Doherty power amplifier having reduced size

Doherty power amplifier having reduced size. In some embodiments, a power amplification system can include a supply system configured to provide a high-voltage supply signal, and a Doherty power amplifier configured to receive the high-voltage supply signal and amplify a radio-frequency (RF) signal. The power amplification system can further include an output path configured to receive and route the amplified RF signal to a filter. The output path can be substantially free of an impedance transformation circuit.

BACKGROUND

Field

The present disclosure relates to power amplifiers for radio-frequency (RF) applications.

Description of the Related Art

In many radio-frequency (RF) applications, an RF signal to be transmitted is typically amplified by a power amplifier. Such a power amplifier can be implemented in a number of ways, including, for example, a Doherty power amplifier.

SUMMARY

According to some implementations, the present disclosure relates to a power amplification system that includes a supply system configured to provide a high-voltage (HV) supply signal, and a Doherty power amplifier (PA) configured to receive the HV supply signal and amplify a radio-frequency (RF) signal. The power amplification system further includes an output path configured to receive and route the amplified RF signal to a filter. The output path is substantially free of an impedance transformation circuit.

In some embodiments, the supply system can include a boost DC/DC converter configured to generate the HV supply signal based on a battery voltage Vbatt. The HV supply signal can be selected such that impedances of the Doherty PA and the filter match sufficiently to allow the output path to be substantially free of the impedance transformation circuit. The impedance of the Doherty PA can have a value of, for example, approximately 50 Ohms.

In some embodiments, the Doherty PA can includes a heterojunction bipolar transistor (HBT). The HBT can be a gallium arsenide (GaAs) device. The HV supply signal can be provided to a collector of the HBT as Vcc.

In some embodiments, the filter can be a transmit (Tx) filter configured to operate in a corresponding Tx frequency band. The Tx filter can be part of a duplexer configured to operate in the Tx frequency band and a corresponding receive (Rx) frequency band.

In some embodiments, the power amplification system can further include one or more additional Doherty PAs, with each configured to receive the HV supply signal and amplify an RF signal. The power amplification system can further include an output path configured to receive and route the amplified RF signal for each of the one or more additional Doherty PAs to a corresponding filter. The additional output path can be substantially free of an impedance transformation circuit.

In some embodiments, each filter can have associated with it a corresponding Doherty PA. The power amplification system can be substantially free of a band selection switch between the Doherty PAs and the filters. The power amplification system can have a lower loss than another power amplifier system having similar band handling capability but in which the PAs are operated in low voltage.

In some teachings, the present disclosure relates to a radio-frequency (RF) module that includes a packaging substrate configured to receive a plurality of components, and a power amplification system implemented on the packaging substrate. The power amplification system includes a supply system configured to provide a high-voltage (HV) supply signal, and a Doherty power amplifier (PA) configured to receive the HV supply signal and amplify an RF signal. The power amplification system further includes an output path configured to receive and route the amplified RF signal to a filter. The output path is substantially free of an impedance transformation circuit.

In some embodiments, the RF module can be a front-end module (FEM). In some embodiments, the power amplification system can be substantially free of a band selection switch between the Doherty PA and the filter. The power amplification system can have a lower loss than another power amplifier system having similar band handling capability but in which a Doherty PA is operated in low voltage. The RF module can have an area that is significantly less than another RF module having an amplification system with an impedance transformation circuit and a band selection switch.

In accordance with a number of implementations, the present disclosure relates to a wireless device having a transceiver configured to generate a radio-frequency (RF) signal, and a front-end module (FEM) in communication with the transceiver. The FEM includes a packaging substrate configured to receive a plurality of components, and a power amplification system implemented on the packaging substrate. The power amplification system includes a supply system configured to provide a high-voltage (HV) supply signal, and a Doherty power amplifier (PA) configured to receive the HV supply signal and amplify a radio-frequency (RF) signal. The power amplification system further includes an output path configured to receive and route the amplified RF signal to a filter. The output path is substantially free of an impedance transformation circuit. The wireless device further includes an antenna in communication with the FEM and configured to transmit the amplified RF signal.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

Referring toFIG. 1, one or more features of the present disclosure generally relate to a wireless system or architecture50having an amplification system52. In some embodiments, the amplification system52can be implemented as one or more devices, and such device(s) can be utilized in the wireless system/architecture50. In some embodiments, the wireless system/architecture50can be implemented in, for example, a portable wireless device. Examples of such a wireless device are described herein.

