation control circuit 886 is configured to receive a series switch control signal 66 and a shunt switch control signal 68 from the switcher control circuit 880. The power management system 870 may configure the switcher control circuit 880 to generate a segmentation control signal 880A to select which of the segmented series switches 888 and segmented shunt switches 890 are to be enabled by the segmentation control circuit 886 to generate the switching voltage, VSW, at the switching voltage output 26 as a function of the average expected output power, POUT—AVE, to be generated by the radio frequency power amplifier 869 during the data transmission. Illustratively, in the case where there are four sets of series and shunt switches, the operation of the segmentation control circuit 886 may be divided into four regions or modes of operation.
In some embodiments, the switcher control circuit 880 may generate the segmentation control signal 880A as a function of the average expected output power, POUT—AVE, and a set of switcher output power thresholds including a first switcher output power threshold, POUT1, a second switcher output power threshold, POUT2, and a third switcher output power threshold, POUT3. The values of the first switcher output power threshold, POUT1, the second switcher output power threshold, POUT2, and the third switcher output power threshold, POUT3, may be determined to maximize the efficiency of the switch mode power supply converter 872 with respect to the expected output power of the radio frequency power amplifier 869 as a function of the power level modulation mode and an expected load line, RRF—AMP—EXP, of the radio frequency power amplifier 869 during the data transmission.
In the case where the average expected output power, POUT—AVE, of the radio frequency power amplifier 869 is at least equal to the first switcher output power threshold, POUT1, the segmentation control signal 880A may configure the segmentation control circuit 886 to enable all four of the series switch and shunt switch segments. In the case where the average expected output power, POUT—AVE, of the radio frequency power amplifier 869 is less than the first switcher output power threshold, POUT1, and at least equal to the second switcher output power threshold, POUT2, the segmentation control signal 880A may configure the segmentation control circuit 886 to enable three of the series switch and shunt switch segments. In the case where the average expected output power, POUT—AVE, of the radio frequency power amplifier 869 is less than the second switcher output power threshold, POUT2, and at least equal to the third switcher output power threshold, POUT3, the segmentation control signal 880A may configure the segmentation control circuit 886 to enable two of the series switch and shunt switch segments. And in the case where the average expected output power, POUT—AVE, of the radio frequency power amplifier 869 is less than the third switcher output power threshold, POUT3, the segmentation control signal 880A may configure the segmentation control circuit 886 to enable one of the series switch and shunt switch segments.
The multi-level charge pump 882 may configure a multi-level charge pump switching network to generate a variety of “boost” output voltages and “buck” output voltages as a function of a charge pump mode control signal 62 received from the switcher control circuit 880. Some embodiments of the multi-level charge pump 882 may generate a variety of “boost” output voltages and “buck” output voltages as a multi-level charge pump output voltage, VMLCP, in response to the charge pump mode control input 62 generated by the switcher control circuit 880. The multi-level charge pump 882 may provide the multi-level charge pump output voltage, VMLCP, to the charge pump output 64, which may be coupled through the switching circuit 884 to the switching voltage output 26.
For example, in a second boost mode of operation, the multi-level charge pump 882 may configure the multi-level charge pump switching network to generate a second boost mode output voltage, VSECOND—BOOST, substantially equal to 2×VBAT at the charge pump output 64. In a first boost mode of operation, the multi-level charge pump 882 may configure the switching network to generate a first boost mode output voltage at the charge pump output 64 substantially equal to 3/2×VBAT. In a first buck mode of operation, the multi-level charge pump 882 may configure the multi-level charge pump switching network to generate a first buck mode output voltage at the charge pump output 64 substantially equal to 1/2×VBAT. In some alternative embodiments, the multi-level charge pump 882 may be configured to generate other ratios of boost mode output voltages and buck mode output voltage.
