Multi-stage envelope tracking system with adjusted voltage steps

Abstract

Multi-level envelope tracking systems with adjusted voltage steps are provided. In certain embodiments, an envelope tracking system for generating a power amplifier supply voltage for a power amplifier is provided. The envelope tracking system includes a multi-level supply (MLS) DC-DC converter that outputs a plurality of regulated voltages, a MLS modulator that controls selection of the regulated voltages over time based on an envelope signal corresponding to an envelope of a radio frequency (RF) signal amplified by the power amplifier, and a modulator output filter coupled between an output of the MLS modulator and the power amplifier supply voltage. The envelope tracking system further includes a switching point adaptation circuit configured to control voltage levels of the regulated voltages output by the MLS DC-DC converter based on a power level of the RF signal.

Description

Technical Field

[0001] Embodiments of the present invention relate to electronic systems, and more particularly to power amplifiers for radio frequency (RF) electronic devices. Background Technology

[0002] Power amplifiers are used in RF communication systems to amplify RF signals for transmission via antenna. It is important to manage the power of the RF signal transmission to extend battery life and / or provide an appropriate transmission power level.

[0003] Examples of RF communication systems with one or more power amplifiers include, but are not limited to, mobile phones, tablets, base stations, network access points, customer premises equipment (CPE), laptops, and wearable electronic devices. For example, in wireless devices communicating using cellular phone standards, wireless local area network (WLAN) standards, and / or any other suitable communication standards, power amplifiers can be used to amplify RF signals. RF signals can have frequencies ranging from approximately 30 kHz to 300 GHz, such as the range of approximately 410 MHz to approximately 7.125 GHz used for fifth-generation (5G) communication in Frequency Range 1 (FR1). Summary of the Invention

[0004] In some embodiments, this application relates to an envelope tracking system. The envelope tracking system includes: a power amplifier configured to amplify a radio frequency (RF) signal and receive power from a power amplifier supply voltage; and an envelope tracker configured to generate the power amplifier supply voltage based on an envelope signal corresponding to the envelope of the RF signal. The envelope tracker includes: a DC-DC converter configured to output a plurality of regulated voltages; a modulator configured to control the power amplifier supply voltage based on the plurality of regulated voltages and the envelope signal; and a switching point adaptation circuit configured to control the voltage level of at least one of the plurality of regulated voltages based on the power level of the RF signal.

[0005] In some embodiments, the switching point adaptation circuit is configured to control the voltage level of each of the plurality of regulated voltages based on the power level of the radio frequency signal.

[0006] In various embodiments, the switching point adaptation circuit includes: a power estimation circuit configured to estimate the power level of the radio frequency signal based on a signal power value of at least one of a transmit frame or transmit symbol. According to some embodiments, the signal power value indicates the average power of the transmit frame or symbol. According to several embodiments, the signal power value indicates the peak power of the transmit frame or symbol. According to some embodiments, the switching point adaptation circuit further includes: a voltage estimation circuit configured to estimate a plurality of desired voltage levels associated with the signal power value. According to several embodiments, the switching point adaptation circuit further includes: a programming circuit configured to control the DC-DC converter to output the plurality of regulated voltages, each regulated voltage having a corresponding one of the plurality of desired voltage levels.

[0007] In several embodiments, the envelope tracking system further includes: two or more power amplifiers configured to amplify two or more radio frequency signals, the envelope tracker including two or more modulators, each modulator configured to receive the plurality of regulated voltages and provide modulation to generate a power supply voltage for a corresponding one of the two or more power amplifiers. According to several embodiments, the switching point adaptation circuit is configured to control the voltage level based on the maximum power level of the two or more radio frequency signals.

[0008] In several embodiments, the DC-DC converter is configured to receive a battery voltage and generate multiple regulated voltages based on the DC-DC conversion that provides the battery voltage.

[0009] In some embodiments, each of the plurality of regulated voltages has a different voltage level.

[0010] In various embodiments, the envelope tracker further includes a plurality of decoupling capacitors, each of the decoupling capacitors being coupled between ground and a corresponding one of the plurality of regulated voltages.

[0011] In several embodiments, the modulator includes a plurality of switches, each switch being coupled between a corresponding one of the modulator output voltage and the plurality of regulated voltages.

[0012] In several embodiments, the envelope tracker further includes: a modulator output filter connected between the output of the modulator and the power amplifier supply voltage, the modulator output filter including at least one series inductor and at least one parallel capacitor.

[0013] In some embodiments, this application relates to a mobile device. The mobile device includes: a transceiver configured to generate a radio frequency (RF) transmit signal; front-end circuitry including a power amplifier configured to amplify the RF transmit signal and receive power from a power amplifier supply voltage; and power management circuitry including an envelope tracker configured to generate the power amplifier supply voltage based on an envelope signal corresponding to the envelope of the RF transmit signal. The envelope tracker includes: a DC-DC converter configured to output a plurality of regulated voltages; a modulator configured to control the power amplifier supply voltage based on the plurality of regulated voltages and the envelope signal; and a switching point adaptation circuit configured to control the voltage level of at least one of the plurality of regulated voltages based on the power level of the RF transmit signal.

[0014] In various embodiments, the switching point adaptation circuit is configured to control the voltage level of each of the plurality of regulated voltages based on the power level of the radio frequency transmitted signal.

[0015] In some embodiments, the switching point adaptation circuit includes: a power estimation circuit configured to estimate the power level of the radio frequency transmitted signal based on a signal power value of at least one of the transmitted frames or transmitted symbols. According to several embodiments, the signal power value indicates the average power of the transmitted frame or symbol. According to various embodiments, the signal power value indicates the peak power of the transmitted frame or symbol. According to several embodiments, the switching point adaptation circuit further includes: a voltage estimation circuit configured to estimate a plurality of desired voltage levels associated with the signal power value. According to several embodiments, the switching point adaptation circuit further includes: a programming circuit configured to control the DC-DC converter to output the plurality of regulated voltages, each of the regulated voltages having a corresponding one of the plurality of desired voltage levels.

[0016] In several embodiments, the mobile device further includes: two or more power amplifiers configured to amplify two or more radio frequency (RF) transmit signals, and the envelope tracker includes two or more modulators, each modulator configured to receive the plurality of regulated voltages and provide modulation to generate a power supply voltage for a corresponding one of the two or more power amplifiers. According to various embodiments, the switching point adaptation circuit is configured to control the voltage level based on the maximum power level of the two or more RF transmit signals.

[0017] In some embodiments, the DC-DC converter is configured to receive a battery voltage and generate the plurality of regulated voltages based on a DC-DC conversion that provides the battery voltage.

[0018] In various embodiments, each of the plurality of regulated voltages has a different voltage level.

[0019] In several embodiments, the envelope tracker further includes a plurality of decoupling capacitors, each of the decoupling capacitors being coupled between ground and a corresponding one of the plurality of regulated voltages.

[0020] In some embodiments, the modulator includes a plurality of switches, each of the switches being coupled between a corresponding one of the modulator output voltage and the plurality of regulated voltages.