FIG. 2shows that the amplification system52ofFIG. 1typically includes a radio-frequency (RF) amplifier assembly54having one or more power amplifiers (PAs). In the example ofFIG. 2, three PAs60a-60care depicted as forming the RF amplifier assembly54. It will be understood that other numbers of PA(s) can also be implemented. It will also be understood that one or more features of the present disclosure can also be implemented in RF amplifier assemblies having other types of RF amplifiers.

In some embodiments, the RF amplifier assembly54can be implemented on one or more semiconductor die, and such die can be included in a packaged module such as a power amplifier module (PAM) or a front-end module (FEM). Such a packaged module is typically mounted on a circuit board associated with, for example, a portable wireless device.

The PAs (e.g.,60a-60c) in the amplification system52are typically biased by a bias system56. Further, supply voltages for the PAs are typically provided by a supply system58. In some embodiments, either or both of the bias system56and the supply system58can be included in the foregoing packaged module having the RF amplifier assembly54.

In some embodiments, the amplification system52can include a matching network62. Such a matching network can be configured to provide input matching and/or output matching functionalities for the RF amplifier assembly54.

For the purpose of description, it will be understood that each PA (60) ofFIG. 2can be implemented in a number of ways.FIGS. 3A-3Eshow non-limiting examples of how such a PA can be configured.FIG. 3Ashows an example PA having an amplifying transistor64, where an input RF signal (RF_in) is provided to a base of the transistor64, and an amplified RF signal (RF_out) is output through a collector of the transistor64.

FIG. 3Bshows an example PA having a plurality of amplifying transistors (e.g.,64a,64b) arranged in stages. An input RF signal (RF_in) is provided to a base of the first transistor64a, and an amplified RF signal from the first transistor64ais output through its collector. The amplified RF signal from the first transistor64ais provided to a base of the second transistor64b, and an amplified RF signal from the second transistor64bis output through its collector to thereby yield an output RF signal (RF_out) of the PA.

In some embodiments, the foregoing example PA configuration ofFIG. 3Bcan be depicted as two or more stages as shown inFIG. 3C. The first stage64acan be configured as, for example, a driver stage; and the second stage64bcan be configured as, for example, an output stage.

FIG. 3Dshows that in some embodiments, a PA can be configured as a Doherty PA. Such a Doherty PA can include amplifying transistors64a,64bconfigured to provide carrier amplification and peaking amplification of an input RF signal (RF_in) to yield an amplified output RF signal (RF_out). The input RF signal can be split into the carrier portion and the peaking portion by a splitter. The amplified carrier and peaking signals can be combined to yield the output RF signal by a combiner.

FIG. 3Eshows that in some embodiments, a PA can be implemented in a cascode configuration. An input RF signal (RF_in) can be provided to a base of the first amplifying transistor64aoperated as a common emitter device. The output of the first amplifying transistor64acan be provided through its collector and be provided to an emitter of the second amplifying transistor64boperated as a common base device. The output of the second amplifying transistor64bcan be provided through its collector so as to yield an amplified output RF signal (RF_out) of the PA.

In the various examples ofFIGS. 3A-3E, the amplifying transistors are described as bipolar junction transistors (BJTs) such as heterojunction bipolar transistors (HBTs). It will be understood that one or more features of the present disclosure can also be implemented in or with other types of transistors such as field-effect transistors (FETs).

FIG. 4shows that in some embodiments, the amplification system52ofFIG. 2can be implemented as a high-voltage (HV) power amplification system100. Such a system can include an HV power amplifier assembly54configured to include HV amplification operation of some or all of the PAs (e.g.,60a-60c). As described herein, such PAs can be biased by a bias system56. In some embodiments, the foregoing HV amplification operation can be facilitated by an HV supply system58. In some embodiments, an interface system72can be implemented to provide interface functionalities between the HV power amplifier assembly54and either or both of the bias system56and the HV supply system58.

Examples Related to HV Systems:

Many wireless devices such as cellular handsets are configured to support multiple frequency bands; and such devices typically require complex power amplification architectures. However, such complexity in power amplification architectures can result in degradation of transmit efficiency as the number of supported bands increases. Such a degradation in efficiency is typically largely due to increased loss incurred by combining of multiple frequency bands while maintaining competitive size and cost targets.

