HK1240414A1 - Doherty power amplifier with tunable input network - Google Patents

Description

Doherty power amplifier with tunable input network

Cross reference to related applications

This application claims priority to U.S. provisional application No.62/068,629 entitled "program INPUT with amplitude AND PHASE CONTROL FOR linear BROAD-BAND double power patent" filed on 25/10/2014, the disclosure of which is hereby expressly incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates generally to Radio Frequency (RF) Power Amplifiers (PAs).

Background

Multi-mode/multi-band (MMMB) Power Amplifier Modules (PAMs) may face competition from Envelope Tracking (ET) PAM in, for example, the 4G LTE market. To be successful in such a market, it is desirable for MMMB PAM to provide significant performance improvements over existing MMMB PAM and also to be able to compete with ET-based PAM (based on cost, performance and size).

In the 4G LTE standard, new modulation protocols such as OFDMA (orthogonal frequency division multiple access) and SC-FDMA (single carrier FDMA) can be used to support high data rates in scalable channel bandwidths of, for example, 5MHz-20MHz and even 40 MHz. High data rate transmission using many independently modulated subcarriers over a variable channel bandwidth in a 4G LTE communication protocol typically comes at the expense of a high peak-to-average power ratio (PAPR) for the transmitter. From a power amplifier perspective, high PAPR modulation schemes typically translate into low average efficiency since power amplifiers typically need to operate in deep back-off (deep-back-off) mode most of the time, away from their peak efficiency point, to prevent clipping of the transmitted signal. Therefore, for the 4G standard, a new configuration of power amplifier that can operate with high linearity and high PAE even under significant back-off conditions is desired.

For efficiency improvement under backoff, doherty PAM is able to meet high efficiency with high linearity under backoff, with greatly reduced system complexity and reduced calibration and Digital Predistortion (DPD) specifications compared to envelope tracking PAM. However, some doherty power amplifier configurations are bandwidth limited due to the narrow-band nature of existing doherty power combiners. Further, due to dynamically changing load lines, some doherty PAMs may have large AM-AM (amplitude modulation to amplitude modulation) and AM-PM (amplitude modulation to phase modulation) distortions at back-off, which may affect the FOM (quality factor) available at the rated power level of the 4G LTE communication standard. For wideband doherty PAM it may be desirable to be able to control such distortion under back-off conditions, especially when the wideband doherty PAM is implemented over a wide band.

Disclosure of Invention

According to certain embodiments, the present disclosure relates to an input network for a doherty power amplifier. The input network includes a splitter circuit configured to receive a Radio Frequency (RF) signal and to split the RF signal into a first portion along a first path to a carrier amplifier of the doherty power amplifier and a second portion along a second path to a peak amplifier of the doherty power amplifier. The input network also includes a tunable input circuit implemented along either or both of the first path and the second path. The tunable input circuit is configured to provide control of amplitude and phase of either or both of the first and second portions.

In some embodiments, the tunable input circuit may include an RC circuit. In some embodiments, the RC circuit may include a first capacitor along the first path, a first resistor in a bypass configuration between the first capacitor and the carrier amplifier, a second resistor along the second path, and a second capacitor in a bypass configuration between the second resistor and the peaking amplifier. In some embodiments, the first capacitor, the first resistor, the second capacitor, and the second resistor may each be tunable. In some embodiments, the first and second capacitors may each comprise a switchable capacitor bank, and the first and second resistors may each comprise a switchable resistor bank.

In some embodiments, the tunable input circuit may include an RLC circuit. In some embodiments, the RLC circuit may include a capacitor along the first path, a first resistor along the first path, an inductor along the second path, and a second resistor along the second path. In some embodiments, the capacitor and inductor may be configured to provide control of the phase of either or both of the first and second portions, and the first and second resistors may be configured to provide control of the amplitude of either or both of the first and second portions.