[0021] In various embodiments, the mobile device further includes: a modulator output filter connected between the output of the modulator and the power amplifier supply voltage, the modulator output filter including at least one series inductor and at least one parallel capacitor.

[0022] In some embodiments, this application relates to an envelope tracking method. The method includes: amplifying a radio frequency (RF) signal using a power amplifier; supplying power to the power amplifier using a power amplifier supply voltage; outputting a plurality of regulated voltages from a DC-DC converter; and controlling the power amplifier supply voltage using a modulator based on the plurality of regulated voltages and an envelope signal corresponding to the envelope of the RF signal. The method further includes: controlling the voltage level of at least one of the plurality of regulated voltages based on the power level of the RF signal.

[0023] In various embodiments, the method further includes controlling each of the plurality of regulated voltages based on the power level of the radio frequency signal.

[0024] In some embodiments, the method further includes estimating the power level of the radio frequency signal based on a signal power value of at least one of the transmitted frames or transmitted symbols. According to several embodiments, the signal power value indicates the average power of the transmitted frame or symbol. According to several embodiments, the signal power value indicates the peak power of the transmitted frame or symbol. According to various embodiments, the method further includes estimating a plurality of desired voltage levels associated with the signal power value. According to several embodiments, the method further includes controlling the DC-DC converter to output the plurality of regulated voltages, each of the regulated voltages having a corresponding one of the plurality of desired voltage levels.

[0025] In several embodiments, the method further includes generating the plurality of regulated voltages based on a DC-DC conversion that provides the battery voltage.

[0026] In various embodiments, each of the plurality of regulated voltages has a different voltage level. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a mobile device according to one embodiment.

[0028] Figure 2 This is a schematic diagram of one implementation of an envelope tracking system for a power amplifier.

[0029] Figure 3A This is a schematic diagram of another embodiment of the envelope tracking system.

[0030] Figure 3B This is a schematic diagram of another embodiment of the envelope tracking system.

[0031] Figure 4 These are voltage versus time graphs for five examples of signal waveforms at different power levels.

[0032] Figure 5A This is an example graph of the power amplifier's supply voltage versus input power.

[0033] Figure 5B This is a graph showing the power-added efficiency (PAE) versus output power for various examples of signal waveforms.

[0034] Figure 6A This is another example of a graph showing the power amplifier's supply voltage versus input power.

[0035] Figure 6B This is a graph showing the PAE versus output power for various examples of signal waveforms, and another example.

[0036] Figure 7 This is a schematic diagram of a mobile device according to another embodiment.

[0037] Figure 8 This is a schematic diagram of one embodiment of a communication system for transmitting radio frequency (RF) signals.

[0038] Figure 9 This is a schematic diagram of a multi-level power supply (MLS) modulation system according to one embodiment.

[0039] Figure 10 This is a schematic diagram of an MLS DC-DC converter according to one embodiment.

[0040] Figure 11 This is a schematic diagram illustrating an example of timing used for MLS DC-DC conversion.

[0041] Figure 12 This is a schematic diagram illustrating an example of MLS envelope tracking for a continuous wave signal. Detailed Implementation

[0042] The following detailed descriptions of certain embodiments present various descriptions of specific embodiments. However, the innovations described herein can be embodied in many different ways, such as those defined and covered by the claims. In this description, reference is made to the accompanying drawings, wherein the same reference numerals may denote the same or functionally similar elements. It should be understood that the elements illustrated in the drawings are not necessarily drawn to scale. Furthermore, it should be understood that some embodiments may include more elements and / or a subset of the elements illustrated in the drawings than are shown in the drawings. In addition, some embodiments may include any suitable combination of features from two or more drawings.

[0043] Envelope tracking is a technique used to improve the power-added efficiency (PAE) of a power amplifier by effectively controlling the voltage level of the power amplifier's supply voltage relative to the envelope of the radio frequency (RF) signal amplified by the power amplifier. Therefore, when the envelope of the RF signal increases, the voltage supplied to the power amplifier can increase. Similarly, when the envelope of the RF signal decreases, the voltage supplied to the power amplifier can decrease to reduce power consumption.

[0044] Envelope tracking can include applications where the envelope signal follows the rapidly changing instantaneous power of an RF signal. In other applications, the envelope signal can be much slower, for example, determined by a longer-term average of the RF signal. For instance, when using symbols via symbol tracking, the envelope signal changes relatively infrequently compared to the rapidly changing instantaneous power of an Orthogonal Frequency Division Multiplexing (OFDM) signal. For example, for 5G OFDM waveforms, the instantaneous power can vary between peaks and troughs in less than 10 ns, while a symbol can change every 16 µs. In some implementations, the envelope signal can be based on the next upcoming peak of the RF signal, thus predicting rather than following the RF power.

[0045] A multi-stage envelope tracking system with adjustable voltage steps is provided. In some embodiments, an envelope tracking system for generating a power amplifier supply voltage for a power amplifier is provided. The envelope tracking system includes: an MLS DC-DC converter that outputs multiple adjustable voltages; an MLS modulator that controls the selection of the adjustable voltages over time based on an envelope signal corresponding to the envelope of an RF signal amplified by the power amplifier; and a modulator output filter coupled between the output of the MLS modulator and the power amplifier supply voltage. The envelope tracking system also includes a switching point adaptation circuit configured to control the voltage level of the adjustable voltages output by the MLS DC-DC converter based on the power level of the RF signal.

[0046] Improved efficiency can be achieved by controlling the voltage level of the regulated voltage based on the power level of the RF signal. For example, the switching point of an MLS DC-DC converter can be adjusted based on the power level of the RF signal to provide predictive adjustment of the regulated voltage, thereby improving efficiency over a wide range of signal power.

[0047] In some implementations, the switching point adaptation circuitry controls the regulated voltage output by the MLS DC-DC converter based on the signal power value indicated for a specific transmission slot or frame. For example, in some systems, the amount of average and / or peak signal power can be known before the transmission slot or frame (e.g., indicated by a base station of the communication network) and can therefore be used to control the voltage level of the regulated voltage.

[0048] Improved performance of multi-level envelope tracking systems can be achieved by adapting discrete voltage levels to appropriate voltage levels (e.g., minimum and maximum voltage values) corresponding to the signal power (e.g., average power) set during a transmit burst or frame. This tracking can be applied to a wide range of transmit scenarios, including but not limited to time-division duplex (TDD).

[0049] Therefore, in some implementations, the power amplifier supply voltage can be controlled based on the expected peak power of the next burst or frame, or even dynamically adjusted during transmission. By controlling the regulated voltage in this way, the size of the selected voltage step can be reduced, allowing for finer tracking of the power amplifier voltage.

[0050] For example, before transmission begins, the peak to average and average power are known, and this knowledge allows for the calculation of the required maximum and minimum voltages. In some implementations, the decoupling capacitors holding charge for each of the regulation voltages used in the MLS DC-DC converter can be pre-charged to the corresponding voltage.

