Multi-stage envelope tracking with analog interface

Abstract

Provided herein are multi-level envelope trackers with analog interfaces. 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, an MLS modulator that controls selection of the regulated voltages over time based on an analog envelope signal corresponding to an envelope of an 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.

Description

Technical Field

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

[0002] In RF communication systems, power amplifiers are used to amplify the RF signals transmitted via antennas. Managing the power of RF signal transmission to extend battery life and / or provide appropriate transmission power levels is important.

[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 standards, wireless local area network (WLAN) standards, and / or any other suitable communication standards, power amplifiers can be used to amplify RF signals. For fifth-generation (5G) cellular communication in Frequency Range 1 (FR1), the RF signal can have frequencies ranging from approximately 30 kHz to 300 GHz, such as frequencies ranging from approximately 410 MHz to approximately 7.125 GHz. Summary of the Invention

[0004] In some embodiments, this disclosure 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 analog 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 generate a modulator output voltage at its output based on the plurality of regulated voltages and the envelope signal; and a modulator output filter coupled between the modulator output and the power amplifier supply voltage, the modulator being configured to generate the modulator output voltage based on comparing the analog envelope signal with a plurality of signal thresholds.

[0005] In some embodiments, the modulator includes a plurality of switches that are selectively activated based on comparisons of an analog envelope signal with a plurality of signal thresholds. According to several embodiments, each of the plurality of switches is connected between the output of the modulator and a corresponding one of a plurality of regulated voltages.

[0006] In various embodiments, the envelope tracker further includes: a plurality of modulators, each including a modulator; and a plurality of modulator output filters, each including a modulator output filter, wherein each of the plurality of modulators is coupled to a power amplifier supply voltage via a corresponding one of the plurality of modulator output filters. According to various embodiments, the effective number of the plurality of modulators is selected based on comparing an analog envelope signal with a plurality of signal thresholds.

[0007] In several embodiments, the modulator is configured to receive a simulated envelope signal via a mobile industry peripheral interface analog reference interface for envelope tracking.

[0008] In some embodiments, the analog envelope signal is a differential envelope signal. According to several embodiments, the modulator includes a differential envelope amplifier configured to amplify the differential envelope signal to generate a single-ended envelope signal. According to various embodiments, the modulator also includes a plurality of comparators, each configured to compare the single-ended envelope signal with a corresponding one of a plurality of signal thresholds. According to several embodiments, the differential envelope amplifier includes: an amplification circuit configured to amplify the differential envelope signal; and a common-mode feedback circuit operable to compensate the amplification circuit for common-mode errors caused by a common-mode voltage of the differential envelope signal. According to several embodiments, the amplification circuit includes a first differential input configured to receive the differential envelope signal and a second differential input configured to receive a differential compensation signal from the common-mode feedback circuit. According to various embodiments, the common-mode feedback circuit is configured to provide feedback from the output of the amplification circuit to the second differential input of the amplification circuit. According to several embodiments, the differential envelope amplifier also includes a differential input filter configured to filter the differential envelope signal before amplification by the amplification circuit.

[0009] In some embodiments, each of the plurality of signal thresholds is controllable.

[0010] In various embodiments, the envelope tracker further includes a DC path filter coupled between the DC voltage and the power amplifier supply voltage. According to several embodiments, the DC-DC converter is also configured to generate a DC voltage. According to several embodiments, the DC-DC converter is configured to receive a battery voltage and generate multiple regulated voltages and a DC voltage based on the DC-DC conversion providing the battery voltage. According to several embodiments, the DC path filter includes at least one series inductor and at least one parallel capacitor. According to some embodiments, the DC path through the DC path filter carries at least 75 percent of the energy supplied from the envelope tracker to the power amplifier.

[0011] In several embodiments, each of the plurality of regulated voltages has a different voltage level.

[0012] In some embodiments, the envelope tracker further includes a plurality of decoupling capacitors, each decoupling capacitor being coupled between ground and a corresponding one of a plurality of regulated voltages.

[0013] In various embodiments, the modulator output filter includes at least one series inductor and at least one parallel capacitor. According to several embodiments, the modulator output filter also includes a DC blocking capacitor connected in series between the modulator output voltage and the power amplifier supply voltage.

[0014] In some embodiments, this disclosure relates to an envelope tracker. The envelope tracker includes: a power amplifier power supply voltage terminal configured to output a power amplifier power supply voltage for a power amplifier; a DC-DC converter configured to output a plurality of regulated voltages based on a regulated battery voltage; a modulator output filter; and a modulator including an output coupled to the power amplifier power supply voltage terminal via the modulator output filter. The modulator is configured to generate a modulator output voltage at the output based on the plurality of regulated voltages and an analog envelope signal, and to generate the modulator output voltage based on comparing the analog envelope signal with a plurality of signal thresholds.

[0015] In some embodiments, the modulator includes a plurality of switches selectively activated based on comparing an analog envelope signal with a plurality of signal thresholds. According to various embodiments, each of the plurality of switches is connected between the output of the modulator and a corresponding one of a plurality of regulated voltages. According to various embodiments, the envelope tracker further includes: a plurality of modulators, comprising modulators; and a plurality of modulator output filters, comprising modulator output filters, each of the plurality of modulators being coupled to a power amplifier power supply voltage terminal via a corresponding one of the plurality of modulator output filters. According to several embodiments, the effective number of the plurality of modulators is selected based on comparing the analog envelope signal with a plurality of signal thresholds.

[0016] In various embodiments, the modulator is configured to receive analog envelope signals via a mobile industry peripheral interface analog reference interface for envelope tracking.

[0017] In some embodiments, the analog envelope signal is a differential envelope signal. According to several embodiments, the modulator includes a differential envelope amplifier configured to amplify the differential envelope signal to generate a single-ended envelope signal. In several embodiments, the modulator also includes a plurality of comparators, each configured to compare the single-ended envelope signal with a corresponding one of a plurality of signal thresholds. According to various embodiments, the differential envelope amplifier includes: an amplification circuit configured to amplify the differential envelope signal; and a common-mode feedback circuit operable to compensate the amplification circuit for common-mode errors caused by a common-mode voltage of the differential envelope signal. According to several embodiments, the amplification circuit includes a first differential input configured to receive the differential envelope signal and a second differential input configured to receive a differential compensation signal from the common-mode feedback circuit. According to several embodiments, the common-mode feedback circuit is configured to provide feedback from the output of the amplification circuit to the second differential input of the amplification circuit. According to various embodiments, the differential envelope amplifier also includes a differential input filter configured to filter the differential envelope signal before amplification by the amplification circuit.

[0018] In several embodiments, each of the plurality of signal thresholds is controllable.