Some embodiments of the multi-level charge pump 882 may include only two flying capacitors that are coupled in various switching arrangements with respect to each other, the battery voltage, VBAT, and the charge pump output 64 to generate the various charge pump output voltages at the charge pump output 64. For example, similar to the μC charge pump circuit 262, some embodiments of the multi-level charge pump 882 may generate various ratios of output voltages that may be provided as a boost output voltage or a buck output voltage to the switching voltage output 26 as the switching voltage, VSW. In still other alternative embodiments, the multi-level charge pump 882 may generate a boost output voltage or a buck output voltage with respect to a supply voltage other than the battery voltage, VBAT, where the supply voltage may be greater than the battery voltage, VBAT, or less than the battery voltage, VBAT. In some alternative embodiments, the supply voltage provided to the multi-level charge pump 882 may be a boosted voltage or a bucked voltage derived from the battery voltage, VBAT.
Based on the power level modulation mode, in some embodiments of the multi-level charge pump buck converter mode of operation, the switcher control circuit 880 may configure the switch mode power supply converter 872 to generate a series output voltage substantially equal to the battery voltage, VBAT, a shunt output voltage substantially equal to a ground voltage, and a subset of the available charge pump output voltages. As an example, as a function of the power level modulation mode, the switcher control circuit 880 may configure the multi-level charge pump 882 and the switching circuit 884 to generate a shunt mode output voltage substantially equal to a ground voltage in the shunt output mode, a series mode output voltage substantially equal to VBAT in the series output mode, and a first boost mode output voltage VFIRST—BOOST substantially equal to 3/2×VBAT in the first boost output mode. As another non-limiting example, as a function of the power level modulation mode, in some power level modulation modes, the switcher control circuit 880 may configure the multi-level charge pump 882 to provide a first buck mode output voltage substantially equal to 1/2×VBAT in the first buck mode of operation. As an example, as a function of the power level modulation mode, the switcher control circuit 880 may configure the multi-level charge pump 882 and the switching circuit 884 to generate a shunt mode output voltage substantially equal to ground, a first buck mode output voltage substantially equal to 1/2×VBAT, a series mode output voltage substantially equal to VBAT, and a first boost mode output voltage substantially equal to 3/2×VBAT as a function of the operational state of the switcher control circuit 880. As still another non-limiting example, in some power level modulation modes, the switcher control circuit 880 may configure the multi-level charge pump 882 to only operate in a first boost mode of operation to generate a first boost mode output voltage, VFIRST—BOOST, substantially equal to 3/2×VBAT.
As another example, in some power level modulation modes, the multi-level charge pump 882 may be configured to only operate in the second boost mode of operation. In still another example, in some power level modulation modes, the multi-level charge pump 882 may be configured to operate in the first buck mode and either the first boost mode or the second boost mode of operation. For example, in some power level modulation modes, the switcher control circuit 880 may configure the multi-level charge pump 882 to provide either a first buck mode output voltage substantially equal to 1/2×VBAT and a first boost mode output voltage substantially equal to 3/2×VBAT as a function of the operational state of the switcher control circuit 880. In other power level modulation modes, the switcher control circuit may configure the multi-level charge pump 882 to provide a buck output voltage substantially equal to 1/2×VBAT in the first buck mode and a second boost level output voltage substantially equal to 2×VBAT as a function of the operational state of the switcher control circuit 880.
Depending on a power level modulation mode, a characteristic of the data transmission, and/or a desired distribution of harmonics of the switching frequency within the frequency spectrum, the controller 50 may configure the comparator thresholds to set the equivalent main ripple voltage level at the modulated power supply output 876 and/or the switching frequency of the switch mode power supply converter 872. For example, in the medium power average power tracking modulation mode