In some embodiments, the tunable input circuit may include a balun-based circuit. In some embodiments, the balun-based circuit may include a balun having a first node configured to receive an input signal, a second node coupled to a carrier amplifier via a first resistor, a third node coupled to a peaking amplifier via a second resistor, and a fourth node coupled to a ground potential via a termination impedance. The balun-based circuit may further include a first capacitor coupled between the first node and a third node, and a second capacitor coupled between the second node and a fourth node. In some embodiments, the balun may include a first inductor coupled between the first node and the second node, and a second inductor coupled between the third node and the fourth node.

In some embodiments, the input network may further include a controller configured to tune the tunable input network. In some embodiments, the controller may be configured to tune the tunable input network based on a frequency of the RF signal. In some embodiments, the controller may be configured to tune the tunable input network such that the amplitude of the first portion and the amplitude of the second portion are not equal. In some embodiments, the controller may be configured to tune the tunable input network such that the phase of the first portion and the phase of the second portion are non-orthogonal. In some embodiments, the controller may be configured to tune the tunable input network such that harmonics generated by the carrier amplifier and harmonics generated by the peaking amplifier are cancelled by the combiner. In some embodiments, the controller may be configured to perform wideband linearization of the doherty power amplifier.

In certain embodiments, the present disclosure relates to a doherty power amplifier module including a package substrate configured to house a plurality of components. The doherty power amplifying module includes a doherty PA system implemented on a package substrate. The doherty PA system includes a splitter circuit configured to receive a Radio Frequency (RF) signal and to split the RF signal into a first portion along a first path and a second portion along a second path. The doherty PA system includes a tunable input circuit implemented along either or both of the first and second paths. The tunable input circuit is configured to provide control of amplitude and phase of either or both of the first and second portions. The doherty PA system includes a carrier amplifier configured to amplify the first portion and a peak amplifier configured to amplify the second portion. The doherty PA includes an output circuit configured to combine the outputs of the carrier amplifier and the peak amplifier to produce an amplified RF signal.

In some embodiments, the output circuit comprises a tunable impedance circuit.

In certain embodiments, the present disclosure relates to a wireless device comprising a transceiver configured to generate a Radio Frequency (RF) signal. The wireless device includes a Power Amplifier (PA) module in communication with the transceiver. The PA module includes a package substrate configured to house a plurality of components and a PA system implemented on the package substrate. The PA system includes a splitter circuit configured to receive a Radio Frequency (RF) signal and to split the RF signal into a first portion along a first path and a second portion along a second path. The PA system includes a tunable input circuit implemented along either or both of the first path and the second path. The tunable input circuit is configured to provide control of amplitude and phase of either or both of the first and second portions. The PA system includes a carrier amplifier configured to amplify the first portion and a peaking amplifier configured to amplify the second portion. The PA system includes an output circuit configured to combine the outputs of the carrier amplifier and the peaking amplifier to produce an amplified RF signal. The wireless device also includes an antenna in communication with the PA module. The antenna is configured to facilitate transmission of the amplified RF signal.

For purposes of summarizing the disclosure, certain aspects, advantages, and novel features of the invention have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

Drawings

Fig. 1 shows an example configuration of a doherty power amplifier.

Fig. 2 illustrates that, in some embodiments, the tunable input network may include an RC circuit.

Fig. 3 illustrates that, in some embodiments, the tunable input network may include RLC circuitry.

Fig. 4 illustrates that, in some embodiments, the tunable input network may include balun-based circuitry.

Fig. 5 depicts a module having one or more features as described herein.

Fig. 6 depicts a wireless device having one or more features as described herein.

Detailed Description

The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed invention.

Fig. 1 shows an example configuration of a doherty power amplifier 100. The example power amplifier 100 is shown to include an input port (RF _ IN) for receiving an RF signal to be amplified. Such an input RF signal may be partially amplified by the pre-driver amplifier 102 before being split (e.g., by the splitter 104) into the carrier amplification path 110 and the peaking amplification path 130.