[0019] In some embodiments, the envelope tracker further includes a DC path filter coupled between the DC voltage and the power amplifier supply voltage terminals. According to several embodiments, the DC-DC converter is also configured to generate a DC voltage. According to various embodiments, the DC-DC converter is configured to receive a battery voltage and generate multiple regulated voltages and a DC voltage based on the DC-DC conversion providing the battery voltage. According to several embodiments, the DC path filter includes at least one series inductor and at least one parallel capacitor. According to several embodiments, the DC path through the DC path filter carries at least 75% of the energy supplied to the power amplifier supply voltage terminals.

[0020] In various embodiments, each of the plurality of regulated voltages has a different voltage level.

[0021] In several embodiments, the envelope tracker also includes a plurality of decoupling capacitors, each decoupling capacitor being coupled between ground and a corresponding one of a plurality of regulated voltages.

[0022] In some embodiments, the modulator output filter includes at least one series inductor and at least one parallel capacitor. According to several embodiments, the modulator output filter also includes a DC blocking capacitor connected in series between the modulator output and the power amplifier power supply voltage terminals.

[0023] In some embodiments, this disclosure 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 analog 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 generate a modulator output voltage at the output based on the plurality of regulated voltages and the analog envelope signal; and a modulator output filter coupled between the modulator output and the power amplifier supply voltage. The modulator is configured to generate the modulator output voltage based on comparing the analog envelope signal with a plurality of signal thresholds.

[0024] In various embodiments, the modulator includes a plurality of switches that are selectively activated based on comparing an analog envelope signal with a plurality of signal thresholds. According to several embodiments, each of the plurality of switches is connected between the output of the modulator and a corresponding one of a plurality of regulated voltages.

[0025] In several embodiments, the envelope tracker further includes: a plurality of modulators, each including a modulator; and a plurality of modulator output filters, each of the plurality of modulators being coupled to a power amplifier supply voltage via a corresponding one of the plurality of modulator output filters. According to several embodiments, the effective number of the plurality of modulators is selected based on comparing an analog envelope signal with a plurality of signal thresholds.

[0026] In various embodiments, the modulator is configured to receive analog envelope signals via a mobile industry peripheral interface analog reference interface for envelope tracking.

[0027] In some embodiments, the analog envelope signal is a differential envelope signal. According to several embodiments, the modulator includes a differential envelope amplifier configured to amplify the differential envelope signal to generate a single-ended envelope signal. According to several embodiments, the modulator also includes a plurality of comparators, each configured to compare the single-ended envelope signal with a corresponding one of a plurality of signal thresholds. According to various embodiments, the differential envelope amplifier includes: an amplifier circuit configured to amplify the differential envelope signal; and a common-mode feedback circuit operable to compensate the amplifier circuit for common-mode errors caused by a common-mode voltage of the differential envelope signal. According to several embodiments, the amplifier circuit includes a first differential input configured to receive the differential envelope signal and a second differential input configured to receive a differential compensation signal from the common-mode feedback circuit. According to various embodiments, the common-mode feedback circuit is configured to provide feedback from the output of the amplifier circuit to the second differential input of the amplifier circuit. According to several embodiments, the differential envelope amplifier also includes a differential input filter configured to filter the differential envelope signal before amplification by the amplifier circuit.

[0028] In various embodiments, each of the multiple signal thresholds is controllable.

[0029] In several embodiments, the envelope tracker further includes a DC path filter coupled between the DC voltage and the power amplifier supply voltage. According to several embodiments, the DC-DC converter is also configured to generate a DC voltage. According to some embodiments, the mobile device also includes a battery that outputs a battery voltage, and the DC-DC converter is configured to generate multiple regulated voltages and DC voltages based on the DC-DC conversion providing the battery voltage. According to various embodiments, the DC path filter includes at least one series inductor and at least one parallel capacitor. According to several embodiments, the DC path through the DC path filter carries at least 75% of the energy supplied from the envelope tracker to the power amplifier.

[0030] In various embodiments, each of the plurality of regulated voltages has a different voltage level.

[0031] In some embodiments, the envelope tracker further includes a plurality of decoupling capacitors, each decoupling capacitor being coupled between ground and a corresponding one of a plurality of regulated voltages.

[0032] In several embodiments, the modulator output filter includes at least one series inductor and at least one parallel capacitor. According to several embodiments, the modulator output filter also includes a DC blocking capacitor connected in series between the modulator output voltage and the power amplifier supply voltage. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a mobile device according to one embodiment.

[0034] Figure 2 This is a schematic diagram of one embodiment of an envelope tracking system for a power amplifier.

[0035] Figure 3A This is a schematic diagram of another embodiment of an envelope tracking system for a power amplifier.

[0036] Figure 3B This is a schematic diagram of another embodiment of an envelope tracking system for a power amplifier.

[0037] Figure 3C This is a schematic diagram of another embodiment of an envelope tracking system for a power amplifier.

[0038] Figure 4 This is a schematic diagram of another embodiment of an envelope tracking system for a power amplifier.

[0039] Figure 5 This is a schematic diagram of another embodiment of an envelope tracking system for a power amplifier.

[0040] Figure 6A This is a schematic diagram of one embodiment of a differential envelope amplifier used in an envelope tracking system.

[0041] Figure 6B This is a schematic diagram of another embodiment of a differential envelope amplifier used in an envelope tracking system.

[0042] Figure 7 This is a schematic diagram of one embodiment of an amplifier circuit used in a differential envelope amplifier.

[0043] Figure 8 This is an example graph of differential analog envelope signal voltage versus time.

[0044] Figure 9 This is a schematic diagram of one embodiment of a comparator circuit for a multi-level power supply (MLS) modulator.

[0045] Figure 10 It is used for Figure 9 A schematic diagram of an embodiment of a comparator circuit.

[0046] Figure 11 This is a schematic diagram of a mobile device according to another embodiment.

[0047] Figure 12 This is a schematic diagram of one embodiment of a communication system for transmitting radio frequency (RF) signals.

[0048] Figure 13 This is a schematic diagram of an MLS modulation system according to one embodiment.

[0049] Figure 14 This is a schematic diagram of an MLS DC-DC converter according to one embodiment.

[0050] Figure 15 This is a schematic diagram illustrating an example of timing for MLS DC-DC conversion.

[0051] Figure 16 This is a schematic diagram of an example of MLS envelope tracking for continuous wave signals. Detailed Implementation

[0052] The following detailed description of certain embodiments presents various descriptions of particular embodiments. However, the innovations described herein can be embodied in a variety of different ways, for example, as defined and covered by the claims. In this specification, 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 shown in the figures are not necessarily drawn to scale. Furthermore, it should be understood that some embodiments may include more elements than a subset of those shown in and / or shown in the figures. Additionally, some embodiments may incorporate any suitable combination of features from two or more figures.

[0053] Envelope tracking is a technique used to improve the power-added efficiency (PAE) of a power amplifier by efficiently 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 be increased. Similarly, when the envelope of the RF signal decreases, the voltage supplied to the power amplifier can be decreased to reduce power consumption.