The parallel amplifier 928 may include a non-inverting input 928A configured to receive the control signal 926. In some embodiments, the control signal 926 may be a compensated VRAMP signal, VRAMP—C. The parallel amplifier 928 may also include an inverting input 928B in communication with the modulated power supply output 876. Based on the difference between the control signal and the modulated power supply voltage, VCC, the parallel amplifier 928 may generate a parallel amplifier output current, IPARA—AMP, at the parallel amplifier output 928C in order to generate the parallel amplifier output voltage, VPARA—AMP at the parallel amplifier circuit output 874A during the high power modulation mode and the medium power modulation mode. Additionally, the parallel amplifier 928 may be disabled during the low power average power tracking mode. In another embodiment of the parallel amplifier 928, the parallel amplifier 928 is disabled during the medium power average power tracking mode.
The parallel amplifier 928 may generate a scaled parallel amplifier output current estimate, IPARA—AMP—SENSE, which is a fractional representation of the parallel amplifier output current, IPARA—AMP, from the parallel amplifier feedback output 928E. The parallel amplifier 928 may include a parallel amplifier supply voltage input 928D configured to receive a μC charge pump output voltage, VμC—OUT, from the μC charge pump circuit 262, such that the parallel amplifier output voltage, VPARA—AMP is based on the μC charge pump output voltage, VμC—OUT during the high power modulation mode and the medium power modulation mode. In general, the power amplifier supply voltage, VCC, is based on the μC charge pump output voltage, VμC—OUT, during the high power modulation mode and the medium power modulation mode.
In one embodiment of the parallel amplifier 928, the parallel amplifier 928 has a segmented output stage, such that during the high power modulation mode and the medium power modulation mode, segment selection of the segmented output stage is based on an expected output power from the radio frequency power amplifier 869 to increase efficiency of the pseudo-envelope tracking modulated power supply system 868.
Alternatively, as previously described, in some embodiments the parallel amplifier supply voltage input 928D may be switchably configured to be powered by the μC charge pump output voltage, VμC—OUT, or a supply voltage provided by the multi-level charge pump 882 of the switch mode power supply converter 872, depicted in FIG. 2B.
For example, in some embodiments, the μC charge pump circuit 262 may generate the μC charge pump output voltage, VμC—OUT, as a function of the battery voltage and the modulation mode of operation. As such, μC the charge pump output voltage, VμC—OUT, may be based on a charge-pump-ratio, which may be based on one of at least the high power modulation mode, the medium power modulation mode, and the low power average power tracking mode. For example, in the high power modulation mode, the power management system 870 may configure the μC charge pump circuit 262 to operate in the 1×VBAT mode or the 4/3×VBAT mode to generate the μC charge pump output voltage, VμC—OUT, substantially equal to either the battery voltage, 1×VBAT, or 4/3×VBAT, respectively, which equates to a charge-pump-ratio of 1 or 4/3, respectively. In the medium power modulation mode, the power management system 870 may configure the μC charge pump circuit 262 to operate in the 1×VBAT mode or the 2/3×VBAT mode to generate the μC charge pump output voltage, VμC—OUT, substantially equal to either the battery voltage, VBAT, or 2/3×VBAT, respectively, which equates to a charge-pump-ratio of 1 or 2/3, respectively. In some embodiments, in the low power modulation mode, the power management system 870 may configure the μC charge pump circuit 262 to operate in the 1/433 VBAT mode, 1/3×VBAT mode, or the 1/2×VBAT mode to generate the μC charge pump output voltage, VμC—OUT, substantially equal to 1/4×VBAT, 1/3×VBAT, or 1/2×VBAT, respectively, which equates to a charge-pump-ratio of 1/4, 1/3, or 1/2, respectively.
In one embodiment of the μC charge pump circuit 262, the μC charge pump circuit 262 provides the μC charge pump output voltage, VμC—OUT based on the battery voltage, VBAT. In one embodiment of the μC charge pump circuit 262, the μC charge pump circuit 262 is a capacitor-based charge pump circuit 262, such that multiple switched flying capacitors are used to provide the μC charge pump output voltage, VμC—OUT. In an alternate embodiment of the parallel amplifier circuit 874, the μC charge pump circuit 262 is replaced with a μL charge pump circuit (not shown), which provides the μC charge pump output voltage, VμC—OUT based on the battery voltage, VBAT. The μL charge pump circuit (not shown) is an inductor-based charge pump circuit, such that at least one inductor is used to provide the μC charge pump output voltage, VμC—OUT. As such, either the μC charge pump circuit 262, the μL charge pump circuit (not shown), or both may operate in a boost, a buck mode, or both. As such, the μC charge pump output voltage, VμC—OUT may be greater than, equal to, or less than the battery voltage, VBAT.
In one embodiment of the μC charge pump circuit 262, the μC charge pump circuit 262 has a segmented output stage, such that during the high power modulation mode, during the medium power modulation mode, and during the low power average power tracking mode, segment selection of the segmented output stage is based on an expected output power from the radio frequency power amplifier 869 to increase efficiency of the pseudo-envelope tracking modulated power supply system 868.