Some wireless systems can include power amplifiers (PAs) configured in a Doherty configuration. Such a configuration typically includes separate amplification paths for carrier and peaking portions of an RF signal. Such a signal is split into the two amplification path, and the separately amplified carrier and peaking portions are combined to generate an amplified output signal.

Described herein are examples of systems, circuits, devices and methods that can provide advantageous features for Doherty PAs. Such advantageous features can include, for example, significantly reduce loss while maintaining or improving competitive levels of size and/or cost.FIG. 5shows that in some embodiments, the HV power amplification system100ofFIG. 4can be configured as a Doherty power amplification system. In some embodiments, such a Doherty power amplification system can include high-voltage operation capability.

Doherty power amplification architectures can offer significant advantages for transmit efficiency with moderated peak-average waveforms. However, physical implementation of such architectures typically involves increased passive component content to provide functionalities such as phase shifting and impedance transformation networks at the amplifier output.

As described herein, a Doherty power amplification architecture can utilize a boost converter to increase the amplifier supply voltage to a level that allows amplifier operation at, for example, a 50 ohm impedance without impedance transformation networks. Such an architecture can allow, for example, significant simplification and integration of passive component content with a system bill of materials (BOM) comparable to a single ended amplification configuration.

In the example ofFIG. 5, an HV Doherty power amplification system100can include a power amplifier assembly104having one or more PAs configured to amplify one or more RF signals (RF_In). Such amplified RF signal(s) can be routed to a duplexer assembly108having one or more duplexers, through a match component106having one or more matching circuits.

The duplexer(s) can allow duplexing of transmit (Tx) and receive (Rx) operations. The Tx portion of such duplexing operations is depicted as one or more amplified RF signals (RF_Out) being output from the duplexer assembly108for transmission through an antenna (not shown). In the example ofFIG. 5, the Rx portion is not shown; however, received signals from an antenna can be received by the duplexer assembly108and output to, for example, low-noise amplifiers (LNAs).

In the example ofFIG. 5, an HV supply system102is shown to provide one or more HV supply signals to the power amplifier assembly104. More specific examples of how such HV signal(s) can be provided to corresponding PA(s) are described herein in greater detail.

In some embodiments, the HV Doherty power amplification system100ofFIG. 5can utilize high-voltage capability of some PAs such as, for example, gallium arsenide (GaAs) heterojunction bipolar transistor (HBT) PAs. It will be understood that one or more features of the present disclosure can also be implemented with other types of PAs. For example, amplification systems utilizing CMOS devices with LDMOS multiple cascode stages, silicon bipolar devices, and GaN/HEMT devices can also benefit from operation in high-voltage regions.

With such HV operation of PAs, one or more lossy components can be eliminated from an amplification system. For example, PA output matching network(s) can be eliminated. In another example, PA supply efficiency can be increased. In yet another example, some passive components can be removed. Examples related to the foregoing are described herein in greater detail.

One or more of the foregoing features associated with HV operation can result in one or more die being implemented in smaller dimensions, thereby allowing greater flexibility in power amplification system designs. For example, a power amplification system can be implemented with an increased number of relatively small PAs, to thereby allow elimination of lossy components such as band switches. Examples related to such elimination of band switches are described herein in greater detail.

For the purpose of description, it will be understood that high-voltage (HV) can include voltage values that are higher than a battery voltage utilized in portable wireless devices. For example, an HV can be greater than 3.7V or 4.2V. In some situations, an HV can include voltage values that are greater than a battery voltage and at which portable wireless devices can operate more efficiently. In some situations, an HV can include voltage values that are greater than a battery voltage and less than a breakdown voltage associated with a given type of PA. In the example context of GaAs HBT, such a breakdown voltage can be in a range of 15V to 25V. Accordingly, an HV for GaAs HBT PA can be in a range of, for example, 3.7V to 25V, 4.2V to 20V, 5V to 15V, 6V to 14V, 7V to 13V, or 8V to 12V.

FIGS. 6 and 7show a comparison between a traditional Doherty power amplification system110(FIG. 6) and a high-voltage (HV) Doherty power amplification system100(FIG. 7) to demonstrate how some lossy components can be substantially eliminated in the HV Doherty power amplification system100. For the purpose of comparison, it will be assumed that each power amplification system is configured to provide amplification for three frequency bands. However, it will be understood that more or less numbers of frequency bands can be utilized.