[0054] This document provides a multi-stage envelope tracker with an analog interface. 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: a multi-level supply (MLS) DC-DC converter that outputs multiple regulated voltages; an MLS modulator that controls the selection of regulated voltages over time based on an analog 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.

[0055] An MLS modulator processes an analog envelope signal to control modulation operations. For example, in some implementations, an MLS modulator includes two or more comparators for comparing the signal level of the analog envelope signal with different threshold levels. Furthermore, the output signals of the comparators are used to control the selection of modulator switches, thereby controlling modulation.

[0056] In some implementations, the analog envelope signal is received via a Mobile Industry Peripheral Interface (MIPI) analog reference interface for envelope tracking (eTrak). Furthermore, an MLS modulator processes the analog envelope signal to control its operation. Therefore, the teachings herein can be used to repurpose the MIPI eTrak interface for multi-level envelope tracking.

[0057] To enhance the granularity of modulation control, in some implementations, the envelope tracking system includes two or more modulators and two or more corresponding modulator output filters, which operate in parallel to generate the power amplifier supply voltage based on the analog envelope signal and the regulated voltage. Including multiple modulators provides finer quantization resolution. For example, compared to an implementation with a single modulator and a single modulator output filter, any number of modulators can be activated at a given time to provide greater control over the power amplifier supply voltage.

[0058] In some implementations, the envelope tracking system also includes a DC path filter coupled between the DC voltage and the power amplifier supply voltage. Improved efficiency of the envelope tracking system can be achieved by including a DC path via the DC path filter and a separate AC path via the modulator output filter.

[0059] For example, a low-frequency current, such as DC current, can be supplied via a DC path filter (e.g., via a filter inductor), thereby relaxing the size and / or DC resistance constraints of the modulator switches. Consequently, lower switching losses can be achieved in the AC path, thus improving overall system efficiency. In one example, the DC path carries at least 75% of the energy supplied to the power amplifier by the envelope tracking system.

[0060] In some implementations, the DC voltage is a regulated voltage from a DC-DC converter. For example, an MLS DC-DC converter can also be used to generate a DC voltage. In such implementations, the voltage level of the DC voltage may be the same as or different from the voltage level of one of the regulated voltages supplied to the MLS modulator.

[0061] 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.

[0062] Although one embodiment of a mobile device has been shown, the teachings of this article are applicable to mobile devices implemented in a variety of ways. Therefore, other implementations are also possible.

[0063] 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 diplexer 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. Additionally, 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.

[0064] While one embodiment of the front-end circuitry has been 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., diplexing or tripling), or some combination thereof.

[0065] 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.

[0066] like Figure 1 As shown, the MLS envelope tracker 9 is used to generate one or more power amplifier supply voltages for the power amplifier used in the mobile device 70 to amplify the RF signal used 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 second power amplifier 22 PA2 Although an example of the MLS envelope tracker 9 generating two power amplifier supply voltages has been shown, the MLS envelope tracker 9 can generate more or fewer power amplifier supply voltages.

[0067] MLS envelope tracker 9 controls the power supply voltage V of the first power amplifier. PA1 To track the envelope of the first RF signal amplified by the first power amplifier 21. Additionally, 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 the second RF signal amplified by the second power amplifier 22. In some embodiments, the MLS envelope tracker 9 receives digital signals from the baseband modem 11. For example, the MLS envelope tracker 9 may receive digital signals indicating the envelope of the first RF signal and the envelope of the second RF signal.

[0068] Battery 8 can be any suitable battery used in 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.

[0069] Transceiver 10 generates RF signals for transmission and processes input RF signals received from main antenna 1 and diversity antenna 2. It should be understood that various functions associated with the transmission and reception of RF signals can be implemented through... Figure 1 The RF signal is typically represented as one or more components of transceiver 10. In one example, separate components (e.g., separate circuits or chips) may be provided to handle certain types of RF signals.

[0070] The baseband modem 11 provides a digital representation of the transmitted signal to the transceiver 10, which processes the transmitted signal 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.

[0071] like Figure 1As shown, baseband modem 11 is coupled to application processor 12, which provides primary application processing in mobile device 70. Application processor 12 can provide a variety of functions, such as providing system capabilities suitable for supporting applications including but not limited to memory management, graphics processing, and / or multimedia decoding.

[0072] 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 one or more multi-level envelope trackers implemented in accordance with the teachings of this document.

[0073] Figure 2-5 Schematic diagrams depict various embodiments of envelope tracking systems for power amplifiers. However, the teachings herein apply to envelope trackers implemented in a variety of ways. Therefore, other implementations are possible.

[0074] Figure 2 This is a schematic diagram of one embodiment of an envelope tracking system 100 for a power amplifier 71. In this embodiment, the envelope tracking system 100 includes an MLS DC-DC converter 72, a DC path filter 73, an MLS modulator 81, and a modulator output filter 91 used as an AC path filter. The MLS DC-DC converter 72 is also referred to herein as a switching regulator.

[0075] Power amplifier 71 amplifies the RF input signal. IN To generate RF output signal RF OUT The MLS modulator 81 receives the signal relative to the RF input signal RF. IN The simulated envelope signal (ENVELOPE) represents the envelope variation. In some implementations, the simulated envelope signal corresponds to the envelope signal received from the MIPI eTrak interface. However, other implementations are also possible.

[0076] In the illustrated embodiment, the MLS DC-DC converter 72 receives the battery voltage V. BATT It also provides DC-DC conversion to generate various regulated voltages V at different voltage levels. MLSa V MLSb V MLSc ...V MLSn Although an example of four MLS voltages has been described, as shown in the ellipse, the MLS DC-DC converter 72 can produce more or less MLS voltage. In this embodiment, the MLS DC-DC converter 72 also regulates the battery voltage V. BATT To generate DC voltage V DC DC voltage V DC It can have the same voltage as the adjustable voltage V MLSa VMLSb V MLSc ...V MLSn One is the same or different voltage level.

[0077] MLS modulator 81 receives regulated voltage V MLSa V MLSb V MLSc ...V MLSn The modulator output voltage is output to AC path filter 91, along with the envelope signal. In some embodiments, the MLS modulator 81 selects an appropriate regulating voltage over time based on the analog envelope signal to control the output voltage. For example, the MLS modulator 81 may include a set of switches for selectively connecting the regulating voltage V based on the signal level of the envelope signal. MLSa V MLSb V MLSc V MLSn To the output of the modulator.

[0078] In some implementations, the MLS modulator 81 generates a modulator output voltage based on comparing an analog envelope signal with two or more signal thresholds. For example, the MLS modulator 81 may include two or more comparators that compare the analog envelope signal with different signal thresholds. Furthermore, the MLS modulator 81 may include multiple switches, each connected between the output of the MLS modulator 81 and a corresponding regulated voltage, and these switches may be activated individually based on the comparisons.