In some embodiments, a segmented parallel amplifier output stage of the parallel amplifier 928 may be configured based upon the expected output power of the radio frequency power amplifier 869. As an example, the segmentation configuration of the parallel amplifier 928 may be a function of a maximum instantaneous output power, PINST—MAX, to be generated by the radio frequency power amplifier 869 during the data transmission and the expected load line, RRF—AMP—EXP, of the radio frequency power amplifier 869 during the data transmission. As an example, in some embodiments, a maximum instantaneous output current, IMAX—PARA—AMP, to be provided by the parallel amplifier 928 during the data transmission may be substantially equal to (PINST—MAX/RRF—AMP—EXP)1/2. In some embodiments, the parallel amplifier 928 may include a maximum parallel amplifier output current, IPARA—MAX, which is the maximum output current to be generated by the parallel amplifier 928. In some embodiments, the power management system 870 may configure the segmentation configuration of the parallel amplifier 928 based on the maximum parallel amplifier output current, IPARA—MAX, and the maximum instantaneous output current, IMAX—PARA—AMP.
For example, in some embodiments, the controller may determine the maximum instantaneous output current, IMAX—PARA—AMP, based on the envelope characteristics of the modulated radio frequency input signal to be transmitted and the expected load line, RRF—AMP—EXP, of the radio frequency power amplifier 869 during the data transmission. The power management system 870 may determine the maximum instantaneous output power, PINST—MAX, based on the envelope characteristics of the modulated radio frequency input signal. Based on the maximum instantaneous output current, IMAX—PARA—AMP, the power management system 870 may determine an estimated percentage of output current generation capacity of the parallel amplifier 928 that may be used during the data transmission.
For example, the power management system 870 may calculate the percentage of the output current generation capacity based on the ratio of the maximum instantaneous output current, IMAX—PARA—AMP, to the maximum parallel amplifier output current, IPARA—MAX. The power management system 870 may determine the number of output stage segments of the parallel amplifier 928 to enable based on the estimated percentage of output current generation capacity of the parallel amplifier 928 to be used. For example, in the case where the parallel amplifier 928 includes two output stage segments that are configured to have a substantially equal output current generation capacity, the power management system 870 may set the segmentation configuration to be 100% when the ratio of the maximum instantaneous output current, IMAX—PARA—AMP, to the maximum parallel amplifier output current, IPARA—MAX, is substantially equal to or near at least 50%. The power management system 870 may set the segmentation configuration to be 50% when the ratio of the maximum instantaneous output current, IMAX—PARA—AMP, to the maximum parallel amplifier output current, IPARA—MAX, is at least less than 50%. In the case where the output stage segments of the parallel amplifier 928 are not substantially equal, the controller 50 may determine which of the output stage segments to enable based on the ratio of the maximum instantaneous output current, IMAX—PARA—AMP, and the current generation capacity of each of the output stage segments.
In some alternative embodiments, the segmentation configuration of the parallel amplifier 928 may be based on the expected peak-to-peak swing of a modulated power supply voltage, VCC—PKPK, and the expected load line, RRF—AMP—EXP, of the radio frequency power amplifier 869 during the data transmission.
For example, when operating in the high power modulation mode, the power management system 870 may set the segmentation configuration to be 100%. Alternatively, the power management system 870 may configure the parallel amplifier 928 to use only the first output stage segment or only the second output stage segment while operating in the medium power modulation mode depending on the ratio of the maximum instantaneous output current, IMAX—PARA—AMP, to the maximum parallel amplifier output current, IPARA—MAX. And in the low power modulation mode, the power management system 870 may disable the parallel amplifier 928 to place the parallel amplifier output 928C in a high impedance mode.
As previously described with respect to FIG. 2A, FIG. 2C depicts that the parallel amplifier circuit 874 may provide the threshold offset current 42, ITHRESHOLD—OFFSET, from an embodiment of the VOFFSET loop circuit 41 to regulate the offset voltage, VOFFSET, across the coupling capacitor 18A.
