Portable device, power amplification system, and method of power amplification

Abstract

To provide a power amplifier including a supply capacitor switching.SOLUTION: A power amplifier system 110 includes a power amplifier 102 that amplifies a radio frequency (RF) signal, a power management circuit 101 that controls the voltage level of supply voltage VCC of the power amplifier 102, a supply capacitor 103 including a first end connected to the supply voltage VCC, and a bulk n-type field effect transistor (NFET) switch. A power management circuit 101 can operate in a multi-supply control mode (for example, average power trace mode and envelope trace mode). Additionally, a bulk NFET switch is controlled based on the supply control mode of the power management circuit 101. The bulk NFET switch includes a ground NFET connected in series with a second end of the supply capacitor 103 and ground voltage, and a discharge NFET connected between the second end of the supply capacitor and the supply voltage VCC.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] FIELD OF THE INVENTION 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 radio frequency (RF) communication systems, power amplifiers are used to amplify RF signals for transmission via antennas. Managing the power of RF signal transmissions can be important to extend battery life and / or provide adequate transmit power levels.

[0003] Examples of RF communication systems having one or more power amplifiers include, but are not limited to, mobile phones, tablets, base stations, network access points, laptops, and wearable electronic devices. The power amplifier amplifies an RF signal, which may have a frequency in the range of about 30 kHz to 300 GHz, such as in the range of about 410 MHz to about 7.125 GHz for fifth-generation (5G) communications using Frequency Range 1 (FR1) or in the range of about 24.25 GHz to 52.6 GHz for 5G communications using Frequency Range 2 (FR2). Summary of the Invention

[0004] In certain embodiments, the present disclosure relates to a portable device including a power amplifier configured to amplify radio frequency signals, a power management circuit configured to control a voltage level of a supply voltage of the power amplifier, the power management circuit operable in a selected supply control mode selected from a plurality of supply control modes, and a front-end system including a supply capacitor having a first end connected to the supply voltage, an n-type field effect transistor ground switch connected between a second end of the supply capacitor and ground, and an n-type field effect transistor discharge switch connected between the second end of the supply capacitor and the supply voltage, the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch being controlled based on the selected supply control mode.

[0005] In some embodiments, the plurality of supply control modes includes an average power tracking mode and an envelope tracking mode. According to certain embodiments, the n-type field effect transistor ground switch is configured to be on in the average power tracking mode and off in the envelope tracking mode, and the n-type field effect transistor discharge switch is configured to be off in the average power tracking mode and on in the envelope tracking mode.

[0006] In various embodiments, the n-type field effect transistor discharge switch includes two or more n-type field effect transistors in series. According to some embodiments, the front-end system further includes a voltage divider configured to bias the two or more n-type field effect transistors. According to certain embodiments, the voltage divider includes a first terminal connected to the supply voltage and a second terminal connected to a ground voltage through a mode transistor. According to some embodiments, the plurality of supply control modes includes an average power tracking mode and an envelope tracking mode, and the mode transistor is configured to be on in the envelope tracking mode and off in the average power tracking mode.

[0007] In some embodiments, the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch are implemented in a semiconductor die fabricated using a bulk silicon process.

[0008] In certain embodiments, the present disclosure relates to a package module. The package module includes a package substrate and a first die mounted to the package substrate, the first die including a power amplifier configured to amplify radio frequency signals and receive power from a supply voltage controlled by a power management circuit. The package module further includes a supply capacitor mounted to the package substrate and having a first end connected to the supply voltage, and a second die mounted to the package substrate, the second die being fabricated using a bulk silicon process. The second die includes an n-type field effect transistor ground switch connected between the second end of the supply capacitor and ground, and an n-type field effect transistor discharge switch connected between the second end of the supply capacitor and the supply voltage.

[0009] In various embodiments, the power management circuitry is operable in a select supply control mode indicating one of an average power tracking mode or an envelope tracking mode, and the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch are controlled based on the select supply control mode. According to some embodiments, the n-type field effect transistor ground switch is configured to be on in the average power tracking mode and off in the envelope tracking mode, and the n-type field effect transistor discharge switch is configured to be off in the average power tracking mode and on in the envelope tracking mode.

[0010] In some embodiments, the n-type field effect transistor discharge switch includes two or more n-type field effect transistors in series. According to certain embodiments, the second die further includes a voltage divider configured to bias the two or more n-type field effect transistors. According to some embodiments, the voltage divider includes a first terminal connected to a supply voltage and a second terminal connected to a ground voltage through a mode transistor.

[0011] In various embodiments, the package module further includes a supply pin configured to receive a supply voltage, and the power management circuitry is external to the package module.

[0012] In certain embodiments, the present disclosure relates to a power amplifier system including: a power amplifier configured to amplify a radio frequency signal; a power management circuit configured to control a voltage level of a supply voltage of the power amplifier, the power management circuit operable in a selected supply control mode selected from a plurality of supply control modes; a supply capacitor having a first end connected to the supply voltage; an n-type field effect transistor ground switch connected between a second end of the supply capacitor and a ground voltage; and an n-type field effect transistor discharge switch connected between the second end of the supply capacitor and the supply voltage, wherein the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch are controlled based on the selected supply control mode.

[0013] In various embodiments, the plurality of supply control modes includes an average power tracking mode and an envelope tracking mode. According to certain embodiments, the n-type field effect transistor ground switch is configured to be on in the average power tracking mode and off in the envelope tracking mode, and the n-type field effect transistor discharge switch is configured to be off in the average power tracking mode and on in the envelope tracking mode.

[0014] In some embodiments, the n-type field effect transistor discharge switch includes two or more n-type field effect transistors in series. According to certain embodiments, the power amplifier system further includes a voltage divider configured to bias the two or more n-type field effect transistors. According to various embodiments, the voltage divider includes a first terminal connected to the supply voltage and a second terminal connected to a ground voltage through a mode transistor. According to some embodiments, the plurality of supply control modes includes an average power tracking mode and an envelope tracking mode, and the mode transistor is configured to be on in the envelope tracking mode and off in the average power tracking mode.

[0015] In various embodiments, the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch are implemented in a semiconductor die fabricated using a bulk silicon process.

[0016] In certain embodiments, the present disclosure relates to a method of power amplification, the method including amplifying a radio frequency signal using a power amplifier and controlling a voltage level of a supply voltage of the power amplifier using a power management circuit, the supply voltage being coupled to a first end of a supply capacitor. The method further includes operating the power management circuit in a selected supply control mode selected from a plurality of supply control modes and controlling an n-type field effect transistor ground switch based on the selected supply control mode, the n-type field effect transistor ground switch being connected between a second end of the supply capacitor and ground. The method further includes controlling an n-type field effect transistor discharge switch based on the selected supply control mode, the n-type field effect transistor ground switch being connected between the second end of the supply capacitor and the supply voltage.