[0079] DC path filter 73 and modulator output filter 91 respectively filter the DC voltage V from MLS DC-DC converter 72. DC The output of the MLS modulator 81 is filtered to generate the power amplifier supply voltage V for the power amplifier 71. PA .

[0080] Enhanced efficiency of the envelope tracking system 100 can be achieved by including a DC path via DC path filter 73 and a separate AC path via modulator output filter 91. For example, low-frequency current (including but not limited to DC current) can be provided via DC path filter 73, thereby relaxing the size and / or DC resistance limitations of the MLS modulator switches.

[0081] Therefore, lower switching losses in the AC path can be achieved, thereby improving overall system efficiency. In one example, the DC path delivers at least 75% of the energy provided by the envelope tracking system 100 to the power amplifier 71.

[0082] Figure 3AThis is a schematic diagram of another embodiment of the envelope tracking system 140 for power amplifier 101. The envelope tracking system 140 includes an envelope tracking integrated circuit (IC) 102, a DC path filter 103, a modulator output filter 104 (used as an AC path filter in this embodiment), a DAC circuit 105, an envelope filter 106, first to fourth decoupling capacitors 111-114, and an inductor 117, respectively.

[0083] although Figure 3A The document illustrates one embodiment of an envelope tracking system, but the teachings herein apply to envelope tracking systems implemented in various ways. Therefore, other implementations are possible.

[0084] 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 various pins or pads for providing a variety of functions, such as receiving battery voltage (V). BATT ), communicates via Serial Peripheral Interface (SPI), and outputs DC voltage V. DC Receive differential analog envelope signal (ENV) _p ENV _n It is connected to decoupling capacitors 111-114 and to inductor 117. The envelope tracking IC is also referred to herein as an envelope tracking semiconductor chip or chip.

[0085] 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 different voltage levels of regulated MLS voltage and regulated DC voltage V. DC However, the MLS switching circuit 121 can be implemented to output more or less regulated voltage.

[0086] As shown in Figure 3A, the MLS switching circuit 121 is controlled by a digital control circuit 122. The digital control circuit 122 provides programmability to the MLS switching circuit 121, including but not limited to controlling one or more regulated voltages output by the MLS switching circuit 121. 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 based on data received via the SPI bus and / or other chip interfaces.

[0087] The baseband MLS modulator 123 includes an AC path 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 regulated MLS voltage and the modulator output filter. Additionally, the modulator's switch is selectively opened or closed by the modulator controller 124 based on the envelope signal.

[0088] In some embodiments, the modulator control circuit 124 includes a differential envelope amplifier for converting the differential analog envelope signal into a single-ended envelope signal, and two or more comparators for comparing the single-ended analog envelope signal with different signal thresholds. Additionally, the modulator controller 124 controls the activation of the switching on / off state of the MLS modulator 123 based on the comparison results.

[0089] In the illustrated embodiment, the DC path filter 103 includes a parallel capacitor 127 and a series inductor 128. Additionally, the modulator output filter 104 includes a first series inductor 131, a second series inductor 132, a first parallel capacitor 135, and a second parallel capacitor 136. Although in Figure 3A The document describes an example implementation of a DC path filter and a modulator output filter 104, but the teachings herein apply to DC path filters and AC path filters implemented in various ways. Therefore, other implementations of the filter can be used in accordance with the teachings herein.

[0090] 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 135 and the second parallel capacitor 136 are controllable. Although two examples of controllable filter components are shown, other filter components may be additionally or alternatively implemented as controllable.

[0091] Figure 3B This is a schematic diagram of another embodiment of the envelope tracking system 150 for power amplifier 101. Figure 3B The envelope tracking system 150 is similar to Figure 3A The envelope tracking system 140 differs from the envelope tracking system 150 in that it includes a different implementation of the modulator output filter 144.

[0092] For example, compared to the modulator output filter 104 in Figure 3A, Figure 3B The modulator output filter 144 also includes a DC blocking capacitor 138 for preventing low-frequency current from passing through the modulator output filter 144. In the illustrated embodiment, the DC blocking capacitor 138 is coupled to the output of the modulator output filter 144.

[0093] By including the DC blocking capacitor 138, lower switching losses can be achieved in the AC path, thereby improving overall system efficiency. For example, including the DC blocking capacitor 138 can help increase the percentage of energy carried by the DC path through the DC path filter 103 relative to the energy carried by the AC path through the modulator output filter 144. In one example, the DC path through the DC path filter 103 delivers at least 75% of the energy provided by the envelope tracking system 150 to the power amplifier 101.

[0094] Figure 3C This is a schematic diagram of another embodiment of the envelope tracking system 160 for power amplifier 101. Figure 3C The envelope tracking system 160 is similar to Figure 3B The envelope tracking system 150 differs from Figure 160 in that it includes a different implementation of the modulator output filter 154.

[0095] For example, with Figure 3B Compared to the modulator output filter 144, Figure 3C The modulator output filter 154 includes a DC blocking capacitor 138 coupled to the filter input. The DC blocking capacitor can be included in various locations within the modulator output filter, including, for example, at the input, the output, or along the signal path between the input and the output.

[0096] Figure 4 This is a schematic diagram of another embodiment of an envelope tracking system 170 for a power amplifier. The envelope tracking system 170 includes an MLS DC-DC converter 72, a DC path filter 73, MLS modulators 81a, 81b...81n, and modulator output filters 91a, 91b...91n.

[0097] Figure 4 The envelope tracking system 170 is similar to Figure 2 The envelope tracking system 100 differs from the envelope tracking system 170 in that it includes multiple modulators and multiple modulator output filters that operate in parallel to each other to generate the power amplifier power supply voltage based on the analog envelope signal and the regulated voltage.

[0098] Including multiple modulators can provide finer quantization resolution. For example, any number of modulators (0, 1, 2, etc.) can be activated at a given time to provide greater control over the power amplifier supply voltage.

[0099] Figure 5 This is a schematic diagram of another embodiment of an envelope tracking system 180 for a power amplifier. Figure 5The envelope tracking system 180 includes an envelope tracking IC 172, a DC path filter 103, a first modulator output filter 144a, a second modulator output filter 144b, a DAC circuit 105, an envelope filter 106, first to fourth decoupling capacitors 111-114, and an inductor 117, respectively. The envelope tracking IC 172 includes an MLS switching circuit 121, a digital control circuit 122, a first baseband MLS modulator 123a, a second baseband MLS modulator 123b, and a modulator control circuit 124. Although an example with two baseband MLS modulators is shown, more or fewer baseband MLS modulators may be included.

[0100] Modulator control circuit 124 controls MLS modulators 123a and 123b based on differential analog envelope signals ENV_p and ENV_n. Modulator control circuit 124 can control whether one or both of the MLS modulators 123a and 123b are activated, and the specific modulator switches in each modulator are turned on or off. Including two or more MLS modulators can enhance quantization and provide greater control over the generation of the power amplifier supply voltage VPA.