In some embodiments, the VOFFSET loop circuit 41 may be configured to generate the threshold offset current 42, ITHRESHOLD—OFFSET, that represents an average or integrated error between the modulated power supply voltage, VCC, and a VRAMP signal when the switch mode power supply converter 872 is configured to operate in an average power tracking mode of operation. Some embodiments of the VOFFSET loop circuit 41 may be configured to pre-charge the bypass capacitor 19 and the coupling capacitor 18A while the switch mode power supply converter 872 is configured to operate in the average power tracking mode of operation.
The parallel amplifier circuit 874 may further include a linear regulator 930, LDO. The linear regulator 930, LDO, may be a low dropout voltage linear regulator. The parallel amplifier circuit 874 may also include a parallel amplifier output bypass switch 936, a linear regulator output selection switch 938, and a feedback selection switch 940. The parallel amplifier output bypass switch 936 includes a first terminal 936A coupled to the parallel amplifier output 928C and a second terminal 936B coupled to ground. The power management system 870 may configure the parallel amplifier output bypass switch 936 to close when the parallel amplifier 928 is disabled.
For example, the power management system 870 may configure the parallel amplifier output bypass switch 936 to close based on a determination that the expected output power of the radio frequency power amplifier 869 is less than the low power modulation mode threshold or the parallel amplifier output 928C is disabled and configured to provide a high impedance. Alternatively, the power management system 870 may configure the parallel amplifier output bypass switch 936 to be open when the parallel amplifier 928 is enabled. As such, the parallel amplifier output bypass switch 936 is coupled between the parallel amplifier circuit output 874A and ground. During the high power modulation mode and the medium power modulation mode, the parallel amplifier output bypass switch 936 is OPEN and during the low power average power tracking mode, the parallel amplifier output bypass switch 936 is CLOSED.
The linear regulator output selection switch 938 may include an input terminal 938A coupled to a linear regulator output 930C of the linear regulator 930, LDO, a first output terminal 938B in communication with the modulated power supply output 876, and a second output terminal 938C in communication with the second linear regulator output 874D, LDO2 OUTPUT, in communication with the CMOS logic supply input 869C of the radio frequency power amplifier 869. In one embodiment of the 780, the μC charge pump circuit 262 provides the second linear regulator output voltage, VLDO2, to PA CMOS bias circuitry in the radio frequency power amplifier 869 via the linear regulator 930, LDO.
The feedback selection switch 940 includes an output terminal 940A in communication with an inverting input 930B of the linear regulator 930, LDO, a first input terminal 940B in communication with the modulated power supply output 876, and a second input terminal 940C in communication with the second linear regulator output 874D, LDO2 OUTPUT, of the parallel amplifier circuit 874. The linear regulator 930, LDO, also includes a linear regulator power supply input 930D configured to receive the μC charge pump output voltage, VμC—OUT. The μC charge pump output voltage, VμC—OUT, may be configured provide a voltage level to the linear regulator power supply input 930D as a function of the battery voltage, VBAT, and the expected output power of the radio frequency power amplifier 869.
The linear regulator 930, LDO, may also include a non-inverting input 930A in communication with the non-inverting input 928A of the parallel amplifier. The non-inverting input 930A of the linear regulator 930, LDO, may also be in communication with the differential filter 924, and configured to receive the control signal 926 at the non-inverting input 930A. The linear regulator 930, LDO, may also receive a linear regulator feedback signal, LDO FEEDBACK, from the output terminal 940A of the feedback selection switch 940. Based on the difference between the control signal 926 and the linear regulator feedback signal, LDO FEEDBACK, the linear regulator 930, LDO, may generate a linear regulator output voltage at the linear regulator output 930C. Based on the switch states of the linear regulator output selection switch 938 and the feedback selection switch 940, the linear regulator 930, LDO, may generate a linear regulator output voltage to apply the first linear regulator output current 878A, ILDO, to the modulated power supply output 876.