In the example ofFIG. 6, the traditional Doherty power amplification system110is shown to include a power amplifier assembly114having a broadband carrier amplification path130and a broadband peaking amplification path132capable of providing amplification for three frequency bands. In the example, each of the carrier and peaking amplification paths130,132is shown to include two stages (e.g., a driver stage (130aor132a) and an output stage (130bor132b)); however, it will be understood that there may be other number of stage(s).

The foregoing amplification paths130,132can receive an input RF signal through a common input node126, and such an RF signal can be routed through, for example, a DC-block capacitance128, and be split into the carrier amplification path130and the peaking amplification path132. In some embodiments, each of the amplification stages130a,130b,132a,132bcan include, for example, HBT or CMOS amplification transistors.

In the example ofFIG. 6, the collector of the output stage130bis shown to be provided with a supply voltage VCC from a battery voltage source (Vbatt) through a choke inductance124.

When the power amplifier assembly is operated in the foregoing manner, impedance transformation typically needs to occur to match the impedance of the PAs with impedance associated with a downstream component. In the example ofFIG. 6, a band switch138(depicted as being part of a band switch system118) that receives the output of the power amplifier assembly114is typically configured as a 50Ω load. Accordingly, an impedance transformation to yield such an impedance load of 50Ω needs to be implemented. In the example ofFIG. 6, such an impedance transformation is shown to be implemented by an output matching network (OMN)136which is depicted as being part of a load transform system116.

In the example ofFIG. 6, the band switch138is depicted as having a single input from the output of the power amplifier assembly114(through the OMN136), and three outputs corresponding to three example frequency bands. Three duplexers142a-142care shown to be provided for such three frequency bands.

Each of the three duplexers142a-142cis shown to include TX and RX filters (e.g., bandpass filters). The TX filter is shown to be coupled to the band switch138to receive the amplified and switch-routed RF signal for transmission. Such an RF signal is shown to be filtered and routed to an antenna port (ANT) (144a,144bor144c). The RX filter is shown to receive an RX signal from the antenna port (ANT) (144a,144bor144c). Such an RX signal is shown to be filtered and routed to an RX component (e.g., an LNA) for further processing.

It is typically desirable to provide impedance matching between a given duplexer and a component that is upstream (in the TX case) or downstream (in the RX case). In the example ofFIG. 6, the band switch138is such an upstream component for the TX filter of the duplexer. Accordingly, matching circuits140a-140c(depicted as being parts of a PI network120) are shown to be implemented between the respective outputs of the band switch138and the respective duplexers142a-142c. In some embodiments, each of such matching circuits140a-140ccan be implemented as, for example, a pi-matching circuit.

Table 1 lists example values of insertion loss and efficiency for the various components of the Doherty power amplification system110ofFIG. 6. It will be understood that the various values listed are approximate values.

TABLE 1ComponentInsertion lossEfficiencyPower Amp. Assy. (114)N/A60% to 65% (PAE)Load Transform (116)0.5 dB to 0.7 dB85% to 89%Band Switch (118)0.3 dB to 0.5 dB89% to 93%PI (120)0.3 dB93%Duplex (122)2.0 dB63%
From Table 1, one can see that the Doherty power amplification system110ofFIG. 6includes a significant number of loss contributors. Even if each component of the system110is assumed to operate at its upper limit of efficiency, the total efficiency of the ET power amplification system110is approximately 32% (0.65×0.89×0.93×0.93×0.63).

In the example ofFIG. 7, the HV Doherty power amplification system100is depicted as being configured to provide amplification for the same three frequency bands as in the Doherty power amplification system110ofFIG. 6. In a power amplifier assembly104, three separate amplification paths can be implemented, such that each amplification path provides amplification for its respective frequency band(s). For example, the first amplification path is shown to include a first Doherty PA (167aand168a) which receives an RF signal from an input node162athrough a DC-block capacitance164a. The amplified RF signal is shown to be routed to a downstream component through a capacitance170a. Similarly, the second amplification path is shown to include a second Doherty PA (167band168b) which receives an RF signal from an input node162bthrough a DC-block capacitance164b; and the amplified RF signal is shown to be routed to a downstream component through a capacitance170b. Similarly, the third amplification path is shown to include a third Doherty PA (167cand168c) which receives an RF signal from an input node162cthrough a DC-block capacitance164c; and the amplified RF signal is shown to be routed to a downstream component through a capacitance170c.