[0101] In some embodiments, the modulator control circuit 124 includes a differential envelope amplifier for converting the differential analog envelope signal into a single-ended envelope signal, and two or more comparators for comparing the single-ended analog envelope signal with different signal thresholds. Additionally, the modulator controller 124 controls the activation of the switches of the MLS modulators 123a and 123b based on the comparison results.

[0102] Figure 6A This is a schematic diagram of one embodiment of a differential envelope amplifier 210 for an envelope tracking system. The differential envelope amplifier 210 includes an amplifier circuit 201, a common-mode feedback circuit 202, and a differential input filter 203.

[0103] Figure 6A The differential envelope amplifier 210 illustrates one embodiment of a differential envelope amplifier. In some implementations, the differential envelope amplifier is included in an envelope tracking interface to convert the differential envelope signal into a single-ended envelope signal and / or provide compensation for common-mode errors. For example, a differential envelope tracker may be included in the control circuitry of a modulator. Although only one example of a differential envelope amplifier is shown, differential envelope amplifiers can be implemented in various ways.

[0104] The differential input filter 203 receives the differential analog envelope signals ENV_p and ENV_n, and filters the differential analog envelope signals to generate a filtered differential analog envelope signal.

[0105] Amplifier circuit 201 includes a first differential input that receives a filtered differential analog envelope signal from differential input filter 203 and a second differential input that receives a differential compensation signal from common-mode feedback circuit 202. Amplifier circuit 201 includes an output that generates a single-ended analog envelope signal ENV.

[0106] like Figure 6A As shown, the common-mode feedback circuit 202 is connected between the output of amplifier circuit 201 and the second differential input of amplifier circuit 201. In this example, the common-mode feedback circuit 202 provides a single-ended to differential signal conversion.

[0107] The common-mode feedback circuit 202 provides feedback that compensates for the error caused by the common-mode voltage of the differential analog envelope signals ENV_p and ENV_n in the amplifier circuit 201.

[0108] Figure 6B This is a schematic diagram of one embodiment of a differential envelope amplifier 240 for an envelope tracking system. The differential envelope amplifier 240 includes an amplifier circuit 211, a common-mode feedback circuit 212, and a differential input filter 213.

[0109] Figure 6B The differential envelope amplifier 240 is similar to Figure 6A The differential envelope amplifier 210 differs from the differential envelope amplifier 240 in that it includes a specific implementation of the circuit. Although an example of the circuit has been shown, differential envelope amplifiers can be implemented in other ways.

[0110] In the illustrated embodiment, amplifier circuit 211 includes a first differential input, a second differential input, and an output. The first differential input is a voltage input associated with a first transconductance Gm_IN, and the second differential input is a voltage input associated with a second transconductance Gm_FBK. In some embodiments, the transconductance of Gm_IN is greater than the transconductance of Gm_FBK.

[0111] Continue to refer to Figure 6B The common-mode feedback circuit 212 includes a first resistor 221 and a second resistor 222, which serve as the generator for the voltage divider V. DIV The amplifier operates using a voltage divider. A first resistor 221 and a second resistor 222 are connected in series between the output of the amplifier circuit 211 and a reference voltage, such as ground. The common-mode feedback circuit 212 includes a capacitor 224 connected in parallel with the first resistor 221. The common-mode feedback circuit 212 also includes a third resistor 223 and a current source 225 connected in series between the power supply voltage and ground. The second differential input of the amplifier circuit 211 will cross the voltage V across the third resistor 223. R The voltage V generated by the first and second resistors 221 and 222 DIVA comparison is made. In some implementations, the current source 225 is controllable (e.g., variable and / or programmable) to control the common-mode settings of the common-mode feedback circuit 212.

[0112] The common-mode feedback circuit 212 operates to provide feedback on the output DC bias point or level of the control amplifier circuit 211, thereby reducing or eliminating the influence of the common-mode voltage of the differential analog envelope signals ENV_P and ENV_n.

[0113] In the illustrated embodiment, the differential input filter 213 includes a first filter resistor 231, a second filter resistor 232, and a filter capacitor 233. The differential input filter 213 provides low-pass filtering for the differential analog envelope signals ENV_p and ENV_n, and provides the filtered differential analog envelope signals to the first differential input of the amplifier circuit 211.

[0114] Figure 7 It is used for Figure 6A and 6B A schematic diagram of one embodiment of the differential envelope amplifier circuit 400. Although an example of a suitable amplifier circuit is shown, the differential envelope amplifier may include amplifier circuits implemented in a variety of ways.

[0115] like Figure 7 As shown, the differential amplifier circuit 400 includes amplification of the first differential input IN. p IN n The first pair of p-type field-effect transistors (PFETs) 301-302. The first pair of PFETs 301-302 is supplied by the first pair of current sources 321-322 (each providing a current I in this example). BIAS The differential amplifier circuit 400 includes a first resistor 331 of resistance R, which is used to couple the source of PFET 301 to the source of PFET 302. The differential amplifier circuit 400 also includes a second pair of PFETs 303-304, which are used to amplify the second differential input V corresponding to the differential common-mode compensation signal. INp_fd V INn_fd The second pair of PFETs 303-304 are supplied by the second pair of current sources 323-324 (which also provide current I in this example). BIAS It is biased and includes a second resistor 332 (which also has a resistor R in this example) for coupling the source of PFET 303 to the source of PFET 304.

[0116] The current from the first pair of PFETs 301-302 and the second pair of PFETs 303-304 is combined using current sources 325-326, cascode n-type field-effect transistors (NFETs) 311-312, and load PFETs 313-314. In this example, the gate of the cascode NFETs 311-312 is biased by a voltage V. BIAS control.

[0117] The amplifier circuit 400 also includes a push-pull output stage, which comprises an output NFET 317, an output PFET 318, a current source 327, and a class AB bias circuit 328. For example... Figure 7 As shown, current source 327 provides current I. BIAS_AB The bias circuit 328 is biased to the class AB bias circuit, which biases the output NFET 317 and the output PFET 318 to provide enhanced bandwidth.

[0118] Figure 8 This is a graph illustrating an example of differential analog envelope signal voltage versus time. (See figure.) Figure 8 As shown, the non-inverting envelope signal ENV_p and the inverting envelope signal ENV_n are used as differential analog envelope operations. By using differential signals, common-mode noise (V_cm) can be suppressed.

[0119] In one example, the differential analog envelope signal corresponds to the MIP eTrak envelope signal, such as a 1.2V differential envelope signal with a 1.5V peak-to-peak maximum input swing or a 1.8V differential envelope signal with a 2V peak-to-peak maximum input swing.

[0120] Figure 9 This is a schematic diagram of one embodiment of a comparator circuit 610 for an MFS modulator. The comparator circuit 610 includes comparators 601a, 601b...601m, resistors 603a, 603b...603m, and controllable current sources 602a, 602b...602m.