In fig. 1, the carrier amplification path 110 is shown as including a phase shifter 112, an attenuator 113, and an amplification stage, collectively indicated at 114. The amplification stage 114 is shown as including a driver stage 116 and an output stage 120. The driver stage 116 is shown as biased by a driver bias circuit 118 and the output stage 120 is shown as biased by an output bias circuit 122. In some embodiments, there may be more or less amplification stages. In the various examples described herein, the amplification stage 114 is sometimes described as an amplifier; however, it will be appreciated that such an amplifier may comprise one or more stages.

In fig. 1, the peak amplification path 130 is shown as including a phase shifter 132, an attenuator 133, and an amplification stage, collectively indicated at 134. The amplifier stage 134 is shown as including a driver stage 136 and an output stage 140. The driver stage 136 is shown biased by a driver bias circuit 138, and the output stage 140 is shown biased by an output bias circuit 142. In some embodiments, there may be more or less amplification stages. In the various examples described herein, the amplification stage 134 is sometimes described as an amplifier; however, it will be appreciated that such an amplifier may comprise one or more stages.

As further shown in fig. 1, carrier amplification path 110 and peaking amplification path 130 may be combined by combiner 144 to produce an amplified RF signal at an output port (RF-OUT). In some embodiments, combiner 144 includes a tunable impedance circuit. Examples relating to COMBINER 144 are described in more detail in U.S. patent application No.14/824,856 entitled "doherty amplitude communications WITH TUNABLE impact communications CIRCUIT" filed on 12.8.2015 and hereby incorporated by reference in its entirety.

In some doherty PA implementations, the inputs to the carrier amplifier 114 and the peaking amplifier 134 are equal in amplitude and in quadrature in phase to ensure that the load line is modulated according to the output power to result in high efficiency at back-off. However, such an implementation may suffer from high AM-AM and AM-PM distortion, which is typically caused by a rapid turn-off of the peak amplifier 134, which causes the carrier amplifier 114 load line to dynamically change.

Sudden changes in the load line of the carrier amplifier 114 and the resulting changes to the current through the carrier amplifier 114 may cause the inherent parasitics (e.g., collector-base and base-emitter capacitances of transistors within the carrier amplifier 114) to drastically change. Such altered non-linear properties may cause AM-AM and AM-PM distortions.

In wideband doherty PAM, the frequency response of the combiner 144 and splitter 104 may cause such AM-AM and AM-PM distortions to have a frequency dependence. Thus, in certain embodiments, increased linearity may be obtained by using a tunable input network 160 (also referred to as a programmable input network).

The tunable input network 160 includes a controller 162 that tunes the phase shifters 112, 132 and attenuators 113, 133 of each path so that the inputs to the carrier amplifier 114 and the peak amplifier 134 are not equal in magnitude and are not orthogonal in phase.

The controller 162 may control the attenuators 113, 133 of each path to vary the amplitude of the signals input to the carrier amplifier 114 and the peak amplifier 134. Specifically, the controller 162 may control the attenuators 113, 133 of each path so that the output current of the carrier amplifier 114 and the output current of the peak amplifier 134 are in an appropriate proportion over a wide range of frequencies. The controller 162 can ensure that the carrier amplifier 114 and the peaking amplifier 134 have the same dynamic load line over a wide range of frequencies, which eliminates the frequency dependence of the AM-AM and AM-PM distortions. To this end, the controller 162 may control the attenuator 113, 133 of each path based on the frequency of the signal received at the input port (e.g., based on a control signal indicative of the frequency of the input signal).