[0051] By implementing an envelope tracking system in this way, enhanced envelope tracking accuracy can be achieved over a wide range of signal power, including during back-off or operation at high and low peak-to-average values.

[0052] In some implementations, the envelope tracking system operates as a power supply capable of switching between multiple voltages to supply a power amplifier via a baseband filter. This power supply is controlled to generate multiple different voltages that are static or fixed compared to the modulation bandwidth of the amplitude of the RF signal waveform passing through the power amplifier. Furthermore, the voltages are adjusted to suit the power amplifier's power requirements (e.g., average power).

[0053] In some implementations, the regulated voltage from the MLS DC-DC converter is processed by two or more MLS modulators to generate power amplifier supply voltages for two or more power amplifiers. For example, carrier aggregation systems, multiple-input multiple-output (MIMO) systems, and / or other communication systems may operate using a shared MLS DC-DC converter. In some implementations, the switching point adaptation circuitry controls the regulated voltage based on the maximum signal power amplified by the power amplifier.

[0054] For example, in MIMO or carrier aggregation scenarios, where multiple power amplifier paths operate simultaneously, the envelope tracking system can select the appropriate voltage magnitude for the power amplifier carrying the highest power. This advantageously allows for reduced power consumption by first adapting the voltage of the branch with the highest power consumption. In some applications, it is advantageous to set a fixed power supply for a power amplifier by using a single modulator switching position for one power amplifier and allowing other voltages to be modulated for a second power amplifier.

[0055] In some implementations, the digital predistortion (DPD) system pre-calculates the voltage settings and predistorts the RF based on knowledge of the power amplifier supply voltage (Vcc) filter characteristics and calibration of the power amplifier response.

[0056] Figure 1 This is a schematic diagram of a mobile device 70 according to one embodiment. The mobile device 70 includes a main antenna 1, a diversity antenna 2, a main antenna tuning circuit 3, a diversity antenna tuning circuit 4, a double-pole double-throw (DPDT) antenna diversity switch 5, a main front-end module 6, a diversity front-end module 7, a battery 8, an MLS envelope tracker 9, a transceiver 10, a baseband modem 11, and an application processor 12.

[0057] Although one embodiment of a mobile device has been shown, the teachings herein apply to mobile devices implemented in a variety of ways. Therefore, other implementations are also possible.

[0058] In the illustrated embodiment, the main front-end module 6 includes a first power amplifier 21, a second power amplifier 22, a third power amplifier 23, a fourth power amplifier 24, a first low-noise amplifier 31, a second low-noise amplifier 32, a third low-noise amplifier 33, a duplexer 42, a transmit / receive band switch 41, a transmit filter 43, a first duplexer 45, a second duplexer 46, a third duplexer 47, a first receive filter 51, a second receive filter 52, a third receive filter 53, a first directional coupler 59, and a second directional coupler 60. Furthermore, the diversity front-end module 7 includes a first low-noise amplifier 35, a second low-noise amplifier 36, a first receive filter 55, a second receive filter 56, a first receive band selection switch 61, and a second receive band selection switch 62.

[0059] Although one embodiment of the front-end circuitry is shown, other implementations of the front-end circuitry are possible. For example, the front-end circuitry may include a power amplifier (PA), a low-noise amplifier (LNA), a filter, a switch, a phase shifter, a duplexer, and / or other suitable circuitry for processing RF signals transmitted and / or received from one or more antennas. Example functions of the front-end include, but are not limited to: amplifying the signal for transmission, amplifying the received signal, filtering the signal, switching between different frequency bands, switching between different power modes, switching between transmit and receive modes, duplexing the signal, multiplexing the signal (e.g., dual-signal or triple-signal), or some combination thereof.

[0060] Therefore, other implementations can be used, such as a main front-end module, a diversity reception front-end module, antenna selection, and / or antenna tuning.

[0061] like Figure 1 As shown, the MLS envelope tracker 9 is used to generate one or more power amplifier supply voltages for a power amplifier used in the mobile device 70 to amplify RF signals for wireless transmission. In the illustrated embodiment, the MLS envelope tracker 9 receives a battery voltage V from the battery 8. BATT And generate the first power amplifier supply voltage V for the first power amplifier 21. PA1 and the second power amplifier power supply voltage V for the first power amplifier 22 PA2 Although an example of the MLS envelope tracker 9 generating two power amplifier supply voltages is shown, the MLS envelope tracker 9 can generate more or fewer power amplifier supply voltages.

[0062] MLS envelope tracker 9 controls the power supply voltage V of the first power amplifier. PA1 This is to track the envelope of the first RF signal amplified by the first power amplifier 21. Furthermore, the MLS envelope tracker 9 controls the power supply voltage V of the second power amplifier. PA2 The MLS envelope tracker 9 tracks the envelope of a second RF signal amplified by the second power amplifier 22. In some embodiments, the MLS envelope tracker 9 receives one or more envelope signals from the baseband modem 11. For example, the MLS envelope tracker 9 may receive a first envelope signal indicating the envelope of a first RF signal and a second envelope signal indicating the envelope of a second RF signal. The envelope signals may be analog or digital.

[0063] Battery 8 can be any suitable battery used in the mobile device 70, including, for example, a lithium-ion battery. Battery voltage V BATT The DC-DC converter of the MLS envelope tracker 9 is regulated to produce a regulated voltage for multi-stage envelope tracking, in accordance with the teachings of this document.

[0064] Transceiver 10 generates RF signals for transmission and processes input RF signals received from main antenna 1 and diversity antenna 2. It is understood that various functions associated with the transmission and reception of RF signals can be handled by [the transceiver unit]. Figure 1 The above refers to one or more components implemented as transceiver 10. In one example, separate components (e.g., separate circuits or dies) may be provided to handle certain types of RF signals.

[0065] The baseband modem 11 provides a digital representation of the transmitted signal to the transceiver 10, which processes it to generate an RF signal for transmission. The baseband modem 11 also processes a digital representation of the received signal provided by the transceiver 10.

[0066] like Figure 1 As shown, the baseband modem 11 is coupled to the application processor 12, which provides primary application processing in the mobile device 70. The application processor 12 can provide a wide range of functions, such as providing system capabilities suitable for supporting applications, including but not limited to memory management, graphics processing, and / or multimedia decoding.

[0067] Although the mobile device 70 illustrates an example of an RF system including a multi-level envelope tracker, a wide variety of RF systems may include multi-level envelope trackers implemented in accordance with the teachings of this document.

[0068] Figure 2-3B Schematic diagrams depict various embodiments of an envelope tracking system for a power amplifier. However, the teachings herein apply to envelope trackers implemented in various ways. Therefore, other implementations are also possible.

[0069] Figure 2 This is a schematic diagram of one embodiment of an envelope tracking system 100 for a power amplifier 71. The envelope tracking system 100 includes an MLS DC-DC converter 72, a switching point adapter circuit 75, an MLS modulator 81, and a modulator output filter 91. The MLS DC-DC converter 72 is also referred to herein as a switching regulator.