[0121] Although an example with three comparators and corresponding circuitry is shown, more or fewer comparators, as indicated by the ellipse, may be included. Furthermore, while one implementation of the comparator circuitry for an MFS modulator is shown, other implementations of the comparator circuitry may be used in accordance with the teachings of this document.

[0122] Comparator circuit 610 receives (e.g., from a differential envelope amplifier, including but not limited to) Figure 6A Differential envelope amplifier 210 or Figure 6BThe differential envelope amplifier 240 uses a single-ended analog envelope signal ENV to generate comparator output signals Lvla, Lvlb, ..., Lvlm.

[0123] The comparator output signals Lvla, Lvlb, ..., Lvlm are generated based on comparing the single-ended envelope signal ENV with different signal thresholds. For example, although comparators 601a, 601b, ..., 601m all receive a common reference voltage V... ref However, the individual threshold values ​​of comparators 601a, 601b, ... 601m are controlled by controllable current sources 602a, 602b, ... 602m respectively. For example, the current amplitudes from controllable current sources 602a, 602b, ... 602m control the voltage drop across resistors 603a, 603b, ... 603m and the corresponding signal threshold values ​​used for comparison, respectively.

[0124] In the illustrated embodiment, the n-bit digital control signal LKa <l:n>、LCb <l:n>……LKm <l:n>These are the levels of signal thresholds used to control comparators 601a, 601b...601m, respectively. In some implementations, the digital control signals are controlled based on data received via an interface such as an SPI bus. Although an example of signal threshold control has been shown, the teachings of this document apply to signal threshold control implemented in other ways.

[0125] In some implementations, the comparator output signals Lvla, Lvlb...Lvlm are used to control the individual switches of the modulator and / or the selective activation of multiple active modulators in a multi-modulator implementation.

[0126] Figure 10 It is used for Figure 9 A schematic diagram of an embodiment of comparator 720 of comparator circuit 610 is shown. Although one example of a suitable comparator is shown, an MLS modulator may include comparators implemented in a variety of ways.

[0127] Comparator 720 includes a pair of input NFETs 701a-701b, a pair of bias NFETs 702a-702b, a first pair of load PFETs 703a-703b, a second pair of load PFETs 704a-704b, a first pair of current source PFETs 705a-705b, a first pair of mirror NFETs 706a-706b, a second pair of current source PFETs 707a-707b, a second pair of mirror NFETs 708a-708b, a pair of current source NFETs 710a-710b, a third pair of load PFETs 709a-709b, a pair of output PFETs 711a-711b, and a pair of output NFETs 712a-712b. In some embodiments, the bias NFET 702b is larger in size than the bias NFET 702a (e.g., has a larger device width), but is implemented with a matched transistor layout.

[0128] In the illustrated embodiment, comparator 720 receives the input voltage V. in and reference voltage V ref It outputs differential comparison signals OUT+ and OUT- to indicate the comparison result. The comparator 720 is controlled by current I... BIAS It is biased and receives the power supply voltage VDD and the ground voltage GND. Although the comparison signal is implemented differentially in this example, either the signal component of the differential comparison signal OUT+ or OUT- can be used as a single-ended comparison signal.

[0129] Figure 11 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.

[0130] The mobile device 800 can be used to communicate using a variety of communication technologies, including but not limited to 2G, 3G, 4G (including LTE, LTE-Advanced and LTE-Advanced Pro), 5G, WLAN (e.g., Wi-Fi), WPAN (e.g., Bluetooth and ZigBee), WMAN (e.g., WiMax) and / or GPS technology.

[0131] Transceiver 802 generates RF signals for transmission and processes input 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 one or more [unclear - possibly a specific function or interface]. Figure 11 The components represented together as transceiver 802 are implemented. In one example, separate components (e.g., separate circuits or chips) may be provided to handle certain types of RF signals.

[0132] 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 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.

[0133] For example, the front-end system 803 can provide a variety of functionalities, including but 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 different transmit and receive modes, signal duplexing, signal multiplexing (e.g., dual-signal or triple-signal), or some combination thereof.

[0134] In some implementations, the mobile device 800 supports carrier aggregation, providing flexibility to increase peak data rates. Carrier aggregation can be used for both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) and can be used to aggregate multiple carriers or channels. Carrier aggregation includes the contiguous aggregation of consecutive carriers within the same operating frequency band. Carrier aggregation can also be non-contiguous and can include carriers with separated frequencies in a common frequency band or different frequency bands.

[0135] Antenna 804 may include antennas for various communication types. For example, antenna 804 may include antennas associated with transmitting and / or receiving signals associated with various frequencies and communication standards.

[0136] In some implementations, antenna 804 supports MIMO communication and / or handshake diversity communication. For example, MIMO communication uses multiple antennas to transmit multiple data streams on a single radio frequency channel. Due to spatial multiplexing differences in the radio environment, MIMO communication benefits from higher signal-to-noise ratios, improved coding, and / or reduced signal interference. Handshake 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 a set of antennas based on multiple factors such as observed bit error rate and / or signal strength indicators.

[0137] In some embodiments, the mobile device 800 may operate using beamforming. For example, the front-end system 803 may include a phase shifter having a variable phase controlled by the transceiver 802. Additionally, the phase shifter is controlled to provide beamforming and directivity for transmitting and / or receiving signals using the antenna 804. For example, in the context 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 generate a converged transmitted signal exhibiting beam-like quality that propagates with greater signal strength 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.

[0138] Baseband system 801 is coupled to user interface 807 to facilitate the processing of various user inputs and outputs (I / O), such as voice and data. Baseband system 801 provides a digital representation of the transmitted signal to transceiver 802, which processes it to generate an RF signal for transmission. Baseband system 801 also processes a digital representation of the received signal provided by transceiver 802. Figure 11 As shown, the baseband system 801 is coupled to a memory 806 that facilitates operation of the mobile device 800.

[0139] 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.

[0140] 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 tracker 860 implemented according to one or more features of this disclosure.

[0141] like Figure 11 As shown, the power management system 805 receives battery voltage from the battery 808. The battery 808 can be any suitable battery used in the mobile device 800, including, for example, a lithium-ion battery.

[0142] Figure 12 This 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 pre-distortion (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.

[0143] Figure 12 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 disclosure. However, the teachings herein apply to RF systems implemented in a variety of ways.

[0144] 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 having 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.

[0145] Signal delay circuit 908 provides adjustable delays to the I and Q signals to assist in controlling the differential analog envelope signals ENV_p and ENV_n provided to the MLS envelope tracker 902 and the RF signal RF provided to the power amplifier 903. IN The relative alignment between them. The amount of delay provided by the signal delay circuit 908 is controlled based on the amount of intermodulation in adjacent frequency bands detected by the intermodulation detection circuit 912.