In some embodiments, the Doherty PAs in the example ofFIG. 7can include, for example, HBT PAs. It will be understood that one or more features of the present disclosure can also be implemented with other types of PAs. For example, PAs that can be operated to yield impedances that match or are close to downstream components (e.g., by HV operation and/or through other operating parameter(s)) can be utilized to yield one or more of the benefits as described herein.

In the example ofFIG. 7, each carrier PA (167a,167bor167c) can be provided with a supply voltage VCC from a boost DC/DC converter160through a choke inductance (166a,166bor166c). Similarly, each peaking PA (168a,168bor168c) can be provided with the supply voltage VCC from the boost DC/DC converter160through the choke inductance (166a,166bor166c). The boost DC/DC converter160is depicted as being part of an HV system102. The boost DC/DC converter160can be configured to supply such a range of VCC voltage values (e.g., about 1V to 10V), including HV ranges or values as described herein. The boost DC/DC converter160is shown to generate such a high VCC voltage based on a battery voltage Vbatt.

When the Doherty PAs of the power amplifier assembly104are operated in the foregoing manner with high VCC voltage (e.g., at about 10V), impedance Z of each PA can be relatively high (e.g., about 40Ω to 50Ω); and thus, impedance transformation is not necessary to match with impedance associated with a downstream component and/or an upstream component. Accordingly, elimination or simplification of two impedance transformation networks can be realized. It is further noted that the Doherty PAs of the power amplifier assembly104can support very simple integration of, for example, a quarter-wave combining network.

In the example ofFIG. 7, each of the duplexers174a-174c(depicted as being parts of a duplex assembly108) that receives the output of the corresponding Doherty PA is typically configured as a 50Ω load. Accordingly, and assuming that the impedance (Z) presented by the Doherty PA is about 50Ω, an impedance transformation (such as the load transform system116inFIG. 6) is not needed.

It is typically desirable to provide impedance matching between a given duplexer and a component that is upstream (in the TX case) or downstream (in the RX case). In the example ofFIG. 7, the Doherty PA is such an upstream component for the TX filter of the duplexer (174a,174bor174c). Accordingly, matching circuits172a-172c(depicted as being parts of a PI network106) can be implemented between the respective outputs of the Doherty PAs and the respective duplexers174a-174c. In some embodiments, each of such matching circuits172a-172ccan be implemented as, for example, a pi-matching circuit.

In the example ofFIG. 7, the HV operation of the Doherty PAs can result in each of the Doherty PAs presenting an impedance Z that is similar to the impedance of the corresponding duplexer. Since impedance transformation is not needed in such a configuration, there is no need for an impedance transformer (116inFIG. 6).

It is also noted that operation of the Doherty PAs at the higher impedance can result in much lower current levels within the PAs. Such lower current levels can allow the Doherty PAs to be implemented in significantly reduced die size(s).

In some embodiments, either or both of the foregoing features (elimination of impedance transformer and reduced PA die size) can provide additional flexibility in power amplification architecture design. For example, space and/or cost savings provided by the foregoing can allow implementation of a relatively small Doherty PA for each frequency band, thereby removing the need for a band switch system (e.g.,118inFIG. 6). Accordingly, size, cost and/or complexity associated with the HV Doherty power amplification system100ofFIG. 7can be maintained or reduced when compared to the Doherty power amplification system110ofFIG. 6, while significantly reducing the overall loss of the power amplification system100.

Table 2 lists example values of insertion loss and efficiency for the various components of the HV Doherty power amplification system100ofFIG. 7. It will be understood that the various values listed are approximate values.

From Table 2, one can see that the HV Doherty power amplification system100ofFIG. 7includes a number of loss contributors. However, when compared to the Doherty power amplification system110ofFIG. 6and Table 1, two significant loss contributors (Load Transform (116) and Band Switch (118)) are absent in the HV Doherty power amplification system100ofFIG. 7. Elimination of such loss contributors is shown to remove about 1 dB in the transmit path in the example ofFIG. 7and Table 2.

Also referring to Table 2, if each component of the system100is assumed to operate at its upper limit of efficiency (as in the example of Table 1), the total efficiency of the HV Doherty power amplification system100is approximately 44% (0.93×0.80×0.93×0.63). Even if each component is assumed to operate at its lower limit of efficiency, the total efficiency of the HV Doherty power amplification system100is approximately 41% (0.93×0.75×0.93×0.63). One can see that in either case, the total efficiency of the HV Doherty power amplification system100ofFIG. 7is significantly higher than the total efficiency (approximately 32%) of the Doherty power amplification system110ofFIG. 6.