[0070] Power amplifier 71 amplifies the RF input signal. IN To generate RF output signal RF OUT The MLS modulator 81 receives an envelope signal (ENVELOPE) relative to the RF input signal. IN The envelope changes.

[0071] In the illustrated embodiment, the MLS DC-DC converter 72 receives the battery voltage V. BATTIt also provides DC-DC conversion to generate various regulated voltages V at different voltage levels. MLSa V MLSb V MLSc ...V MLSn Although four examples of MLS voltages have been described, the MLS DC-DC converter 72 can produce more or fewer MLS voltages, as indicated by the ellipsis.

[0072] MLS modulator 81 receives regulated voltage V MLSa V MLSb V MLSc ...V MLSn The MLS modulator 81 provides the modulator output voltage to the modulator output filter 91 based on the envelope signal and a time-dependent adjustment voltage. In some embodiments, the MLS modulator 81 controls the output voltage based on the envelope signal and a time-dependent selection of an appropriate adjustment voltage. For example, the MLS modulator 81 may include a set of switches for selectively adjusting the adjustment voltage V based on the value of the envelope signal. MLSa V MLSb V MLSc ...V MLSn Connect to the output of the modulator.

[0073] The modulator output filter 91 filters the output of the MLS modulator 81, thereby generating the power amplifier supply voltage V for the power amplifier 71. PA .

[0074] like Figure 2 As shown, the envelope tracking system 100 also includes a switching point adaptation circuit 75, which is based on RF IN The power level of the signal is used to control one or more regulated voltages RF. MLSa V MLSb V MLSc ...V MLSn The voltage level. In some embodiments, the switching point adapter circuit 75 controls the pulse width of the MLS DC-DC converter 72 used for regulation (see, for example...). Figure 11 This controls the switching point of the regulation and the corresponding regulation voltage level.

[0075] By RF IN The power level of the signal is used to control the regulation voltage RF. MLSa V MLSb V MLSc ...V MLSn The voltage level can be adjusted to enhance efficiency. For example, the switching point of the MLS DC-DC converter 72 can be adapted based on the power level of the RF signal, allowing predictive adjustment of the regulating voltage and thus improving efficiency over a wide signal power range.

[0076] In some implementations, the switching point adaptation circuit 75 controls the regulating voltage V based on the amount of transmit power indicated in the transmit frame or time slot. MLSa V MLSb V MLSc ...V MLSn The voltage level. For example, the switching point adapter circuit 75 can receive data indicating the amount of transmit power from a baseband modem or other suitable source.

[0077] Envelope tracking system 100 is well-suited for applications using symbol-by-symbol tracking, which can be applied to high-bandwidth modulation. For example, when using symbol-by-symbol tracking, two MLS voltages can be continuously programmed and used at a symbol rate (e.g., 16 µs in 5G). Therefore, MLS modulator 81 can change the voltage used to generate the power amplifier supply voltage by switching to a new voltage-holding capacitor.

[0078] Figure 3A This is a schematic diagram of another embodiment of the envelope tracking system 150 for power amplifier module 101. The envelope tracking system 150 includes an envelope tracking integrated circuit (IC) 102, a modulator output filter 104, an envelope shaping circuit 105, an envelope signal conditioning circuit 106, a switching point adaptation circuit 109, first to fourth decoupling capacitors 111-114 respectively, and an inductor 117.

[0079] although Figure 3A An embodiment of an envelope tracking system is illustrated, but the teachings herein apply to envelope tracking systems implemented in a wide variety of ways. Therefore, other implementations are also possible.

[0080] In the illustrated embodiment, the envelope tracking IC 102 includes an MLS switching circuit 121, a digital control circuit 122, a baseband MLS modulator 123, and a modulator control circuit 124. Figure 3A The envelope tracking IC 102 is described as having the ability to provide various functions (such as receiving battery voltage (V)). BATT The envelope tracking IC receives switching point adaptation data from switching point adaptation circuit 109, communicates via serial peripheral interface (SPI), receives envelope signals (ENVELOPE), connects to decoupling capacitors 111-114, and connects to various pins or pads of inductor 117. The envelope tracking IC is also referred to herein as an envelope tracking semiconductor wafer or chip.

[0081] MLS switching circuit 121 controls the current through inductor 117 to provide voltage regulation. For example, MLS switching circuit 121 may include a switch and a controller that uses any suitable regulation scheme (including, but not limited to, pulse width modulation) to turn the switch on and off to provide DC-DC conversion. In the illustrated embodiment, MLS switching circuit 121 outputs four stable MLS voltages at different voltage levels. However, MLS switching circuit 121 can be implemented to output more or fewer regulated voltages.

[0082] like Figure 3A As shown, the MLS switching circuit 121 is controlled by a digital control circuit 122. The digital control circuit 122 can provide programmability to the MLS switching circuit 121, the MLS modulator 123, and / or the modulator control circuit 124. For example... Figure 3A As shown, the digital control circuit 122 is coupled to the SPI bus. In some embodiments, the digital control circuit 122 controls the MLS switching circuit 121, the MLS modulator 123, and / or the modulator control circuit 124 based on data received via the SPI bus and / or other chip interfaces.

[0083] The baseband MLS modulator 123 includes a modulator output filter 104 coupled to the power amplifier supply voltage V. PA The output of the modulator. In some embodiments, the baseband MLS modulator 123 includes a switch coupled between each of the stabilizing MLS voltages and the modulator output filter 104. Furthermore, the modulator switches are selectively opened or closed by the modulator controller 124 based on the envelope signal.

[0084] In the illustrated embodiment, the modulator output filter 104 includes a first series inductor 127, a second series inductor 128, a first parallel capacitor 125, and a second parallel capacitor 126. Although in Figure 3A The example implementation of a modulator output filter is described herein, but the teachings herein apply to modulator output filters implemented in a wide variety of ways. Therefore, other implementations of the filter can be used in accordance with the teachings herein.

[0085] In some implementations, one or more components of the filter are controllable (e.g., digitally programmable and / or analog tuned) to provide enhanced flexibility and / or configurability. For example, in the illustrated embodiment, the first parallel capacitor 125 and the second parallel capacitor 126 have controllable capacitance values. While two examples of controllable filter elements are shown, other filter components may also be additionally or alternatively made controllable.

[0086] In the illustrated embodiment, power amplifier module 101 includes a power amplifier 107 and a power supply voltage filter 108. The power supply voltage filter 108 includes a series inductor 133, a first parallel capacitor 131, and a second parallel capacitor 132. While one embodiment of the power amplifier module is shown, the teachings herein apply to power amplifier modules implemented in a wide variety of ways. Therefore, other implementations are also possible.

[0087] like Figure 3A As shown, the switching point adaptation circuit 109 includes a power estimation circuit 141, a voltage estimation circuit 142, and an MLS programming circuit 143. The power estimation circuit 141 operates to estimate the RF signal RF. IN The signal power. In some embodiments, the power estimation circuit 141 receives digital data indicating the signal power associated with a particular transmit frame or time slot.