[0017] In various embodiments, the plurality of supply control modes includes an average power tracking mode and an envelope tracking mode. According to some embodiments, the method further includes turning on an n-type field effect transistor ground switch in the average power tracking mode and turning off the n-type field effect transistor ground switch in the envelope tracking mode. According to some embodiments, the method further includes turning off an n-type field effect transistor discharge switch in the average power tracking mode and turning on the n-type field effect transistor discharge switch in the envelope tracking mode. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram of an example of a communication network. [Figure 2A] FIG. 1 is a schematic diagram of an example of a communication link using carrier aggregation. [Figure 2B] 2B illustrates various examples of uplink carrier aggregation for the communication link of FIG. 2A. [Figure 2C] 2B illustrates various examples of downlink carrier aggregation for the communication link of FIG. 2A. [Figure 3A] 1 is a graph illustrating a first example of power amplifier supply voltage versus time. [Figure 3B] 10 is a graph illustrating a second example of power amplifier supply voltage versus time. [Figure 3C] 10 is a graph illustrating a third example of power amplifier supply voltage versus time. [Figure 4] FIG. 1 is a schematic diagram of a power amplifier system according to an embodiment. [Figure 5] FIG. 10 is a schematic diagram of a power amplifier system according to another embodiment. [Figure 6A] FIG. 10 is a schematic diagram of a power amplifier system according to another embodiment. [Figure 6B] 6B is a graph of an example of supply mode switching waveforms for the power amplifier system of FIG. 6A. [Figure 7A] FIG. 2 is a schematic diagram of a package module according to an embodiment. [Figure 7B] FIG. 7B is a schematic cross-sectional view of the package module taken along line 7B-7B in FIG. 7A. [Figure 8] FIG. 1 is a schematic diagram of a mobile device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in numerous different forms, as defined and covered, for example, by the claims. Reference is made herein to the drawings in which like reference numbers indicate identical or functionally similar elements. It is understood that the elements depicted in the drawings are not necessarily drawn to scale. It is further understood that certain embodiments may include more elements than shown in the drawings and / or a subset of the elements depicted in the drawings. Furthermore, some embodiments may include any suitable combination of features from two or more drawings.

[0020] 1 is a schematic diagram of an example of a communications network 10. The communications network 10 includes a macrocell base station 1, a small cell base station 3, and various examples of user equipment (UE), including a first mobile device 2a, a wirelessly connected car 2b, a laptop 2c, a stationary wireless device 2d, a wirelessly connected train 2e, a second mobile device 2f, and a third mobile device 2g.

[0021] Although particular examples of base stations and user equipment are shown in FIG. 1, a communications network may include many different types and / or numbers of base stations and user equipment.

[0022] For example, in the illustrated example, communication network 10 includes a macrocell base station 1 and a small cell base station 3. Small cell base station 3 may operate at relatively lower power, shorter distances, and / or fewer concurrent users than macrocell base station 1. Small cell base station 3 may also be referred to as a femtocell, picocell, or microcell. Although communication network 10 is shown as including two base stations, communication network 10 may be implemented to include more or fewer base stations and / or other types of base stations.

[0023] Although various examples of user equipment are shown, the teachings herein are applicable to a wide variety of user equipment, including, but not limited to, mobile phones, tablets, laptops, Internet of Things (IoT) devices, wearable electronics, customer premises equipment (CPE), wirelessly connected vehicles, wireless relays, and / or a wide variety of other communication devices. Furthermore, user equipment includes not only currently available communication devices that operate in cellular networks, but also subsequently developed communication devices that can readily implement the inventive systems, processes, methods, and devices described and claimed herein.

[0024] 1 supports communications using various cellular technologies, including, for example, 4G LTE and 5G NR. In certain implementations, the communications network 10 is further adapted to provide a wireless local area network (WLAN), such as WiFi. Although various examples of communications technologies have been provided, the communications network 10 may be adapted to support a wide variety of communications technologies.

[0025] Various communication links of communication network 10 are depicted in FIG. 1. The communication links may be duplexed in a variety of ways, including, for example, using frequency division duplexing (FDD) and / or time division duplexing (TDD). FDD is a type of radio frequency communication that uses different frequencies for transmitting and receiving signals. FDD can offer several advantages, such as high data rates and low latency. In contrast, TDD is a type of radio frequency communication that uses approximately the same frequency for transmitting and receiving signals, with transmit and receive communications alternating in time. TDD can offer several advantages, such as efficient use of spectrum and variable allocation of throughput between transmit and receive directions.

[0026] In certain implementations, user equipment may communicate with base stations using one or more of 4G LTE, 5G NR, and WiFi technologies. In certain implementations, enhanced license-assisted access (eLAA) is used to aggregate one or more licensed frequency carriers (e.g., licensed 4G LTE and / or 5G NR frequencies) with one or more unlicensed carriers (e.g., unlicensed WiFi frequencies).

[0027] 1, the communication links include not only communication links between UEs and base stations, but also UE-to-UE communication and base station-to-base station communication. For example, communication network 10 may be implemented to support self-fronthaul and / or self-backhaul (e.g., between mobile device 2g and mobile device 2f).

[0028] The communication link can operate over a wide variety of frequencies. In certain implementations, communication is supported using 5G NR technology over one or more frequency bands below 6 gigahertz (GHz) and / or over one or more frequency bands above 6 GHz. For example, the communication link can provide Frequency Range 1 (FR1), Frequency Range 2 (FR2), or a combination thereof. In one embodiment, one or more of the mobile devices support the HPUE power class specification.

[0029] In certain implementations, base stations and / or user equipment communicate using beamforming. For example, beamforming can be used to converge signal strength to overcome path losses, such as high losses associated with communication over high signal frequencies. In certain embodiments, one or more user equipment, such as mobile phones, communicate using beamforming in the millimeter wave frequency band ranging from 30 GHz to 300 GHz and / or in the upper centimeter wave frequencies ranging from 6 GHz to 30 GHz, particularly 24 GHz to 30 GHz.

[0030] Different users of communication network 10 may share available network resources, such as the available frequency spectrum, in a wide variety of ways.

[0031] In one example, frequency division multiple access (FDMA) is used to divide a frequency band into multiple frequency carriers, with one or more carriers allocated to a particular user. Examples of FDMA include, but are not limited to, single-carrier FDMA (SC-FDMA) and orthogonal FDMA (OFDMA). OFDMA is a multi-carrier technique that divides the available bandwidth into multiple mutually orthogonal narrowband subcarriers that can be allocated separately to different users.

[0032] Other examples of shared access include, but are not limited to, time division multiple access (TDMA), in which users are assigned specific time slots to use the frequency resources, code division multiple access (CDMA), in which frequency resources are shared among different users by assigning each user a unique code, spatial division multiple access (SDMA), in which beamforming is used to provide shared access through spatial division, and non-orthogonal multiple access (NOMA), in which power domains are used for multiple access purposes. For example, NOMA may be used to serve multiple users with the same frequency, time, and / or code but at different power levels.