[0146] 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 amount of intermodulation detected by the intermodulation detection circuit 912. The DPD circuit 909 is used to reduce the distortion of the power amplifier 903 and / or increase the efficiency of the power amplifier 903.

[0147] The I / Q modulator 910 receives digitally predistorted I and Q signals, which are processed to generate an RF signal. IN For example, the I / Q modulator 910 may include a DAC configured to convert digitally 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 combiner. In some embodiments, the I / Q modulator 910 may include one or more filters configured to filter the frequency content of the signal processed therein.

[0148] Envelope delay circuit 921 delays the I and Q signals from baseband processor 907. Additionally, CORDIC circuit 922 processes the delayed I and Q signals to generate a representation of the RF signal RF. IN The digital envelope signal of the envelope. Although Figure 12 The implementation using the CORDIC circuit 922 is shown, but the envelope signal can also be obtained in other ways.

[0149] 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.

[0150] In the illustrated embodiment, the shaped envelope signal is a digital signal converted into a differential analog envelope signal by the DAC 924. Additionally, the differential analog envelope signal is filtered by a reconstruction filter 925 to generate differential envelope signals ENV_p and ENV_n suitable for use by the differential envelope amplifier of the MLS envelope tracker 902. In some implementations, the reconstruction filter 925 includes a differential low-pass filter.

[0151] Continue to refer to Figure 12 The MLS envelope tracker 902 receives the differential analog envelope signal from the reconstruction filter 925 and the battery voltage V from the battery 901. BATT Differential analog envelope signals ENV_p and ENV_n are used to generate a RF signal that follows the voltage power amplifier 903. IN The power amplifier supply voltage V varies with the envelope. CC_PA In this example, power amplifier 903 receives RF signal RF from I / Q modulator 910. IN The amplified RF signal RFOUT is provided to the antenna 906 via the duplex and switching circuit 905.

[0152] A directional coupler 904 is located between the output of the power amplifier 903 and the input of the duplex and switching circuit 905, thereby allowing measurement of the output power of the power amplifier 903, excluding the insertion loss of the duplex and switching circuit. The sensed output signal from the directional coupler 904 is provided to an 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.

[0153] Intermodulation detection circuit 912 determines the intermodulation product 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 provided by DPD circuit 909 and / or signal delay circuit 908 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.

[0154] By incorporating feedback paths from the output of 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 assist in providing power control, compensating for transmitter impairments, and / or performing DPD.

[0155] 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.

[0156] Figure 13 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.

[0157] Figure 13 The MLS modulation system 1050 illustrates one embodiment of an MLS modulator circuit suitable for integration into a multi-stage envelope tracker. However, other implementations of the MLS modulator circuit can be included in a multi-stage envelope tracker implemented according to the teachings herein.

[0158] The MLS DC-DC converter 1025 is based on providing battery voltage V. BATT DC-DC conversion to generate the first regulated voltage V MLS1、 Second regulating voltage V MLS2 and the third regulating voltage V MLS3 Although an example with three regulated voltages is shown, the MLS DC-DC converter 1025 can produce more or fewer regulated voltages. In some embodiments, at least a portion of the regulated voltage is relative to the battery voltage V. BATT The voltage is increased. Additionally or alternatively, one or more regulating voltages are lower than the battery voltage V. BATT The voltage drop of the voltage.

[0159] Decoupling capacitor bank 1030 assists in stabilizing the regulated voltage generated by MLS DC-DC converter 1025. For example, Figure 13 The decoupling capacitor bank 1030 includes a first regulating voltage V MLS1 The first decoupling capacitor 1031 is used for the second regulating voltage V. MLS2 The second decoupling capacitor 1032 and the third regulating voltage V MLS3 The third decoupling capacitor is 1033.

[0160] Continue to refer to Figure 13 The modulator switch group 1027 includes connections to the output of the modulator (MOD). 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 located between the two switches. The modulator controller 1020 operates to selectively open or close switches 1041-1043, thereby controlling the output of the modulator.

[0161] Figure 14 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 also includes control circuitry for opening and closing the switches to provide regulation. Figure 14 (Not shown in the image).

[0162] Figure 14 The MLS DC-DC converter 1073 illustrates an implementation of an MLS DC-DC converter suitable for incorporation into a multi-stage envelope tracker. However, other implementations of the MLS DC-DC converter may be included in a multi-stage envelope tracker implemented according to the teachings herein.

[0163] In the illustrated embodiment, the first switch S1 includes a component electrically connected to the battery voltage V. BATT The first terminal is electrically connected to the first terminal of the second switch S2 and the second terminal of the first terminal of the inductor 1075. The second switch S2 also includes a first or ground power supply V. GND The second end. Although Figure 14 The illustration shows a configuration of a DC-DC converter powered using ground and battery voltage, but the teachings herein apply to DC-DC converters powered using any suitable power source. Inductor 1075 also includes a second terminal electrically connected to the first terminal of each of the third through sixth switches S3-S6. The third switch S3 also includes an electrical connection to ground power supply V. GND The second terminal. Each of the fourth, fifth, and sixth switches S4-S6 includes components configured to generate the first, second, and third regulated voltages V, respectively. MLS1 V MLS2 and V MLS3 The second end.

[0164] 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.

[0165] In the illustrated embodiment, the MLS DC-DC converter 1073 operates as a buck-boost converter, 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 step-down voltage can be adjusted. However, other implementation methods are also possible.

[0166] Figure 15 This is a schematic diagram illustrating an example of timing for MLS DC-DC conversion. As shown in Figure 15, the width of the regulation period can be used to control the voltage level of the regulated voltage generated by the MLS DC-DC conversion. 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, the non-overlapping period tovlp can be used to avoid crossbar current between different voltage levels.

[0167] 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.

[0168] The regulated voltage generated by the MLS DC-DC converter can be selectively supplied to the modulator output filter by the modulator. In the example shown, 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.

[0169] Figure 16 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 the MLS voltage level applicable to the signal is shown.

[0170] in conclusion

[0171] The embodiments described above have provided examples relevant to mobile devices. However, the principles and advantages of these embodiments can be applied to any other system or device that requires envelope tracking.

[0172] Unless the context explicitly requires otherwise, throughout the specification and claims, the terms "comprising," "including," etc., shall be interpreted in an inclusive rather than exclusive or exhaustive sense; that is, in the sense of "including but not limited to." As generally used herein, the term "coupled" refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Similarly, as generally used herein, the term "connected" refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Furthermore, when used in this application, the terms "this," "above," "below," and similar terms shall refer to the entire application and not to any particular part of the application. Where the context permits, singular or plural terms used in the foregoing details may also include the plural or singular, respectively. The term "or" refers to a list of two or more items, and this term encompasses all of the following interpretations of the term: any item in the list, all items in the list, and any combination of items in the list.