[0088] Voltage estimation circuit 142 operates to estimate the desired voltage level of one or more stable output voltages of MLS switching circuit 121 based on the estimated power. MLS programming circuit 143 operates to program MLS switching circuit 121 based on the estimated voltage. In the illustrated embodiment, MLS switching circuit 121 is programmed on an interface separate from the SPI bus. In another embodiment, switching point adapter circuit 109 programs MLS switching circuit 121 to envelope tracking IC 102 on the SPI bus and / or other common interface.

[0089] Although one embodiment of a switching point adapter circuit is shown, the teachings herein apply to switching point adapter circuits implemented in a wide variety of ways.

[0090] Figure 3B This is a schematic diagram of another embodiment of the envelope tracking system 160. The envelope tracking system 160 includes an envelope tracking IC 152, a first modulator output filter 104a, a second modulator output filter 104b, a first envelope shaping circuit 105a, a second envelope shaping circuit 105b, a first envelope signal conditioning circuit 106a, a second envelope signal conditioning circuit 106b, a switching point adaptation circuit 109, first to fourth decoupling capacitors 111-114 respectively, and an inductor 117. The envelope tracking system 160 generates a first power amplifier supply voltage V for the first power amplifier module 101a. PA1 And the second power amplifier power supply voltage V for the second power amplifier module 101b PA2 .

[0091] In the illustrated embodiment, the envelope tracking IC 152 includes an MLS switching circuit 121, a digital control circuit 122, a first baseband MLS modulator 123a, a second baseband MLS modulator 123b, a first modulator control circuit 124a, and a second modulator control circuit 124b.

[0092] Figure 3B The envelope tracking system 160 is similar to Figure 3A The envelope tracking system 150, in addition to the envelope tracking system 160, illustrates one embodiment in which a common or shared MLS DC-DC converter is used in conjunction with multiple modulators to generate multiple power amplifier supply voltages.

[0093] In some implementations, the regulated voltage from the MLS DC-DC converter is processed by two or more MLS modulators to generate power amplifier supply voltages for two or more power amplifiers. In some implementations, the switching point adapter circuitry controls the regulated voltage based on the maximum signal power amplified by the power amplifiers.

[0094] Figure 4 These are voltage versus time graphs for five examples of signal waveforms at different power levels. The examples depict waveforms used in an MCS020MHz WLAN with five levels and a 30MHz power filter bandwidth.

[0095] like Figure 4 As shown, the five voltage levels in this example are set based on the signal amplitude so that the minimum and maximum voltage levels match the time-varying waveform. For example, Figure 4 Five different voltage magnitudes for pulses tracking amplitude versus time were depicted for five different average powers.

[0096] Figure 5A This is an example graph of the power amplifier's supply voltage versus input power. The example shows the voltage magnitude for a 24dBm power output without a matching voltmeter. The voltage steps are between 1.7V and 5.5V, where 5.5V corresponds to a maximum peak power of 35dBm, satisfying a typical LTE waveform with an average output power of 30.5dBm.

[0097] Figure 5B This is a graph showing the power-added efficiency (PAE) versus output power for various examples of signal waveforms.

[0098] Choosing a single voltage for each power on the x-axis results in selecting an efficiency curve at each power for a given voltage. The combination of these single voltage choices for each power is plotted as a sawtooth-shaped superimposed efficiency curve, representing the achievable power amplifier efficiency of the system.

[0099] This example shows the results for various waveforms, with the power amplifier efficiency averaging around 35% at 24 dBm.

[0100] Figure 6A This is another example of a power amplifier supply voltage versus input power graph. This example shows a voltage magnitude of 24dBm with an adapted voltage step. The voltage step is between 1.7V and 2.7V, where 2.7V corresponds to a maximum peak power of 28.5dBm, satisfying a typical LTE waveform with an average output power of 24dBm.

[0101] Figure 6B This is a graph showing the PAE versus output power for various examples of signal waveforms. This example illustrates the results for various waveforms, where the power amplifier efficiency averages approximately 42% at 24 dBm. This is compared to... Figure 5B A significant improvement in the associated 35% efficiency figure. This is achieved by selecting a lower voltage that precisely adapts to the 24dBm average transmit power, resulting in a substantial increase in power amplifier efficiency.

[0102] Figure 7 This is a schematic diagram of a mobile device 800 according to another embodiment. The mobile device 800 includes a baseband system 801, a transceiver 802, a front-end system 803, an antenna 804, a power management system 805, a memory 806, a user interface 807, and a battery 808.

[0103] Mobile devices 800 can communicate using a variety of communication technologies, including but not limited to 2G, 3G, 4G (LTE, LTE Advanced, and LTE-Advanced Pro), 5G NR, WLAN (e.g., WiFi), WPAN (e.g., Bluetooth and ZigBee), WMAN (e.g., WiMax), and / or GPS technologies.

[0104] Transceiver 802 generates RF signals for transmission and processes incoming RF signals received from antenna 804. It should be understood that various functions associated with the transmission and reception of RF signals can be implemented through... Figure 8 The overall representation is obtained by referring to one or more components of transceiver 802. In one example, different components (e.g., different circuits or chips) may be provided for processing specific types of RF signals.

[0105] The front-end system 803 assists in regulating signals transmitted to and / or received from the antenna 804. In the illustrated embodiment, the front-end system 803 includes a phase shifter 810, a power amplifier (PA) 811, a low-noise amplifier (LNA) 812, a filter 813, a switch 814, and a duplexer 815. However, other implementations are also possible.

[0106] For example, the front-end system 803 may provide functions including, but not limited to, amplifying the signal for transmission, amplifying the signal for reception, filtering the signal, switching between different frequency bands, switching between different power modes, switching between transmission and reception modes, signal duplexing, signal multiplexing (e.g., dual-signal or triple-signal), or some combination thereof.

[0107] In some implementations, the mobile device 800 supports carrier aggregation, thereby providing flexibility to increase peak data rates. Carrier aggregation can be used in both frequency division duplex (FDD) and time division duplex (TDD) modes, and can be used to aggregate multiple carriers or channels. Carrier aggregation includes contiguous aggregation, where consecutive carriers with the same operating frequency band are aggregated. Carrier aggregation can also be non-contiguous and can include carriers frequency-separated in a common frequency band or different frequency bands.

[0108] Antenna 804 may include antennas for a wide variety of types of communication. For example, antenna 804 may include antennas associated with transmitting and / or receiving signals related to a wide variety of frequencies and communication standards.

[0109] In some implementations, antenna 804 supports MIMO communication and / or switching diversity communication. For example, MIMO communication uses multiple antennas to transmit multiple data streams via a single radio frequency channel. MIMO communication benefits from higher signal-to-noise ratios, improved coding, and / or reduced signal interference due to spatial multiplexing differences in the radio environment. Switching diversity refers to communication that selects a specific antenna to operate at a specific time. For example, a switch can be used to select a specific antenna from an antenna array based on various factors, such as observed bit error rate and / or signal strength indicators.