[0033] Enhanced Mobile Broadband (eMBB) refers to technology that increases the system capacity of LTE networks. For example, eMBB may refer to communication with a peak data rate of at least 10 Gbps and a minimum of 100 Mbps for each user. Ultra-reliable low-latency communication (uRLLC) refers to technology for very low-latency communication, e.g., less than 2 milliseconds. uRLLC can be used for mission-critical communications, such as for autonomous driving and / or remote surgery applications. Massive Machine-Type Communication (mMTC) refers to low-cost, low-data-rate communications associated with wireless connections to everyday objects, e.g., communications associated with Internet of Things (IoT) applications.

[0034] The communications network 10 of FIG. 1 may be used to support a wide variety of advanced communications features, including, but not limited to, eMBB, uRLLC, and / or mMTC.

[0035] 2A is a schematic diagram of an example communication link using carrier aggregation, which can be used to increase the bandwidth of a communication link by supporting communication across multiple frequency carriers, thereby increasing user data rates, and improving network capacity by utilizing fragmented spectrum allocations.

[0036] In the illustrated example, a communication link is provided between a base station 21 and a mobile device 22. As shown in Figure 2A, the communication link includes a downlink channel (DL) used for RF communication from the base station 21 to the mobile device 22 and an uplink channel (UL) used for RF communication from the mobile device 22 to the base station 21.

[0037] Although FIG. 2A illustrates carrier aggregation in the context of FDD communications, carrier aggregation can also be used for TDD communications.

[0038] In certain implementations, the communication link may provide asymmetric data rates for the downlink and uplink channels. For example, the communication link may support a relatively high downlink data rate to enable high-speed streaming of multimedia content to a mobile device, while providing a relatively low data rate for uploading data from the mobile device to the cloud.

[0039] In the illustrated example, the base station 21 and the mobile device 22 communicate via carrier aggregation, which can be used to selectively increase the bandwidth of the communication link. Carrier aggregation includes contiguous aggregation, where contiguous carriers are aggregated within the same operating frequency band. Carrier aggregation may also be non-contiguous, and may include frequency-separated carriers within a common band or within different bands.

[0040] In the example shown in FIG. 2A, the uplink channel is divided into three aggregated component carriers f UL1 , f UL2 and f UL3 Additionally, the downlink channel includes five aggregated component carriers f DL1 , f DL2 , f DL3 , f DL4 and f DL5 Although an example component carrier aggregation is shown, more or fewer carriers may be aggregated for the uplink and / or downlink. Furthermore, the number of aggregated carriers may be varied over time to achieve desired uplink and downlink data rates.

[0041] For example, the number of carriers aggregated for uplink and / or downlink communications for a particular mobile device may change over time, e.g., as the device moves through the communications network and / or as network usage conditions change over time.

[0042] Figure 2B shows various examples of uplink carrier aggregation for the communication link of Figure 2A, including a first carrier aggregation scenario 31, a second carrier aggregation scenario 32, and a third carrier aggregation scenario 33, which schematically depict three types of carrier aggregation.

[0043] Carrier aggregation scenarios 31 to 33 are based on the first component carrier f UL1 , second component carrier f UL2 , and the third component carrier f UL32B illustrates different spectrum allocations for the uplink and downlink. Although FIG. 2B is shown in the context of aggregating three component carriers, carrier aggregation can also be used to aggregate more or fewer carriers. Furthermore, although shown in the context of the uplink, the aggregation scenario is also applicable to the downlink.

[0044] The first carrier aggregation scenario 31 illustrates intra-band contiguous carrier aggregation, in which component carriers that are adjacent in frequency and within a common frequency band are aggregated. For example, the first carrier aggregation scenario 31 illustrates intra-band contiguous carrier aggregation, in which component carriers f UL1 , f UL2 and f UL3 Draw the aggregation of.

[0045] Continuing with reference to FIG. 2B, a second carrier aggregation scenario 32 illustrates intra-band non-contiguous carrier aggregation in which two or more component carriers at non-adjacent frequencies but within a common frequency band are aggregated. For example, the second carrier aggregation scenario 32 illustrates an ... UL1 , f UL2 and f UL3 Draw the aggregation of.

[0046] The third carrier aggregation scenario 33 illustrates intra-band discontinuous carrier aggregation in which component carriers at non-adjacent frequencies and in multiple frequency bands are aggregated. For example, the third carrier aggregation scenario 33 illustrates intra-band discontinuous carrier aggregation in which component carriers f UL1 and f UL2 and component carrier f of the second frequency band BAND2 UL3 It depicts the convergence of

[0047] 2C illustrates various examples of downlink carrier aggregation for the communication link of FIG. 2A. These examples are for the first component carrier fDL1 , second component carrier f DL2 , third component carrier f DL3 , 4th component carrier f DL4 and 5th component carrier f DL5 2B depicts various carrier aggregation scenarios 34-38 for different spectrum allocations. Although FIG. 2B is shown in the context of aggregating five component carriers, carrier aggregation can also be used to aggregate more or fewer carriers. Furthermore, although shown in the context of the downlink, the aggregation scenarios are also applicable to the uplink.

[0048] A first carrier aggregation scenario 34 illustrates the aggregation of component carriers that are contiguous and located within the same frequency band. Additionally, a second carrier aggregation scenario 35 and a third carrier aggregation scenario 36 illustrate two examples of aggregations that are discontinuous but located within the same frequency band. Furthermore, a fourth carrier aggregation scenario 37 and a fifth carrier aggregation scenario 38 illustrate two examples of aggregations in which component carriers that are non-adjacent frequencies and located within multiple frequency bands are aggregated. As the number of component carriers to be aggregated increases, the complexity of the possible carrier aggregation scenarios also increases.

[0049] 2A-2C, individual component carriers used in carrier aggregation may have different frequencies, including, for example, frequency carriers in the same band or in multiple bands. Additionally, carrier aggregation is applicable to implementations where individual component carriers have approximately the same bandwidth, as well as implementations where individual component carriers have different bandwidths.

[0050] A given communication network allocates a primary component carrier (PCC) or anchor carrier for the uplink and a PCC for the downlink to a particular user device. Additionally, if a mobile device communicates using a single frequency carrier for the uplink or downlink, the user device communicates using the PCC. To improve bandwidth for uplink communications, an uplink PCC can be aggregated with one or more uplink secondary component carriers (SCCs). Additionally, to improve bandwidth for downlink communications, a downlink PCC can be aggregated with one or more downlink SCCs.

[0051] In certain implementations, a communication network provides a network cell for each component carrier. Additionally, the primary cell operates using a PCC, while the secondary cell operates using an SCC. The primary and secondary cells may have different coverage areas due to differences in carrier frequencies and / or network environments.