In this regard, in one embodiment of the linear regulator output selection switch 938 and the linear regulator 930, LDO, during the low power average power tracking mode, the linear regulator 930, LDO, provides the power amplifier supply voltage, VCC based on the μC charge pump output voltage, VμC—OUT. As such, the power amplifier supply voltage, VCC, is based on the μC charge pump output voltage, VμC—OUT, during the low power average power tracking mode. Further, in one embodiment of the linear regulator 930, LDO, during the medium power modulation mode, the linear regulator 930, LDO, is disabled. Additionally, in one embodiment of the linear regulator 930, LDO, during the high power modulation mode, the linear regulator 930, LDO, is disabled.
In addition, in one embodiment of the linear regulator 930, LDO, during the medium power average power tracking mode, the linear regulator 930, LDO, is disabled. In one embodiment of the linear regulator 930, LDO, and the the parallel amplifier 928, during the medium power average power tracking mode, both the linear regulator 930, LDO, and the parallel amplifier 928, are disabled. Further, in one embodiment of the switch mode power supply converter 872, during the medium power average power tracking mode, the switch mode power supply converter 872 provides the power amplifier supply voltage, VCC.
FIG. 3 depicts a method 1700 for configuring the operation of the power management system 870 (FIG. 2A). The power management system 870 may determine an expected output power to be generated by a radio frequency power amplifier 869 (FIG. 2A) during a data transmission. (Step 1702). For example, in some embodiments, the controller 50 (FIG. 2A) may determine the expected output power to be generated by the radio frequency power amplifier 869 (FIG. 2A) based upon the envelope characteristics of a data signal to be transmitted during a data transmission slot. In other embodiments, the digital baseband processing portion of the transceiver or modem that provides the differential VRAMP signal to the parallel amplifier circuit 874 (FIG. 2A) may determine the expected output power to be generated by the radio frequency power amplifier 869 (FIG. 2A).
Based on the expected output power to be generated by the radio frequency power amplifier 869 (FIG. 2A) during the data transmission, the power management system 870 (FIG. 2A) may select a power modulation mode of operation from among a number of power level modulation modes of operation. (Step 1704). For example, the power management system 870 (FIG. 2A) includes the high power modulation mode, the medium power modulation mode, and the low power average power tracking mode. As such, the power management system 870 (FIG. 2A) selects the one of the high power modulation mode, the medium power modulation mode, and the low power average power tracking mode.
In the case where the expected output power to be generated by the radio frequency power amplifier 869 (FIG. 2A) is greater than or equal to a high power modulation mode threshold, the power management system 870 (FIG. 2A) configures the power management system 870 (FIG. 2A) to operate in the high power modulation mode. (Step 1706). Alternatively, in the case where the expected output power to be generated by the radio frequency power amplifier 869 (FIG. 2A) is less than the high power modulation mode threshold but greater than or equal to a medium power modulation mode threshold, the power management system 870 (FIG. 2A) configures the power management system 870 (FIG. 2A) to operate in the medium power modulation mode. (Step 1708).
In the case where the expected output power to be generated by the radio frequency power amplifier 869 (FIG. 2A) is less than the medium power modulation mode threshold but greater than or equal to the low power modulation mode threshold, the power management system 870 (FIG. 2A) may configure the power management system 870 (FIG. 2A) to operate in the medium power average power tracking mode. (Step 1710). In the case where the expected output power to be generated by the radio frequency power amplifier 869 (FIG. 2A) is less than the low power modulation mode threshold, the power management system 870 (FIG. 2A) may configure the power management system 870 (FIG. 2A) to operate in the low power average power tracking mode. (Step 1712).
In another embodiment of the power management system 870 (FIG. 2A), in the case where the expected output power to be generated by the radio frequency power amplifier 869 (FIG. 2A) is less than the medium power modulation mode threshold, the power management system 870 (FIG. 2A) may configure the power management system 870 (FIG. 2A) to operate in the low power average power tracking mode (Step 1712).
In one embodiment of the power management system 870 (FIG. 2A), the high power modulation mode threshold is equal to about three decibels less than a maximum expected output power from the radio frequency power amplifier 869 (FIG. 2A). In one embodiment of the power management system 870 (FIG. 2A), the medium power modulation mode threshold is equal to about ten decibels less than a maximum expected output power from the radio frequency power amplifier 869 (FIG. 2A).
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.