[0110] In some embodiments, the mobile device 800 may operate with beamforming. For example, the front-end system 803 may include a phase shifter with a variable phase controlled by the transceiver 802. Furthermore, the phase shifter is controlled to provide beamforming and directivity for the transmission and / or reception of signals using the antenna 804. For example, in the case of signal transmission, the phase of the transmitted signal supplied to the antenna 804 is controlled such that the radiated signal from the antenna 804 uses a combination of constructive and destructive interference to produce a converged transmitted signal exhibiting similar beam quality with greater signal strength propagating in a given direction. In the case of signal reception, the phase is controlled such that more signal energy is received when the signal arrives at the antenna 804 from a particular direction. In some embodiments, the antenna 804 includes one or more arrays of antenna elements to enhance beamforming.

[0111] Baseband system 801 is coupled to user interface 807 to facilitate the handling of various user inputs and outputs (I / O), such as voice and data. Baseband system 801 provides a transceiver 802 with a digital representation of the transmitted signal, which processes the digital representation to generate an RF signal for transmission. Baseband system 801 also processes a digital representation of the received signal provided by transceiver 802. Figure 7 As shown, the baseband system 801 is coupled to the memory 806 to facilitate the operation of the mobile device 800.

[0112] The memory 806 can be used for a variety of purposes, such as storing data and / or instructions to facilitate the operation of the mobile device 800 and / or providing storage of user information.

[0113] The power management system 805 provides multiple power management functions for the mobile device 800. The power management system 805 may include an MLS envelope 860 implemented according to one or more features of this application.

[0114] like Figure 7 As shown, the power management system 805 receives battery voltage from the battery 808. The battery 808 can be any suitable battery for the mobile device 800, including, for example, a lithium-ion battery.

[0115] Figure 8This is a schematic diagram of one embodiment of a communication system 950 for transmitting RF signals. The communication system 950 includes a battery 901, an MLS envelope tracker 902, a power amplifier 903, a directional coupler 904, a duplex and switching circuit 905, an antenna 906, a baseband processor 907, a signal delay circuit 908, a digital predistortion (DPD) circuit 909, an I / Q modulator 910, an observation receiver 911, an intermodulation detection circuit 912, an envelope delay circuit 921, a coordinate rotation digital computation (CORDIC) circuit 922, a shaping circuit 923, a digital-to-analog converter 924, and a reconstruction filter 925.

[0116] Figure 8 The communication system 950 illustrates an example of an RF system that may include an envelope tracking system implemented according to one or more features of this application. However, the teachings herein are applicable to RF systems implemented in a wide variety of ways.

[0117] Baseband processor 907 operates to generate in-phase (I) and quadrature-phase (Q) signals, which correspond to the signal components of a sine wave or signals with desired amplitude, frequency, and phase. For example, the I and Q signals provide an equivalent representation of a sine wave. In some embodiments, the I and Q signals are output in digital format. Baseband processor 907 can be any suitable processor for processing baseband signals. For example, baseband processor 907 may include a digital signal processor, a microprocessor, a programmable core, or any combination thereof.

[0118] The signal delay circuit 908 provides adjustable delays to the I and Q signals to help control the differential envelope signals ENV_p and ENV_n supplied to the MLS envelope tracker 902 and the RF signal RF supplied to the power amplifier 903. IN The relative alignment between them. The delay provided by the signal delay circuit 908 is controlled based on the intermodulation of adjacent frequency bands detected by the intermodulation detection circuit 912.

[0119] The DPD circuit 909 operates to provide digital shaping to the delayed I and Q signals from the signal delay circuit 908 to generate digitally predistorted I and Q signals. In the illustrated embodiment, the DPD provided by the DPD circuit 909 is controlled based on the intermodulation amount detected by the intermodulation detection circuit 912. The DPD circuit 909 is used to reduce the distortion of the power amplifier 903 and / or improve the efficiency of the power amplifier 903.

[0120] The I / Q modulator 910 receives digital predistorted I and Q signals, which are processed to generate an RF signal. INFor example, the I / Q modulator 910 may include a DAC configured to convert digital predistorted I and Q signals into analog format, a mixer for upconverting analog I and Q signals to radio frequency, and a converter for combining the upconverted I and Q signals into an RF signal. IN The signal synthesizer. In some embodiments, the I / Q modulator 910 may include one or more filters configured to filter the frequency content of the signal being processed.

[0121] Envelope delay circuit 921 delays the I and Q signals from baseband processor 907. Furthermore, CORDIC circuit 922 processes the delayed I and Q signals to generate an RF signal. IN The digital envelope signal of the envelope. Although Figure 8 The illustration shows an implementation using the CORDIC circuit 922, but the envelope signal can also be obtained in other ways.

[0122] Shaping circuit 923 operates to shape the digital envelope signal to enhance the performance of communication system 950. In some embodiments, shaping circuit 923 includes a shaping table that maps each level of the digital envelope signal to a corresponding shaped envelope signal level. Envelope shaping can help control the linearity, distortion, and / or efficiency of power amplifier 903.

[0123] In the illustrated embodiment, the shaped envelope signal is a digital signal converted by DAC 924 into a differential analog envelope signal. Furthermore, the differential analog envelope signal is filtered by reconstruction filter 925 to produce differential envelope signals ENV_p and ENV_n suitable for use by the differential envelope amplifier of MLS envelope tracker 902. In some embodiments, reconstruction filter 925 includes a differential low-pass filter.

[0124] Although an example of an envelope signal is shown, the teachings of this paper apply to envelope signals implemented in various ways. For example, in another example, the DAC 924 and reconstruction filter 925 are omitted to facilitate the provision of digital envelope data to the MLS envelope tracker 902.

[0125] Continue to refer to Figure 8 The MLS envelope tracker 902 receives the envelope signal from the reconstruction filter 925 and the battery voltage V from the battery 901. BATT The differential envelope signals ENV_p and ENV_n are used to generate the power amplifier supply voltage V for the power amplifier 903. CC_PA In this example, power amplifier 903 receives the RF signal RF from I / Q modulator 910. IN The amplified RF signal is then supplied to the antenna 906 via the duplex and switching circuit 905. OUT .

[0126] A directional coupler 904 is located between the output of power amplifier 903 and the input of duplex and switching circuit 905, thereby allowing measurement of the output power of power amplifier 903 excluding the insertion loss of duplex and switching circuit 905. The induced output signal from directional coupler 904 is provided to observation receiver 911, which may include a mixer for providing down-conversion to generate down-converted I and Q signals, and a DAC for generating I and Q observation signals from the down-converted I and Q signals.