[0052] Licensed Assisted Access (LAA) refers to downlink carrier aggregation in which licensed frequency carriers associated with a mobile operator i are aggregated with frequency carriers in an unlicensed spectrum, such as WiFi. LAA uses a downlink PCC in the licensed spectrum to carry control and signaling information associated with the communication link, while unlicensed spectrum is aggregated for wider downlink bandwidth, when available. LAA may operate by dynamically adjusting secondary carriers to avoid and / or coexist with WiFi users. Enhanced Licensed Assisted Access (eLAA) refers to an evolution of LAA that aggregates licensed and unlicensed spectrum for both the downlink and uplink.

[0053] Power amplifier with supply capacitor switching

[0054] In mobile applications such as cellular communication systems, extending battery life is important, and one operation that consumes a significant amount of battery charge is power amplification, or the amplification of RF signals for wireless transmission.

[0055] To increase efficiency and thereby extend battery life, a portable device may include a power management circuit that controls the voltage level of a power amplifier's supply voltage. For example, the power management circuit may use various power management techniques to vary the voltage level of the power amplifier's supply voltage over time to improve the power added efficiency (PAE) of the power amplifier, thereby reducing power dissipation and extending battery life.

[0056] One technique for power management of power amplifiers is average power tracking (APT), in which a DC / DC converter or other suitable voltage regulator is used to generate a supply voltage for a power amplifier based on the average output power of the power amplifier. For example, with APT, the supply voltage may be set to a particular voltage level over a certain time interval (e.g., a fixed voltage level over a transmission frame) based on the average output power over that time interval.

[0057] Another technique for improving the efficiency of a power amplifier is envelope tracking (ET). In this case, the supply voltage of the power amplifier is controlled in relation to the envelope of the RF signal. That is, if the voltage level of the envelope of the RF signal increases, the voltage level of the supply voltage of the power amplifier can be increased. Similarly, if the voltage level of the envelope of the RF signal decreases, the voltage level of the supply voltage of the power amplifier decreases, reducing power consumption.

[0058] The power amplifier system may be multi-mode and may be specified to operate in a linear mode (APT mode) with a static DC power supply or in a quasi-compressed mode (ET mode) with a dynamically varying power supply.

[0059] 4G / 5G waveforms contain amplitude modulation (AM) characteristics that result in rapidly changing current characteristics in the power amplifier. Furthermore, it is preferable to have a large value of capacitance in the supply network during APT operation because the finite impedance of the power amplifier supply network can cause degradation in power amplifier linearity. Conversely, during ET operation, the power amplifier supply is specified to support high frequency modulation and therefore cannot tolerate a large amount of capacitance in the power amplifier supply network.

[0060] For example, a mobile device may include a shared power management circuit that can be configured in APT mode or ET mode depending on signal power levels and operating characteristics, e.g., whether 3G, 4G, and / or 5G waveforms are used. In APT mode, it is desirable for the power management circuit to drive large capacitances (e.g., in the 1 uF range), while in ET mode (particularly for 5G applications), it is desirable for the load capacitance to be limited to a few hundred pF for a wide envelope tracking bandwidth. For 5G applications in APT mode, it is desirable for the power amplifier to operate with a large source capacitance in the range of a few nanofarads (nF) to meet adjacent channel power ratio (ACPR) and / or adjacent channel leakage power ratio (ACLR) specifications.

[0061] A power amplifier with supply capacitor switching is provided herein. In certain embodiments, the power amplifier system includes a power amplifier for amplifying an RF signal, a power management circuit for controlling a voltage level of a supply voltage of the power amplifier, a supply capacitor having a first end connected to the supply voltage, and a bulk n-type field effect transistor (NFET) switch. The power management circuit is operable in multiple supply control modes, including, for example, an APT mode and an ET mode. Additionally, the bulk NFET switch is controlled based on the supply control mode of the power management circuit. The bulk NFET switch includes a ground NFET in series with a second end of the supply capacitor and a ground voltage, and a discharge NFET connected between the second end of the supply capacitor and the supply voltage.

[0062] Therefore, the power amplifier can be designed to support multiple supply control modes, such as APT and ET modes, and operate between them with optimal or near-optimal performance. Furthermore, the supply capacitors can be switched using a low-cost, low-complexity switch solution that utilizes only NFET devices in bulk silicon technology.

[0063] In contrast, approaches using bulk silicon p-type field-effect transistors (PFETs) can provide isolation (e.g., using a triple-well CMOS process) to avoid voltage swings below ground and / or forward bias of substrate parasitic capacitance, but they suffer significant difficulties in supporting low-voltage DC supply conditions and / or the additional well capacitance of large PFETs significantly limits the minimum capacitance state during ET mode. In another example, an NFET switch can be connected between the supply capacitor and ground, and a charge pump can be used to bias the gate of the NFET switch above the supply voltage. However, this approach requires an additional pin interface to supply the charge pump circuit and increases the risk of clock spurious signals (clock spurs) corrupting the power amplifier transmit spectrum. In yet another example, SOI technology can be used to avoid body effects, but this SOI technology adds significant cost due to complex semiconductor processes.

[0064] 3A is a first example graph 47 of power amplifier supply voltage versus time. Graph 47 plots the voltage of the RF signal 41, the RF signal envelope 42, and the power amplifier supply voltage 43 over time. Graph 47 corresponds to an example waveform for an implementation in which the power amplifier supply voltage 43 is substantially fixed.

[0065] It may be important that the power amplifier supply voltage 43 of the power amplifier have a greater voltage than the RF signal 41. For example, powering the power amplifier using a power amplifier supply voltage with a smaller amplitude than the RF signal may clip the RF signal, resulting in signal distortion and / or other problems. That is, it may be important that the power amplifier supply voltage 43 be greater than the voltage of the envelope 42. However, it is desirable to reduce the voltage difference between the power amplifier supply voltage 43 and the envelope 42 of the RF signal 41, because the area between the power amplifier supply voltage 43 and the envelope 42 may represent energy loss. This energy loss may reduce battery life and increase heat generated in the wireless device.

[0066] 3B is a second example graph 48 of power amplifier supply voltage versus time. Graph 48 plots the voltage of the RF signal 41, the RF signal envelope 42, and the power amplifier supply voltage 44 over time. Graph 48 corresponds to an example waveform for an implementation in which power amplifier supply voltage 44 is generated by envelope tracking.

[0067] Envelope tracking is a technique that can be used to increase the power-added efficiency (PAE) of a power amplifier system by effectively controlling the voltage level of the power amplifier supply voltage in relation to the envelope of the RF signal that the power amplifier amplifies. That is, if the envelope of the RF signal increases, the voltage supplied to the power amplifier may also increase. Similarly, if the envelope of the RF signal decreases, the voltage supplied to the power amplifier will also decrease, resulting in lower power consumption.

[0068] In contrast to power amplifier supply voltage 43 of Figure 3A, power amplifier supply voltage 44 of Figure 3B varies relative to envelope 42 of RF signal 41. Because the area between power amplifier supply voltage 44 and envelope 42 in Figure 3B is smaller than the area between power amplifier supply voltage 43 and envelope 42 in Figure 3A, graph 48 of Figure 3B can be associated with a more energy efficient power amplifier system.