[0173] Furthermore, the conditional language used herein, such as "may," "can," "possibly," "possibly," "example," "for example," "such as," etc., unless otherwise specifically stated or otherwise understood as in the context in which they are used, is generally intended to convey that certain embodiments include certain features, elements, and / or states, while other embodiments do not. 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 necessarily include logic for determining whether such features, elements, and / or states are included or will be performed in any particular embodiment, with or without author input or prompting.

[0174] The foregoing detailed description of various embodiments of the present invention is not intended to be exhaustive or to limit the invention to the precise forms disclosed above. Although specific embodiments and examples of the invention have been described above for illustrative purposes, those skilled in the art will recognize that various equivalent modifications can be made within the scope of the invention. For example, while processes or block diagrams are presented in a given order, alternative embodiments may execute routines with steps, or employ systems with block diagrams in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and / or modified. Each of these processes or block diagrams can be implemented in various different ways. Furthermore, while processes or block diagrams are sometimes shown as being executed sequentially, these processes or block diagrams may alternatively be executed in parallel, or may be executed at different times.

[0175] The teachings of the invention provided herein can be applied to other systems, not necessarily those described above. Elements and actions of the various embodiments described above can be combined to provide further embodiments.

[0176] While 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 disclosure. In fact, the novel methods and systems described herein may be embodied in many other forms; furthermore, various omissions, substitutions, and changes may be made to the form of the methods and systems described herein without departing from the spirit of this disclosure. The appended claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of this disclosure.< / l:n> < / l:n> < / l:n>

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; and An envelope tracker configured to generate the power amplifier supply voltage based on an analog envelope signal corresponding to the envelope of the radio frequency signal, the envelope tracker comprising: a DC-DC converter configured to output a plurality of regulated voltages; a modulator configured to generate a modulator output voltage at the output based on the plurality of regulated voltages and the analog envelope signal; a modulator output filter coupled between the output of the modulator and the power amplifier supply voltage; and a DC path filter coupled between a DC voltage from the DC-DC converter and the power amplifier supply voltage, the modulator being configured to generate the modulator output voltage based on comparing the analog envelope signal with a plurality of signal thresholds, the DC path filter and the modulator output filter respectively filtering the DC voltage from the DC-DC converter and the modulator output voltage generated by the modulator, thereby generating the power amplifier supply voltage for the power amplifier.

2. The envelope tracking system as described in claim 1, wherein, The modulator includes a plurality of switches that are selectively activated based on comparing the analog envelope signal with a plurality of signal thresholds.

3. The envelope tracking system as described in claim 1, wherein, The envelope tracker further includes: a plurality of modulators including modulators and a plurality of modulator output filters including modulator output filters, each of the plurality of modulators being coupled to the power amplifier power supply voltage through a corresponding one of the plurality of modulator output filters.

4. The envelope tracking system as described in claim 3, wherein, The effective number of the plurality of modulators is selected based on comparing the analog envelope signal with the plurality of signal thresholds.

5. The envelope tracking system as described in claim 1, wherein, The modulator is configured to receive the analog envelope signal via a mobile industry peripheral interface analog reference interface for envelope tracking.

6. The envelope tracking system as described in claim 1, wherein, The simulated envelope signal is a differential envelope signal.

7. The envelope tracking system as described in claim 6, wherein, The modulator includes: a differential envelope amplifier configured to amplify the differential envelope signal to generate a single-ended envelope signal; and a plurality of comparators, each of the comparators being configured to compare the single-ended envelope signal with a corresponding one of the plurality of signal thresholds.

8. The envelope tracking system as described in claim 1, wherein, Each of the plurality of signal thresholds is controllable.

9. The envelope tracking system as described in claim 1, wherein, The DC-DC converter is also configured to generate the DC voltage.

10. The envelope tracking system as claimed in claim 1, wherein, The DC path filter includes at least one series inductor and at least one parallel capacitor.

11. The envelope tracking system as claimed in claim 1, wherein, The modulator output filter includes at least one series inductor and at least one parallel capacitor.

12. The envelope tracking system of claim 11, wherein, The modulator output filter also includes a DC blocking capacitor connected in series between the modulator output voltage and the power amplifier power supply voltage.

13. An envelope tracker, comprising: The power amplifier power supply voltage terminal is configured to output the power amplifier power supply voltage for the power amplifier. A DC-DC converter configured to output multiple regulated voltages based on a regulated battery voltage; Modulator output filter; A DC path filter is coupled between the DC voltage from the DC-DC converter and the power amplifier supply voltage; as well as A modulator, including an output coupled to the power amplifier power supply voltage terminal via the modulator output filter, the modulator being configured to generate a modulator output voltage at the output based on the plurality of regulated voltages and an analog envelope signal, the modulator being configured to generate the modulator output voltage based on comparing the analog envelope signal with a plurality of signal thresholds, the DC path filter and the modulator output filter respectively filtering the DC voltage from the DC-DC converter and the modulator output voltage generated by the modulator, thereby generating the power amplifier power supply voltage for the power amplifier.

14. The envelope tracker of claim 13, further comprising: A plurality of modulators, including the modulators; and a plurality of modulator output filters, each of the plurality of modulators being coupled to the power amplifier power supply voltage terminal via a corresponding one of the plurality of modulator output filters.

15. The envelope tracker of claim 14, wherein, The effective number of the plurality of modulators is selected based on comparing the analog envelope signal with the plurality of signal thresholds.

16. The envelope tracker of claim 13, wherein, The analog envelope signal is a differential envelope signal, and the modulator includes: a differential envelope amplifier configured to amplify the differential envelope signal to generate a single-ended envelope signal; and a plurality of comparators, each of the comparators being configured to compare the single-ended envelope signal with a corresponding one of the plurality of signal thresholds.

17. A mobile device, comprising: A transceiver configured to generate radio frequency transmit 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; and A power management circuit includes an envelope tracker configured to generate a power amplifier supply voltage based on an analog 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 generate a modulator output voltage at its output based on the plurality of regulated voltages and the analog envelope signal; a modulator output filter coupled between the output of the modulator and the power amplifier supply voltage; and a DC path filter coupled between a DC voltage from the DC-DC converter and the power amplifier supply voltage. The modulator is configured to generate the modulator output voltage based on comparing the analog envelope signal with a plurality of signal thresholds. The DC path filter and the modulator output filter respectively filter the DC voltage from the DC-DC converter and the modulator output voltage generated by the modulator to generate the power amplifier supply voltage for the power amplifier.

18. The mobile device of claim 17, wherein, The envelope tracker further includes a plurality of modulators, the modulators comprising: a plurality of modulators including the modulators; and a plurality of modulator output filters including the modulator output filters, each of the plurality of modulators being coupled to the power amplifier power supply voltage via a corresponding one of the plurality of modulator output filters.

19. The mobile device of claim 18, wherein, The effective number of the plurality of modulators is selected based on comparing the analog envelope signal with the plurality of signal thresholds.

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