## Claims

1. Circuitry comprising a parallel amplifier circuit and a switch mode power supply converter configured to cooperatively operate with the parallel amplifier circuit to form a power management system, which is configured to:
operate in one of at least a high power modulation mode, a medium power modulation mode, and a low power average power tracking mode;
during the high power modulation mode and the medium power modulation mode, control a power amplifier supply voltage to a radio frequency power amplifier to provide envelope tracking; and
during the low power average power tracking mode, control the power amplifier supply voltage to the radio frequency power amplifier to provide average power tracking.

2. The circuitry of claim 1 wherein the power management system is further configured to:
operate in the high power modulation mode when an expected output power from the radio frequency power amplifier is greater than a high power modulation mode threshold;
operate in the medium power modulation mode when the expected output power from the radio frequency power amplifier is greater than a medium power modulation mode threshold and is less than the high power modulation mode threshold; and
operate in the low power average power tracking mode when the expected output power from the radio frequency power amplifier is less than the medium power modulation mode threshold.

3. The circuitry of claim 2 wherein the power management system is further configured to:
operate in the high power modulation mode when the expected output power from the radio frequency power amplifier is equal to the high power modulation mode threshold; and
operate in the medium power modulation mode when the expected output power from the radio frequency power amplifier is equal to the medium power modulation mode threshold.

4. The circuitry of claim 2 wherein:
the high power modulation mode threshold is equal to about three decibels less than a maximum expected output power from the radio frequency power amplifier; and
the medium power modulation mode threshold is equal to about ten decibels less than the maximum expected output power from the radio frequency power amplifier.

5. The circuitry of claim 1 further comprising the radio frequency power amplifier, which is configured to generate an amplified modulated radio frequency output signal as a function of a modulated radio frequency input signal and the power amplifier supply voltage.

6. The circuitry of claim 1 wherein:
the power amplifier supply voltage is generated at a modulated power supply output;
the switch mode power supply converter has a switching voltage output; and
a power inductor is coupled between the switching voltage output and the modulated power supply output.

7. The circuitry of claim 6 wherein the power management system is further configured to provide a high impedance path to ground at the switching voltage output during the low power average power tracking mode.

8. The circuitry of claim 1 wherein the switch mode power supply converter is further configured to be in an OFF mode during the low power average power tracking mode.

9. The circuitry of claim 1 wherein:
the power amplifier supply voltage is generated at a modulated power supply output;
the parallel amplifier circuit has a parallel amplifier circuit output; and
a coupling capacitor is coupled between the modulated power supply output and the parallel amplifier circuit output.

10. The circuitry of claim 9 wherein the parallel amplifier circuit comprises a parallel amplifier configured to provide a parallel amplifier output voltage at the parallel amplifier circuit output during the high power modulation mode and the medium power modulation mode.

11. The circuitry of claim 10 wherein the parallel amplifier is further configured to be disabled during the low power average power tracking mode.

12. The circuitry of claim 10 wherein the parallel amplifier output voltage is based on a μC charge pump output voltage during the high power modulation mode and the medium power modulation mode.

13. The circuitry of claim 10 wherein the parallel amplifier has a segmented output stage, such that during the high power modulation mode and the medium power modulation mode, segment selection of the segmented output stage is based on an expected output power from the radio frequency power amplifier.

14. The circuitry of claim 9 wherein the parallel amplifier circuit further comprises a parallel amplifier output bypass switch coupled between the parallel amplifier circuit output and ground, such that:
during the high power modulation mode and the medium power modulation mode, the parallel amplifier output bypass switch is OPEN; and
during the low power average power tracking mode, the parallel amplifier output bypass switch is CLOSED.

15. The circuitry of claim 1 wherein the parallel amplifier circuit comprises a linear regulator configured to provide the power amplifier supply voltage during the low power average power tracking mode.

16. The circuitry of claim 15 wherein the power amplifier supply voltage is based on a μC charge pump output voltage during the low power average power tracking mode.

17. The circuitry of claim 15 wherein the linear regulator is disabled during the medium power modulation mode.

18. The circuitry of claim 15 wherein the linear regulator is disabled during the high power modulation mode.

19. The circuitry of claim 1 wherein the power amplifier supply voltage is further based on a μC charge pump output voltage during the high power modulation mode, during the medium power modulation mode, and during the low power average power tracking mode.

20. The circuitry of claim 19 wherein the parallel amplifier circuit comprises a μC charge pump circuit configured to provide the μC charge pump output voltage based on a battery voltage, wherein the μC charge pump circuit is a capacitor-based charge pump circuit.

21. The circuitry of claim 20 wherein the μC charge pump circuit has a segmented output stage, such that during the high power modulation mode, during the medium power modulation mode, and during the low power average power tracking mode, segment selection of the segmented output stage is based on an expected output power from the radio frequency power amplifier.