[0069] 3C is a third example graph 49 of power amplifier supply voltage versus time. Graph 49 plots the voltage of the RF signal 41, the RF signal envelope 42, and the power amplifier supply voltage 45 over time. Graph 49 corresponds to an example waveform for an implementation in which power amplifier supply voltage 45 is generated by average power tracking (APT).

[0070] APT is a technique for improving the efficiency of a power amplifier. In this case, the voltage level of the power amplifier supply voltage is controlled based on the average output power of the power amplifier. When operating using APT, the voltage level of the power amplifier supply voltage is substantially fixed for a particular time slot or time interval, but is adjusted for subsequent time slots based on the average output power (e.g., transmit power control level). APT can achieve gain more efficiently than a fixed power amplifier supply voltage, but the gain is less efficient than envelope tracking. However, envelope tracking may require more complexity, cost, and / or overhead than APT.

[0071] 4 is a schematic diagram of one embodiment of a power amplifier system 70. The exemplary power amplifier system 70 includes a switch 51, an antenna 52, a directional coupler 54, a power management circuit 60, a bias control circuit 61, a power amplifier 62, a transceiver 63, and a baseband processor 64.

[0072] 4 illustrates one embodiment of a power amplifier system, the teachings herein are applicable to power amplifier systems implemented in a wide variety of ways. For example, a power amplifier system may include more or fewer components, different component arrangements, and / or components implemented in different ways.

[0073] In the illustrated embodiment, transceiver 63 includes power amplifier control circuitry 66, I / Q modulator 67, mixer 68, and analog-to-digital converter (ADC) 69. Although not shown in FIG. 4 for clarity, transceiver 63 may also process signals received from one or more antennas (e.g., antenna 52 and / or other antennas) via one or more receive paths. Additionally, transceiver 63 may be implemented in other manners, including, but not limited to, using different implementations of transmit paths, observation paths, and / or power amplifier control circuitry.

[0074] The baseband processor 64 may be used to generate in-phase (I) and quadrature (Q) signals that may be used to represent a sine wave or sinusoidal signal of a desired amplitude, frequency, and phase. For example, the I signal may be used to represent the in-phase component of a sine wave, and the Q signal may be used to represent the quadrature component of the sine wave, thereby providing an equivalent representation of the sine wave. In certain implementations, the I and Q signals are provided to the I / Q modulator 67 in digital form. The baseband processor 64 may be any suitable processor configured to process baseband signals. For example, the baseband processor 64 may include a digital signal processor, a microprocessor, a programmable core, or any combination thereof. Furthermore, in some implementations, more than one baseband processor 64 may be included in the power amplifier system 70.

[0075] The I / Q modulator 67 is configured to receive the I and Q signals from the baseband processor 64 and process the I and Q signals to generate an RF signal. For example, the I / Q modulator 67 may include a number of digital-to-analog converters (DACs) that convert the I and Q signals to analog form, a mixer that upconverts the I and Q signals to RF, and a signal combiner that combines the upconverted I and Q signals into an RF signal suitable for amplification by the power amplifier 62. In certain implementations, the I / Q modulator 67 may include one or more filters configured to filter frequency components of the signal being processed.

[0076] Power amplifier 62 may receive an RF signal from I / Q modulator 67 and, when enabled, provide the amplified RF signal to antenna 52 via switch 51. A directional coupler 54 may be placed between the output of power amplifier 62 and the input of switch 51. This allows for measurement of the output power of power amplifier 62 without including the insertion loss of switch 51. However, other power measurement configurations are possible.

[0077] Switch 51, in this embodiment, includes an antenna switch and / or a band switch. Switch 51 may further include one or more supply control switches (each connected to a corresponding supply capacitor) implemented in accordance with the teachings herein. Such supply control switches may be used for any or all of the stages of power amplifier 62.

[0078] In the illustrated configuration, the detected output signal from the directional coupler 54 is provided to a mixer 68, which multiplies the detected output signal by a reference signal at a controlled frequency. The mixer 68 operates to generate a downshifted signal by downshifting a frequency component of the detected output signal. The downshifted signal may be provided to an ADC 69, which can convert the downshifted signal to a digital format suitable for processing by the baseband processor 64. By including a feedback path between the output of the power amplifier 62 and the baseband processor 64, the baseband processor 64 can be configured to dynamically adjust the I and Q signals to optimize operation of the power amplifier system 70. For example, configuring the power amplifier system 70 in this manner can assist in controlling the PAE and / or linearity of the power amplifier 62.

[0079] In the illustrated embodiment, power management circuit 60 receives a power control signal from transceiver 63 to control the supply voltage of power amplifier 62. In certain implementations, transceiver 63 is electrically connected to power management circuit 60 via a serial interface, and power management circuit 60 receives the power control signal via the serial interface.

[0080] As shown in FIG. 4, power management circuit 60 generates a first supply voltage V for powering the input stage of power amplifier 62. CC1 and a second supply voltage V for powering the output stage of the power amplifier 62. CC2 The power management circuit 60 generates a first supply voltage V CC1 and / or a second supply voltage V CC2 Although one embodiment with two controllable supply voltages is shown, the power management circuitry can control the voltage levels of more or fewer supply voltages. In certain implementations, the power amplifier operates with one or more controllable supply voltages and one or more substantially fixed supply voltages.

[0081] In the illustrated embodiment, the power control signal instructs the power management circuit 60 to operate in a particular supply control mode, such as APT mode or ET mode, i.e., the power amplifier control circuit 66 of the transceiver 63 controls the selected supply control mode in this embodiment.

[0082] 4, the bias control circuit 61 receives one bias control signal from the transceiver 63 and generates multiple bias control signals for the power amplifier 62. Additionally, the bias control circuit 61 generates multiple bias control signals based on the one bias control signal.

[0083] The bias control signal indicates a supply control mode in which the power management circuit 60 operates, and the bias control circuit 61 generates multiple bias control signals based on the indicated supply control mode. In certain implementations, the transceiver 63 is electrically connected to the bias control circuit 61 via a serial interface, and the bias control circuit 61 receives a control word via the serial interface indicating a selected supply control mode.

[0084] 5 is a schematic diagram of another embodiment of a power amplifier system 110. The power amplifier system 110 includes a power management circuit 101, a power amplifier 102, a supply capacitor 103, and a switch die 104.