[0127] Intermodulation detection circuit 912 determines the intermodulation products between the observed I and Q signals and the I and Q signals from baseband processor 907. Furthermore, intermodulation detection circuit 912 controls the delay of DPD and / or signal delay circuit 908 provided by DPD circuit 909 to control the differential envelope signals ENV_p, ENV_n, and RF signal RF. IN The relative alignment between them. In another embodiment, the intermodulation detection circuit 912 additionally or alternatively controls the delay of the signal delay circuit 921.

[0128] Through feedback paths including the output from power amplifier 903 and baseband, the I and Q signals can be dynamically adjusted to optimize the operation of communication system 950. For example, configuring communication system 950 in this way can help provide power control, compensate for transmitter impairments, and / or perform DPD.

[0129] Although illustrated as a single stage, power amplifier 903 may include one or more stages. Furthermore, the teachings herein apply to communication systems that include multiple power amplifiers.

[0130] Figure 9 This is a schematic diagram of an MLS modulation system 1050 according to one embodiment. The MLS modulation system 1050 includes a modulator control circuit 1020, an MLS DC-DC converter 1025, a modulator switch group 1027, and a decoupling capacitor group 1030.

[0131] Figure 9 The MLS modulation system 1050 illustrates one embodiment of an MLS modulator circuit suitable for incorporation into a multi-stage envelope tracker. However, other embodiments of the MLS modulator circuit may be included in a multi-stage envelope tracker implemented according to the teachings herein.

[0132] The MLS DC-DC converter 1025 is based on providing battery voltage V. BATT The DC-DC conversion generates the first regulated voltage V. MLS1 Second regulating voltage V MLS2 and the third regulating voltage V MLS3Although an example with three regulated voltages is shown, the MLSDC-DC converter 1025 can produce more or fewer regulated voltages. In some implementations, relative to the battery voltage V... BATT At least a portion of the regulated voltage is increased. Additionally or alternatively, one or more regulated voltages are below the battery voltage V. BATT Voltage drop-off voltage.

[0133] The decoupling capacitor bank 1030 helps stabilize the regulated voltage generated by the MLS DC-DC converter 1025. For example, Figure 9 The decoupling capacitor bank 1030 includes a first regulated voltage V for decoupling. MLS1 The first decoupling capacitor 1031 is used to decouple the second regulating voltage V. MLS2 The second decoupling capacitor 1032, and the third regulating voltage V for decoupling MLS3 The third decoupling capacitor is 1033.

[0134] Continue to refer to Figure 9 The modulator switch group 1027 includes connections to the output (MOD) of the modulator. OUT ) and the first regulating voltage V MLS1 The first switch 1041 is connected to the output of the modulator and the second regulated voltage V. MLS2 The second switch 1042 between, and the output of the modulator and the third regulated voltage V MLS3 The third switch 1043 is between the switches 1041-1043. The modulator control 1020 operates to selectively open or close the switches 1041-1043, thereby controlling the output of the modulator.

[0135] Figure 10 This is a schematic diagram of an MLS DC-DC converter 1073 according to one embodiment. The MLS DC-DC converter 1073 includes an inductor 1075, a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, and a sixth switch S6. The MLS DC-DC converter 1073 further includes control circuitry for opening or closing the switches to provide regulation. Figure 10 (Not shown in the image).

[0136] Figure 10 The MLS DC-DC converter 1073 illustrates one implementation of an MLS DC-DC converter suitable for incorporation into a multi-stage envelope tracker. However, other implementations of the MLS DC-to-DC converter may include a multi-stage envelope tracker implemented according to the teachings herein.

[0137] In the illustrated embodiment, the first switch S1 includes a connection electrically connected to the battery voltage V. BATTThe first terminal, and the second terminal electrically connected to the first terminal of the second switch S2 and the first terminal of the inductor 1075. The second switch S2 further includes a terminal electrically connected to a first or grounded power supply V. GND The second end. Although Figure 10 The illustration shows a configuration of a DC-DC converter powered using a grounded power supply and a battery voltage, but the teachings herein apply to DC-DC converters powered using any suitable power supply. Inductor 1075 further includes a second terminal electrically connected to the first terminal of each of the third to sixth switches S3-S6. The third switch S3 further includes a terminal electrically connected to the grounded power supply V. GND The second terminal. The fourth, fifth, and sixth switches S4-S6 each include a configuration to generate the first, second, and third regulated voltages V, respectively. MLS1 V MLS2 and V MLS3 The second end.

[0138] The first to sixth switches S1-S6 are selectively opened or closed to maintain the regulated voltage within a specific error tolerance of the target voltage level. Although an example with three regulated voltages is shown, the MLS DC-DC converter 1073 can be implemented to produce more or fewer regulated voltages.

[0139] In the illustrated embodiment, the MLS DC-DC converter 1073 operates as a buck-boost converter, which is operable to generate a voltage greater than the battery voltage V. BATT Adjust the boost voltage and / or lower it than the battery voltage V BATT The voltage drop is adjusted. However, other implementations are possible.

[0140] Figure 11 This is a schematic diagram illustrating an example of timing used in MLS DC-to-DC conversion. (Example:) Figure 11 As shown, the width of the regulation period can be used to control the voltage level of the regulated voltage generated by the MLS DC-DC converter. For example, one MLS regulated voltage can be associated with period t1, while a second regulated voltage can be associated with a different period t2. Furthermore, non-overlapping periods (tovlp) can be used to avoid crowbar current between different voltage levels.

[0141] In some embodiments herein, one or more adjustment periods (e.g., t1 and / or t2) and / or one or more non-overlapping periods (e.g., tovlop) are digitally controllable. In some embodiments, the delay is controlled based on a digital state machine and / or other suitable circuitry.

[0142] The regulated voltage generated by the MLS DC-DC converter can be selectively supplied to the modulator output filter by the modulator. In the illustrated example, the modulator output filter is depicted as including parallel capacitors C1 and C2 and series inductors L1 and L2. However, other implementations of the modulator output filter are also possible.

[0143] Figure 12 This is a schematic diagram illustrating an example of MLS envelope tracking for a continuous wave signal. The example shown is for a continuous wave signal with a frequency of approximately 100 MHz and a corresponding period of approximately 10 ns. An example of a suitable MLS voltage level for the signal is shown.

[0144] Summarize

[0145] The embodiments described above have provided examples relating to mobile devices. However, the principles and advantages of these embodiments can be applied to any other system or device that requires envelope tracking.

[0146] Unless the context explicitly requires otherwise, throughout the specification and claims, the words “comprising,” “including,” and similar terms are interpreted in an inclusive sense, contrary to their exclusive or exclusionary meaning; that is, in the sense of “including, but not limited to.” As is generally used herein, the word “coupled” refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Similarly, as is generally used herein, the word “connected” refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Furthermore, when applicable in this application, the words “in this document,” “above,” “below,” and similar terms should refer to the application as a whole and not to any particular part of the application. When the context permits, the words used in the above detailed description in singular or plural form may also include both singular and plural forms, respectively. The word “or” when referring to a list of two or more items covers all of the following interpretations: any item in the list, all items in the list, and any combination of items in the list.