Referring toFIGS. 6 and 7, a number of features can be noted. It is noted that use of the DC/DC boost converter (160inFIG. 7) can allow elimination of one or more other power converters that may be utilized in a PA system. When operated to yield an HV supply voltage (e.g., 10 VDC), 1 Watt (10V)2/(2×50Ω)) of RF power can be produced with no harmonic terminations. It is further noted that a PA driven as a 50Ω load (e.g.,FIG. 7) results in a significantly lower loss per Ohm than a PA driven as a 3Ω load (e.g.,FIG. 6).

FIG. 8shows an HV Doherty power amplification system100that can be a more specific example of the HV Doherty power amplification system100ofFIG. 7. In the example ofFIG. 8, a power amplifier assembly can include a carrier PA167and a peaking PA168. Each of the carrier and peaking PAs is depicted as having a cascode configuration.

In the example ofFIG. 8, the carrier PA167can be operated with, for example, a Class AB bias; and the peaking PA168can be operated with, for example, a Class C bias. More particularly, the RF transistor of the carrier PA167is shown to be biased in a Class AB configuration; and the RF transistor of the peaking PA168is shown to be biased in a Class C configuration. The cascode transistor of each of the carrier and peaking PAs167,168is shown to be biased by its respective cascode bias circuit.

In the example ofFIG. 8, an RF signal can be received at a common input port162(RFin), and such a signal can be split into the carrier amplification path and the peaking amplification path by an input splitter202. The carrier portion is shown to be provided to the carrier PA167, and the peaking portion is shown to be provided to the peaking PA168through an input inverter204.

In the example ofFIG. 8, a supply voltage Vcc from a supply node212is shown to be provided to the collector of each cascode transistor of the carrier and peaking PAs167,168. More particularly, the collector of the cascode transistor of the carrier PA167is shown to be provided with Vcc through inductances indicated as Choke and Linv. The collector of the cascode transistor of the peaking PA168is shown to be provided with Vcc through Linv.

The collector of the cascode transistor of the carrier PA167is shown to be coupled to the emitter of the RF transistor of the carrier PA167through a corresponding capacitance Cinv. Similarly, the collector of the cascode transistor of the peaking PA168is shown to be coupled to the emitter of the RF transistor of the peaking PA168through a corresponding capacitance Cinv.

In the example ofFIG. 8, an assembly of the capacitances Cinv and the inductance Linv can form an output J-inverter210having an impedance of, for example, approximately 100Ω. The amplified outputs of the carrier and peaking PAs167,168can be combined by the output J-inverter210, and the combined output can be provided to an output node214through a capacitance170.

As shown inFIG. 8, the high impedance operation of the Doherty PAs can significantly simplify the Doherty amplification architecture, including the simplification of the combining network (e.g., the output J-inverter210). In some embodiments, the carrier and peaking PAs167,168can be implemented on a die. In some embodiments, the input splitter202and the input J-inverter204can also be implemented on the same die. In some embodiments, the inverter capacitances (Cinv) of the output J-inverter210can also be implemented on the same die. Accordingly, and assuming that the inverter inductance Linv is implemented as an external passive device, only one such additional passive device is needed when compared to a single-ended power amplification design.

FIG. 9shows an HV Doherty amplification system that can be a more specific example of the HV Doherty amplification system ofFIG. 8. InFIG. 9, reference numerals202,204,207,208and210generally correspond to the same reference numerals ofFIG. 8. In the example ofFIG. 9, it will be understood that various values of circuit elements such as resistances, capacitances and inductances can be selected to achieve desired functionalities for one or more frequencies.

FIGS. 10-12show examples of performance characteristics of the HV Doherty amplification system ofFIG. 9. More particularly,FIG. 10shows plots of AMAM vs output power, PAE vs output power, ratio of peak power and carrier power vs input power, and collector current vs output power, as Class C bias point is swept.

FIG. 11shows gain, output power, emitter follower bias, and collector current characteristics for Class AB and Class C bias configurations.

FIG. 12shows AMAM, PAE, and AMPM characteristics for the HV Doherty amplification system, as well as for a single ended amplification system.