[0085] As shown in FIG. 5, the power amplifier 102 receives an RF input signal RF IN The power amplifier 102 receives an RF input signal RF IN is amplified to produce the RF output signal RF OUT Although depicted as including a single stage that generates a power amplifier supply voltage V, power amplifier 102 may include additional stages. Power amplifier 102 receives a power amplifier supply voltage V from a power management circuit 101, also referred to herein as a power management integrated circuit (PMIC). CC In certain implementations, the power amplifier 102 receives the power amplifier supply voltage V through a choke inductor. CC A power amplifier supply voltage V is supplied to the power amplifier through a bipolar transistor or choke inductor having a collector that receives CC The amplifier includes a field effect transistor (FET) having a drain receiving the

[0086] The power management circuit 101 controls the power amplifier supply voltage V CC The power management circuit 101 is a multi-mode power management circuit capable of operating in two or more modes, which may include an APT mode and an ET mode.

[0087] 5, switch die 104 includes supply capacitor switch 105, which may be implemented according to any of the embodiments herein. In certain embodiments, switch die 104 may include one or more other components to enhance integration.

[0088] The supply capacitor switch 105 is controlled (eg, open or closed) based on the mode of the power management circuit 101 as indicated by the mode signal MODE.

[0089] As shown in FIG. 5, the supply capacitor 103 is connected to the power amplifier supply voltage V CC and a second terminal (also referred to herein as a second terminal) connected to the supply capacitor switch 105.

[0090] Supply capacitor 103 can be selectively included to regulate the power amplifier supply voltage V by controlling the state of supply capacitor switch 105. CC can be filtered / stabilized.

[0091] 6A is a schematic diagram of another embodiment of a power amplifier system 210. The power amplifier system 210 is connected to a power amplifier supply voltage V CC a power management integrated circuit (PMIC) (not shown in FIG. 6A) that generates a power amplifier supply voltage V CC 6A), a bulk silicon switch die 201, a first supply capacitor C1, and a second supply capacitor C2. In this example, the bulk silicon switch die 201 is a flip-chip die, and bump inductances L1, L2, and L3 (corresponding to the inductances of the bump pads of the die) are shown for given pads of the die 201.

[0092] In the illustrated embodiment, bulk silicon switch die 201 includes pins or pads 202a, 202b, 202c, and 202d, a first NFET M1, a second NFET M2A / M2B, a third NFET M3, gate resistors RG1 and RG2, voltage divider resistors R1 and R2, a gate capacitor CG, and electrostatic discharge (ESD) protection circuitry including forward diode D1 and reverse diodes D2A, D2B, ... D2M, D2N.

[0093] Pin 202b is connected (through bump inductance L2) to the supply voltage V CC and a first end of supply capacitor C1, while pin 202a is connected (through bump inductance L1) to the second end of supply capacitor C1. Additionally, pin 202c is connected (through bump inductance L3) to ground, and pin 202d receives an APT enable signal APT_EN.

[0094] In the illustrated embodiment, NFET M1 is switched to the ground side of capacitor C1, which greatly simplifies the design because the APD enable signal APT_EN can directly control the gate of the NFET switch, without the need for complex circuitry such as a charge pump to bias the gate of the switch FET.

[0095] Care must be taken during ET operation, as capacitor C1 can become fully charged and low voltage values ​​on the supply will force the drain of the NFET ground switch (M1) below chip ground voltage, forward biasing the substrate parasitic capacitance.

[0096] In the illustrated embodiment, a discharge NFET (implemented in this example using the series combination of M2A and M2B) is active during ET mode, shorting out capacitor C1, causing it to discharge to a single diode voltage. As a result, very little charge remains on capacitor C1, and the supply V CC The low voltage transition of does not cause forward biasing of the substrate parasitic capacitance. The discharge NFET is also called a discharge switch.

[0097] In an effort to increase the robustness of the discharge switch, the device is segmented, and in this embodiment, configured in a stacked configuration M2A / M2B. Similarly, the gate bias is biased using resistor dividers R1 and R2. As a result, all drain-gate, source-gate, and drain-source voltages are divided, effectively doubling the voltage handling capacity of the discharge switch compared to a single-transistor configuration. However, the discharge switch may be implemented using more or fewer transistors.

[0098] An additional diode structure in parallel with the discharge switch provides an ESD protection path for this relatively small NFET structure. Because NFET M1 is large, it provides self-protection in this example via a natural snapback breakdown mechanism.

[0099] The use of a discharge switch offers the advantage of utilizing low-cost process technology through the use of an NFET-only switching architecture. Furthermore, the relatively small FET size and the absence of a bias well structure result in low off-state capacitance.

[0100] FIG. 6B is a graph of an example of supply mode switching waveforms for the power amplifier system of FIG. 6A.

[0101] APT enable signal APT_EN and supply voltage V CC An example waveform of the supply voltage V CC operates with various 1 μs and 3 μs transitions as shown.

[0102] Figure 7A is a schematic diagram of one embodiment of a package module 300. Figure 7B is a schematic cross-sectional view of the package module 300 taken along line 7B-7B in Figure 7A.

[0103] Package module 300 includes a power amplifier die 301, a switch die 302, surface mount components 303, wire bonds 308, a package substrate 320, and an encapsulation structure 340. Package substrate 320 includes pads 306 formed from conductors disposed therein. Additionally, dies 301 and 302 include pads 304, and wire bonds 308 are used to connect pads 304 of dies 301 and 302 to pads 306 of package substrate 320.

[0104] The power amplifier die 301 and the switch die 302 are implemented in accordance with one or more features of the present disclosure. In certain implementations, the switch die 302 includes a supply capacitor switch in series with a supply capacitor formed, at least in part, using a surface-mount capacitor attached to the package substrate. To enhance integration, the switch die 302 may include an antenna switch (e.g., a transmit / receive (T / R) switch) and / or a band switch. The switch die 302 may include a pin for receiving a control signal indicating a supply control mode of a power management circuit (which may be included on or external to the package module 300).

[0105] In a given implementation, the dies 301, 302 may be fabricated using different processing technologies. In one example, the power amplifier die 301 is fabricated using a heterojunction bipolar transistor (HBT) process, and the switch die 302 is fabricated using a bulk silicon process.

[0106] Packaging substrate 320 may be configured to receive multiple components, such as dies 301, 302 and surface mount components 303, which may include surface mount capacitors and / or inductors.

[0107] As shown in FIG. 7B , the package module 300 includes a plurality of contact pads 332. The plurality of contact pads 332 are positioned on the side of the package module 300 opposite the side used to attach the dies 301 and 302. Configuring the package module 300 in this manner can assist in connecting the package module 300 to a circuit board, such as a phone board for a wireless device. Example contact pads 332 can be configured to provide RF signals, bias signals, power (low voltage) and / or power (high voltage) to the dies 301 and 302 and / or surface-mounted components 303. As shown in FIG. 7B , electrical connection between the contact pads 332 and the die 301 can be facilitated by connections 333 through the package substrate 320. The connections 333 can represent electrical paths formed through the package substrate 320, such as connections associated with vias and conductors in a multi-layer stack package substrate.

[0108] In some embodiments, package module 300 may also include one or more package structures, for example, to provide protection and / or facilitate handling of package module 300. Such package structures may include an overmold or encapsulation structure 340 formed over package substrate 320 and the components and die disposed thereon.