[0147] Furthermore, unless otherwise stated or understood in the context, the conditional language used herein, such as “may,” “possibly,” “might,” “can,” “example,” “such as,” and similar terms, is generally intended to express that certain embodiments include certain features, elements, and / or states that are not included in other embodiments. Therefore, such conditional language is not generally intended to imply that features, elements, and / or states are necessary in any way for one or more embodiments, or that one or more embodiments must include logic for determining whether such features, elements, and / or states are included or performed in any particular embodiment, with or without author input or prompting.

[0148] The above detailed description of embodiments of the present invention is not intended to be exhaustive or to limit the invention to the precise forms disclosed above. While specific embodiments and examples of the invention have been described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as will be recognized by those skilled in the art. For example, although processes or blocks are presented in a given order, alternative embodiments may execute routines with steps in a different order, or employ a system with blocks, and some processes or blocks may be deleted, moved, added, subdivided, combined, and / or modified. Each of these processes or blocks can be implemented in various different ways. Furthermore, although processes or blocks are sometimes shown to be executed serially, these processes or blocks may instead be executed in parallel, or may be executed at different times.

[0149] The teachings of this invention provided herein can be applied to other systems, not necessarily those described above. The elements and behaviors of the various embodiments described above can be combined to provide further embodiments.

[0150] Although certain embodiments of the invention have been described, these embodiments are presented by way of example only and are not intended to limit the scope of this application. In fact, the novel methods and systems described herein can be implemented in various other ways; furthermore, various omissions, substitutions, and changes can be made to the forms of the methods and systems described herein without departing from the spirit of this application. The appended claims and their equivalents are intended to cover any forms or modifications that fall within the scope and spirit of this application.

Claims

1. An envelope tracking system, comprising: A power amplifier configured to amplify radio frequency signals and receive power from the power amplifier supply voltage; as well as An envelope tracker is configured to generate the power amplifier supply voltage based on an envelope signal corresponding to the envelope of the radio frequency signal. The envelope tracker includes a DC-DC converter configured to output a plurality of regulated voltages, a modulator configured to control the power amplifier supply voltage according to the plurality of regulated voltages and the envelope signal, and a switching point adapter circuit configured to control the voltage level of at least one of the plurality of regulated voltages based on the power level of the radio frequency signal. The switching point adapter circuit is configured to control the pulse width of the DC-DC converter, thereby controlling the level of the regulated voltages.

2. The envelope tracking system according to claim 1, wherein, The switching point adaptation circuit is configured to control the voltage level of each of the plurality of regulated voltages based on the power level of the radio frequency signal.

3. The envelope tracking system according to claim 1, wherein, The switching point adaptation circuit includes a power estimation circuit configured to estimate the power level of the radio frequency signal based on the signal power value of at least one of the transmit frames or transmit symbols.

4. The envelope tracking system according to claim 3, wherein, The signal power value indicates the average power.

5. The envelope tracking system according to claim 3, wherein, The signal power value indicates the peak power.

6. The envelope tracking system according to claim 3, wherein, The switching point adaptation circuit further includes a voltage estimation circuit configured to estimate a plurality of desired voltage levels associated with the signal power value.

7. The envelope tracking system according to claim 6, wherein, The switching point adaptation circuit further includes a programming circuit configured to control the DC-DC converter to output the plurality of regulated voltages, each regulated voltage having a corresponding one of the plurality of desired voltage levels.

8. The envelope tracking system according to claim 1, comprising: Two or more power amplifiers configured to amplify two or more radio frequency signals, the envelope tracker including two or more modulators, each modulator configured to receive the plurality of regulated voltages and provide modulation to generate a power supply voltage for a corresponding one of the two or more power amplifiers.

9. The envelope tracking system according to claim 8, wherein, The switching point adaptation circuit is configured to control the voltage level based on the maximum power level of the two or more radio frequency signals.

10. The envelope tracking system according to claim 1, wherein, Each of the plurality of regulated voltages has a different voltage level.

11. The envelope tracking system according to claim 1, wherein, The modulator includes a plurality of switches, each switch being coupled between the output of the modulator and a corresponding one of the plurality of regulated voltages.

12. The envelope tracking system according to claim 1, further comprising: A modulator output filter is connected between the output of the modulator and the power amplifier supply voltage, the modulator output filter comprising at least one series inductor and at least one parallel capacitor.

13. A mobile device, comprising: Transceiver, configured to generate radio frequency transmission signals; The front-end circuitry includes a power amplifier configured to amplify the radio frequency transmitted signal and receive power from the power amplifier supply voltage; as well as A power management circuit includes an envelope tracker configured to generate a power amplifier supply voltage based on an envelope signal corresponding to the envelope of the radio frequency transmitted signal. The envelope tracker includes a DC-DC converter configured to output a plurality of regulated voltages, a modulator configured to control the power amplifier supply voltage based on the plurality of regulated voltages and the envelope signal, and a switching point adapter circuit configured to control the voltage level of at least one of the plurality of regulated voltages based on the power level of the radio frequency transmitted signal. The switching point adapter circuit is configured to control the pulse width of the DC-DC converter, thereby controlling the level of the regulated voltages.

14. The mobile device according to claim 13, wherein, The switching point adaptation circuit includes a power estimation circuit configured to estimate the power level of the radio frequency transmitted signal based on the signal power value of at least one of the transmitted frames or transmitted symbols.

15. The mobile device according to claim 14, wherein, The switching point adaptation circuit further includes a voltage estimation circuit configured to estimate a plurality of desired voltage levels associated with the signal power value.

16. The mobile device according to claim 15, wherein, The switching point adaptation circuit further includes a programming circuit configured to control the DC-DC converter to output the plurality of regulated voltages, each regulated voltage having a corresponding one of the plurality of desired voltage levels.

17. The mobile device according to claim 13, comprising: Two or more power amplifiers configured to amplify two or more radio frequency transmit signals, the envelope tracker including two or more modulators, each modulator configured to receive the plurality of regulated voltages and provide modulation to generate a power supply voltage for a corresponding one of the two or more power amplifiers.

18. The mobile device according to claim 17, wherein, The switching point adaptation circuit is configured to control the voltage level based on the maximum power level of the two or more radio frequency transmission signals.

19. A method for envelope tracking, the method comprising: Use a power amplifier to amplify the radio frequency signal; The power amplifier is powered using the power amplifier power supply voltage; Output multiple regulated voltages from a DC-DC converter; The power amplifier power supply voltage is controlled using a modulator based on the plurality of regulated voltages and envelope signals, the envelope signals corresponding to the envelope of the radio frequency signal; as well as The voltage level of at least one of the plurality of regulated voltages is controlled based on the power level of the radio frequency signal. The voltage level of at least one of the plurality of adjustable voltages is controlled by controlling the pulse width of the DC-DC converter.

20. The method of claim 19, further comprising: The power level of the radio frequency signal is estimated based on the signal power value of at least one of the transmitted frames or transmitted symbols, and multiple expected voltage levels associated with the signal power value are estimated.

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