22. The circuitry of claim 20 wherein the μC charge pump circuit is further configured to operate using a charge-pump-ratio, which is based on the one of the at least the high power modulation mode, the medium power modulation mode, and the low power average power tracking mode, and is further based on an expected output power from the radio frequency power amplifier.

23. The circuitry of claim 22 wherein during the high power modulation mode, the μC charge pump output voltage is based on the charge-pump-ratio, and is substantially equal to one of the battery voltage and four-thirds times the battery voltage.

24. The circuitry of claim 22 wherein during the medium power modulation mode, the μC charge pump output voltage is based on the charge-pump-ratio, and is substantially equal to one of the battery voltage and two-thirds times the battery voltage.

25. The circuitry of claim 22 wherein during the low power average power tracking mode, the μC charge pump output voltage is based on the charge-pump-ratio, and is substantially equal to one of one-half times the battery voltage, one-third times the battery voltage, and one-fourth times the battery voltage.

26. The circuitry of claim 20 wherein the μC charge pump circuit is further configured to provide a linear regulator output voltage to bias circuitry in the radio frequency power amplifier via a linear regulator.

27. The circuitry of claim 19 wherein the parallel amplifier circuit comprises a μL charge pump circuit configured to provide the μC charge pump output voltage based on a battery voltage, wherein the μL charge pump circuit is an inductor-based charge pump circuit.

28. The circuitry of claim 1 wherein during the low power average power tracking mode, a magnitude of the power amplifier supply voltage is configured to be adjustable based on an expected output power from the radio frequency power amplifier.

29. The circuitry of claim 1 wherein the radio frequency power amplifier is configured to sequentially transmit a plurality of communications slots, such that selection of the one of the at least the high power modulation mode, the medium power modulation mode, and the low power average power tracking mode is based on an expected output power from the radio frequency power amplifier and is made on a communications slot to communications slot basis.

30. The circuitry of claim 1 wherein the radio frequency power amplifier is configured to sequentially transmit a plurality of communications slots, such that during the low power average power tracking mode, adjustment of a magnitude of the power amplifier supply voltage is made on a communications slot to communications slot basis.

31. The circuitry of claim 1 wherein the switch mode power supply converter comprises a segmented output stage, such that during the high power modulation mode and the medium power modulation mode, segment selection of the segmented output stage is based on an expected output power from the radio frequency power amplifier.

32. The circuitry of claim 1 wherein the at least the high power modulation mode, the medium power modulation mode, and the low power average power tracking mode comprises the high power modulation mode, the medium power modulation mode, a medium power average power tracking mode, and the low power average power tracking mode.

33. The circuitry of claim 32 wherein the power management system is further configured to:
operate in the high power modulation mode when an expected output power from the radio frequency power amplifier is greater than a high power modulation mode threshold;
operate in the medium power modulation mode when the expected output power from the radio frequency power amplifier is greater than a medium power modulation mode threshold and is less than the high power modulation mode threshold;
operate in the medium power average power tracking mode when the expected output power from the radio frequency power amplifier is less than the medium power modulation mode threshold and is greater than a low power average power tracking mode threshold; and
operate in the low power average power tracking mode when the expected output power from the radio frequency power amplifier is less than the low power average power tracking mode threshold.

34. The circuitry of claim 32 wherein the parallel amplifier circuit comprises a linear regulator configured to be disabled during the medium power average power tracking mode.

35. The circuitry of claim 32 wherein the parallel amplifier circuit comprises a parallel amplifier configured to provide a parallel amplifier output voltage at a parallel amplifier circuit output during the high power modulation mode and the medium power modulation mode, and is further configured to be disabled during the medium power average power tracking mode and the low power average power tracking mode.

36. A method comprising:
cooperatively operating a switch mode power supply converter with a parallel amplifier circuit to provide a power amplifier supply voltage;
operating in one of at least a high power modulation mode, a medium power modulation mode, and a low power average power tracking mode;
during the high power modulation mode and the medium power modulation mode, controlling the power amplifier supply voltage to a radio frequency power amplifier to provide envelope tracking; and
during the low power average power tracking mode, controlling the power amplifier supply voltage to the radio frequency power amplifier to provide average power tracking.