[0109] It will be understood that although package module 300 is depicted in the context of wire bond based electrical connections, one or more features of the present disclosure may be implemented in other package configurations, such as, for example, a flip chip configuration.

[0110] 8 is a schematic diagram of one embodiment of a mobile device 800. 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.

[0111] Although the portable device 800 illustrates one example of an RF system that may incorporate one or more features of the present disclosure, the teachings herein are applicable to electronic systems implemented in a wide variety of ways.

[0112] The mobile device 800 can be used to communicate using a wide variety of communication technologies, including, but not limited to, 2G, 3G, 4G (LTE, LTE Advanced, and LTE Advanced Pro), 5G, WLAN (e.g., Wi-Fi), WPAN (e.g., Bluetooth® and ZigBee®), WPAN (e.g., WiMax), and / or GPS technologies.

[0113] The transceiver 802 generates RF signals for transmission and processes incoming RF signals received from the antenna 804. It will be appreciated that various functions associated with transmitting and receiving RF signals may be accomplished by one or more components collectively represented in Figure 8 as transceiver 802. In one example, separate components (e.g., separate circuits or dies) may be provided to handle certain types of RF signals.

[0114] 8, the transceiver 802 is connected to the front-end system 803 and to the power management circuit 805 using a serial interface 809. All or some of the RF components shown may be controlled by the serial interface 809 to configure the mobile device 800 during initialization and / or full operation. In other embodiments, the baseband processor 801 may additionally or alternatively be connected to the serial interface 809 and operate to configure one or more RF components, such as components of the front-end system 803 and / or the power management system 805.

[0115] The front-end system 803 assists in conditioning signals transmitted to and / or received from the antenna 804. In the illustrated embodiment, the front-end system 803 includes one or more supply capacitor switches 810, one or more power amplifiers (PAs) 811, one or more low noise amplifiers (LNAs) 812, one or more filters 813, one or more switches 814, and one or more duplexers 815. However, other implementations are possible.

[0116] For example, the front-end system 803 may provide a number of functions, including, but not limited to, amplifying transmit signals, amplifying receive signals, filtering signals, switching between different bands, switching between different power modes, switching between transmit and receive modes, duplexing signals, multiplexing signals (e.g., diplexing or triplexing), or any combination thereof.

[0117] In certain implementations, the mobile device 800 supports carrier aggregation, providing flexibility for increasing peak data rates. Carrier aggregation can be used for both frequency division duplexing (FDD) and time division duplexing (TDD), and may be used to aggregate multiple carriers or channels. Carrier aggregation includes contiguous aggregation, in which contiguous carriers are aggregated within the same operating frequency band. Carrier aggregation may also be non-contiguous, including frequency-separated carriers within a common band or different bands.

[0118] The multiple antennas 804 may include antennas used for a variety of different types of communication. For example, the antennas 804 may include antennas for transmitting and / or receiving signals associated with a variety of different frequencies and communication standards.

[0119] In certain implementations, the antennas 804 support MIMO and / or switched diversity communications. For example, MIMO communications use multiple antennas to communicate multiple data streams over a single radio frequency channel. MIMO communications benefit from high signal-to-noise ratios, improved coding, and / or reduced signal interference due to spatial multiplexing in the wireless environment. Switched diversity refers to communications in which a particular antenna is selected to operate at a particular time. For example, a switch can be used to select a particular antenna from a group of antennas based on various factors, such as an observed bit error rate and / or signal strength indicator.

[0120] The mobile device 800 may operate with beamforming in certain implementations. 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 may be controlled to provide beamforming and directionality for transmitting and / or receiving signals using the antenna 804. For example, in the context of signal transmission, the phase of transmit signals provided to the antenna 804 may be controlled such that signals radiating from the antenna 804 combine using constructive and destructive interference to generate an aggregate transmit signal exhibiting beam-like qualities with strong signal strength propagating in a given direction. In the context of signal reception, the phase may be controlled such that more signal energy is received when the signal arrives at the antenna 804 from a particular direction. In certain implementations, the antenna 804 may include one or more arrays of antenna elements to enhance beamforming.

[0121] The baseband system 801 is coupled to a user interface 807 that facilitates the processing of various user inputs and outputs (I / O), such as voice and data. The baseband system 801 provides a digital representation of a transmit signal to the transceiver 802, which processes it to generate an RF signal for transmission. The baseband system 801 also processes a digital representation of a receive signal that is provided by the transceiver 802. As shown in FIG. 8, the baseband system 801 is coupled to a memory 806 to facilitate operation of the mobile device 800.

[0122] The memory 806 may be used for a wide variety of purposes, such as storing data and / or instructions to facilitate operation of the mobile device 800 and / or to provide storage of user information.

[0123] The power management system 805 provides a number of power management functions for the portable device 800. In certain implementations, the power management system 805 includes a power amplifier (PA) supply control circuit that controls the supply voltages of the plurality of power amplifiers 811. For example, the power management system 805 may be configured to vary the supply voltage provided to one or more of the plurality of power amplifiers 811 to improve efficiency, such as power added efficiency (PAE).

[0124] The power management system 805 can operate in a selectable supply control mode, such as an APT mode or an ET mode. In the illustrated embodiment, the selected supply control mode of the power management system 805 is controlled by the transceiver 802. In certain implementations, the transceiver 802 controls the selected supply control mode using a serial interface 809. One or more supply control switches 810 are opened or closed based on the selected supply control mode.

[0125] 8, power management system 805 receives a battery voltage from battery 808. Battery 808 may be any suitable battery, including, for example, a lithium-ion battery, for use in portable device 800. Although power management system 805 is shown separate from front-end system 803, in certain implementations, all or a portion of power management system 805 (e.g., PA supply control circuitry) may be integrated into front-end system 803.

[0126] application

[0127] Although some of the above-described embodiments have been given as examples relating to wireless or mobile devices, the principles and advantages of these embodiments can be used for any other system or device requiring a power amplifier system.

[0128] Such power amplifier systems can be implemented in a variety of electronic devices. Examples of electronic devices may include, but are not limited to, consumer electronic products, components of consumer electronic products, electronic test equipment, etc. Examples of electronic devices also include, but are not limited to, memory chips, memory modules, circuitry for optical or other communications networks, and disk driver circuits. Examples of consumer electronic products include, but are not limited to, mobile phones, telephones, televisions, computer monitors, computers, handheld computers, personal digital assistants (PDAs), microwave ovens, refrigerators, automobiles, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, MP3 players, radios, camcorders, cameras, digital cameras, portable memory chips, washing machines, dryers, washer / dryers, copiers, facsimile machines, scanners, multifunction peripheral devices, watches, clocks, etc. Additionally, electronic devices may include unfinished products.