FIG. 13shows examples of battery level efficiency as a function of average output power for a Buck ET amplification system (A), a boost average power tracking (APT) amplification system (B), a Buck APT amplification system (C), and a boost Doherty amplification system (D) having one or more features as described herein. At an example output power of about 26 dBm, one can see that the boost Doherty amplification system (D) has an efficiency level that is about 15% greater than both of the Buck ET (A) and boost APT (B) systems, and about 25% greater than the Buck APT system (C).

FIG. 14shows that in some embodiments, some or all of an HV Doherty power amplification system having one or more features as described herein can be implemented in a module. Such a module can be, for example, a front-end module (FEM). In the example ofFIG. 14, a module300can include a packaging substrate302, and a number of components can be mounted on such a packaging substrate. For example, a front-end-power management integrated circuit (FE-PMIC) component102, a power amplifier assembly104, a match component106, and a duplexer assembly108can be mounted and/or implemented on and/or within the packaging substrate302. Other components such as a number of SMT devices304and an antenna switch module (ASM)306can also be mounted on the packaging substrate302. Although all of the various components are depicted as being laid out on the packaging substrate302, it will be understood that some component(s) can be implemented over other component(s).

In some implementations, a device and/or a circuit having one or more features described herein can be included in an RF device such as a wireless device. Such a device and/or a circuit can be implemented directly in the wireless device, in a modular form as described herein, or in some combination thereof. In some embodiments, such a wireless device can include, for example, a cellular phone, a smart-phone, a hand-held wireless device with or without phone functionality, a wireless tablet, etc.

FIG. 15depicts an example wireless device400having one or more advantageous features described herein. In the context of a module having one or more features as described herein, such a module can be generally depicted by a dashed box300, and can be implemented as, for example, a front-end module (FEM).

Referring toFIG. 15, power amplifiers (PAs)420can receive their respective RF signals from a transceiver410that can be configured and operated in known manners to generate RF signals to be amplified and transmitted, and to process received signals. The transceiver410is shown to interact with a baseband sub-system408that is configured to provide conversion between data and/or voice signals suitable for a user and RF signals suitable for the transceiver410. The transceiver410can also be in communication with a power management component406that is configured to manage power for the operation of the wireless device400. Such power management can also control operations of the baseband sub-system408and the module300.

The baseband sub-system408is shown to be connected to a user interface402to facilitate various input and output of voice and/or data provided to and received from the user. The baseband sub-system408can also be connected to a memory404that is configured to store data and/or instructions to facilitate the operation of the wireless device, and/or to provide storage of information for the user.

In the example wireless device400, outputs of the PAs420are shown to be matched (via respective match circuits422) and routed to their respective duplexers420. In some embodiments, the match circuit422can be the example matching circuits172a-172cdescribed herein in reference toFIG. 7. As also described herein in reference toFIG. 7, the outputs of the PAs420can be routed to their respective duplexers424without impedance transformation (e.g., with load transformation116inFIG. 6) when the PAs420are operated with HV supply. Such amplified and filtered signals can be routed to an antenna416through an antenna switch414for transmission. In some embodiments, the duplexers420can allow transmit and receive operations to be performed simultaneously using a common antenna (e.g.,416). InFIG. 15, received signals are shown to be routed to “Rx” paths (not shown) that can include, for example, a low-noise amplifier (LNA).

A number of other wireless device configurations can utilize one or more features described herein. For example, a wireless device does not need to be a multi-band device. In another example, a wireless device can include additional antennas such as diversity antenna, and additional connectivity features such as Wi-Fi, Bluetooth, and GPS.

As described herein, one or more features of the present disclosure can provide a number of advantages when implemented in systems such as those involving the wireless device ofFIG. 15. For example, significant current drain reduction can be achieved through an elimination or reduction of output loss. In another example, lower bill of materials count can be realized for the power amplification system and/or the wireless device. In yet another example, independent optimization or desired configuration of each supported frequency band can be achieved due to, for example, separate PAs for their respective frequency bands. In yet another example, optimization or desired configuration of maximum or increased output power can be achieved through, for example, a boost supply voltage system. In yet another example, a number of different battery technologies can be utilized, since maximum or increased power is not necessarily limited by battery voltage.

One or more features of the present disclosure can be implemented with various cellular frequency bands as described herein. Examples of such bands are listed in Table 3. It will be understood that at least some of the bands can be divided into sub-bands. It will also be understood that one or more features of the present disclosure can be implemented with frequency ranges that do not have designations such as the examples of Table 3.