[0129] Conclusion

[0130] Unless the context clearly requires otherwise, throughout the specification and claims, terms like "comprises," "comprises," and the like should be interpreted in an inclusive sense, i.e., "including, but not limited to," as opposed to an exclusive or exhaustive sense. The term "coupled," as generally used herein, refers to two or more elements being connected either directly or via one or more intermediate elements. Similarly, the term "connected," as generally used herein, also refers to two or more elements being connected either directly or via one or more intermediate elements. Additionally, when used in this application, the terms "herein," "above," "below," and words of similar import shall refer to this application as a whole, and not to any particular portions of this application. Where the context permits, terms in the above Detailed Description using singular or plural numbers may also include the plural or singular number, respectively. The terms "or" and "or" referring to a list of two or more items cover all of the following interpretations of that term: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0131] Furthermore, unless specifically stated or understood otherwise within the context of use, conditional language used herein, such as "can," "could," "may," "might," "for example," and "such as," among others, generally intends that certain embodiments include certain features, elements, and / or conditions, while other embodiments do not. That is, such conditional language generally is not intended to imply that features, elements, and / or conditions are present in any manner required in one or more embodiments, or that one or more embodiments necessarily include logic that determines, with or without authorial input or prompting, whether or not those features, elements, and / or conditions are included or should be performed in any particular embodiment.

[0132] The above description of embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above. While 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 are possible within the scope of the invention. For example, while processes or blocks are presented in a given order, alternative embodiments may perform routines or use systems having blocks with steps in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and / or modified. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks may be shown to be performed in serial, these processes or blocks may instead be performed in parallel or may be performed at different times.

[0133] The teachings of the invention provided herein may be applied to other systems, not necessarily those described above. Elements and acts of the various embodiments described above may be combined to provide further embodiments.

[0134] While certain embodiments of the present invention have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms, and various omissions, substitutions, and modifications of the forms of the methods and systems described herein may be made without departing from the spirit of the present disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as fall within the scope and spirit of the present disclosure.

Claims

1. 1. A mobile device, comprising: a power amplifier configured to amplify a radio frequency signal; a power management circuit configured to control a voltage level of a supply voltage of the power amplifier; Front-end systems and Including, the power management circuitry is operable in a selected supply control mode selected from a plurality of supply control modes including an average power tracking mode and an envelope tracking mode; The front-end system includes: a supply capacitor having a first end connected to the supply voltage; an n-type field effect transistor ground switch connected between the second end of the supply capacitor and a ground voltage; an n-type field effect transistor discharge switch connected between the second end of the supply capacitor and the supply voltage; Including, the n-type field effect transistor discharge switch includes two or more n-type field effect transistors connected in series; the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch are controlled based on the selective supply control mode; the front-end system further includes a voltage divider configured to bias the two or more n-type field effect transistors; the n-type field effect transistor ground switch is configured to be turned on to connect the second end of the supply capacitor to the ground voltage in the average power tracking mode and turned off to disconnect the second end of the supply capacitor from the ground voltage in the envelope tracking mode.

2. A portable device as claimed in claim 1, wherein the n-type field effect transistor discharge switch is configured to be off in the average power tracking mode and on in the envelope tracking mode.

3. 2. The portable device of claim 1, wherein the voltage divider includes a first terminal connected to the supply voltage and a second terminal connected to the ground voltage through a mode transistor.

4. A portable device as claimed in claim 3, wherein the mode transistor is configured to be on in the envelope tracking mode and off in the average power tracking mode.

5. 10. The portable device of claim 1, wherein the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch are implemented on a semiconductor die fabricated using a bulk silicon process.

6. 1. A power amplifier system comprising: a power amplifier configured to amplify a radio frequency signal; a power management circuit configured to control a voltage level of a supply voltage of the power amplifier; a supply capacitor having a first end connected to the supply voltage; an n-type field effect transistor ground switch connected between the second end of the supply capacitor and a ground voltage; an n-type field effect transistor discharge switch connected between the second end of the supply capacitor and the supply voltage; Voltage divider and Including, the n-type field effect transistor discharge switch includes two or more n-type field effect transistors connected in series; the power management circuitry is operable in a selected supply control mode selected from a plurality of supply control modes including an average power tracking mode and an envelope tracking mode; the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch are controlled based on the selective supply control mode; the voltage divider is configured to bias the two or more n-type field effect transistors; the n-type field effect transistor ground switch is configured to be turned on to connect the second end of the supply capacitor to the ground voltage in the average power tracking mode and turned off to disconnect the second end of the supply capacitor from the ground voltage in the envelope tracking mode.

7. A power amplifier system as claimed in claim 6, wherein the n-type field effect transistor discharge switch is configured to be off in the average power tracking mode and on in the envelope tracking mode.

8. 7. The power amplifier system of claim 6, wherein the voltage divider includes a first terminal connected to the supply voltage and a second terminal connected through a mode transistor to the ground voltage.

9. The power amplifier system of claim 8, wherein the mode transistor is configured to be on in the envelope tracking mode and off in the average power tracking mode.

10. 7. The power amplifier system of claim 6, wherein the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch are implemented on a semiconductor die fabricated using a bulk silicon process.

11. 1. A method of power amplification, comprising: amplifying the radio frequency signal using a power amplifier; controlling a voltage level of a supply voltage of the power amplifier using a power management circuit, the supply voltage being coupled to a first end of a supply capacitor; operating the power management circuitry in a selected supply control mode selected from a plurality of supply control modes including an average power tracking mode and an envelope tracking mode; Controlling an n-type field effect transistor ground switch based on the selected supply control mode, wherein the n-type field effect transistor ground switch is connected between the second end of the supply capacitor and a ground voltage; controlling an n-type field effect transistor discharge switch based on the selected supply control mode, the n-type field effect transistor discharge switch including two or more n-type field effect transistors connected in series, and the n-type field effect transistor ground switch connected between the second end of the supply capacitor and the supply voltage; biasing the two or more n-type field effect transistors using a voltage divider; turning on the n-type field effect transistor ground switch to connect the second end of the supply capacitor to the ground voltage in the average power tracking mode and turning off the n-type field effect transistor ground switch to disconnect the second end of the supply capacitor from the ground voltage in the envelope tracking mode; A method comprising:

12. turning on the n-type field effect transistor discharge switch in the average power tracking mode; turning off the n-type field effect transistor discharge switch in the envelope tracking mode; 12. The method of claim 11, further comprising:

13. 12. The method of claim 11, wherein the voltage divider includes a first terminal connected to the supply voltage and a second terminal connected through a mode transistor to the ground voltage.

14. The method of claim 13, further comprising turning on the mode transistor in the envelope tracking mode and turning off the mode transistor in the average power tracking mode.

15. 12. The method of claim 11, wherein the n-type field effect transistor ground switch and the n-type field effect transistor discharge switch are implemented on a semiconductor die fabricated using a bulk silicon process.

16. The mobile device of claim 1 , further comprising an antenna configured to transmit the amplified radio frequency signal provided by the power amplifier.

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