When the collector-base and base-emitter capacitances of the transistors of the carrier amplifier 114 and the peaking amplifier 134 change due to the dynamic load line, the phase response of the carrier amplifier 114 and the peaking amplifier 134 changes. The controller 162 may control the phase shifters 112, 132 of each path to change the relative phase of the signals input to the carrier amplifier 114 and the peak amplifier 134. In particular, the controller 162 may control the phase shifters 112, 132 of each path such that the overall carrier amplifier 114 and peak amplifier 134 transfer functions (from the input of the phase shifters to the output of the amplifiers) remain substantially constant over frequency. The controller 162 may control the phase shifters 112, 132 of each path in a suitable manner to cancel the AM-AM and AM-PM distortions. To this end, the controller 162 may control the phase shifter 112, 132 of each path based on the frequency of the signal received at the input port (e.g., based on a control signal indicative of the frequency of the input signal).

Thus, the controller 162 can linearize the doherty power amplifier 100 by approximately controlling the amplitude and phase differences of the inputs to the carrier amplifier 114 and the peak amplifier 134 to ensure that the carrier amplifier 114 harmonics and the peak amplifier 134 harmonics are at the proper amplitude and phase to be cancelled out in the final combined doherty PAM output. By controlling the amplitude and phase of the harmonics from the input, the doherty power amplifier can use low-Q, low-breakdown components, resulting in cost-effectiveness. By maintaining appropriate amplitude and phase differences over a wide range of frequencies via the controller of the tunable input network, controller 162 can compensate for any effects on the distortion mechanism caused by the frequency response of splitter 104 and/or combiner 144.

Fig. 2 illustrates that, in some embodiments, the tunable input network 260 may include an RC circuit. The tunable input network 260 includes: an input node 201 configured to receive an input signal; a carrier output node 202 configured to output a first portion of an input signal (e.g., a carrier signal) to a carrier amplifier; and a peak output node 203 configured to output a second portion of the input signal (e.g., a peak signal) to the peak amplifier.

The tunable input network 260 includes a first path from the input node 201 to the carrier output node 202 and a second path from the input node 201 to the peak output node 203. The tunable input network 260 includes a first capacitor 211 along a first path, a first resistor 212 in a shunt (shunt) configuration between the first capacitor 211 and the carrier output node 202, a second resistor 221 along a second path, and a second capacitor 222 in a shunt configuration between the second resistor 221 and the peak output node 203.

The first capacitor 211, the first resistor 212, the second capacitor 222 and the second resistor 221 are each tunable. In certain embodiments, the first and second capacitors 211, 222 each comprise a switchable capacitor bank, and the first and second resistors 212, 221 each comprise a switchable resistor bank.

The capacitances of the first and second capacitors 211 and 222, and the resistances of the first and second resistors 212 and 221 may be controlled (e.g., by a controller) to vary the amplitude and phase of the carrier and peak signals. In particular, the carrier signal and the peak signal may be unequal in magnitude and non-orthogonal in phase.

Fig. 3 illustrates that in some embodiments, tunable input network 360 may include RLC circuitry. The tunable input network 360 includes: an input node 301 configured to receive an input signal; a carrier output node 302 configured to output a first portion of an input signal (e.g., a carrier signal) to a carrier amplifier; and a peak output node 303 configured to output a second portion of the input signal (e.g., a peak signal) to the peak amplifier.

Tunable input network 360 includes a first path from input node 301 to carrier output node 302 and a second path from input node 301 to peak output node 303. The tunable input network 360 includes a capacitor 311 along a first path, a first resistor 312 along the first path, an inductor 321 along a second path, and a second resistor 322 along the second path.

The capacitor 311, the first resistor 312 and the second resistor 322 are each tunable. In some embodiments, inductor 321 is tunable. In certain embodiments, the capacitor 311 comprises a switchable capacitor bank, and the first resistor 312 and the second resistor 322 each comprise a switchable resistor bank.

The capacitance of the capacitor 311 may be controlled (e.g., by a controller) to change the relative phases of the carrier signal and the peak signal. In particular, the carrier signal and the peak signal may be non-orthogonal in phase. The resistances of the first resistor 312 and the second resistor 322 may be controlled (e.g., by a controller) to vary the amplitudes of the carrier signal and the peak signal. In particular, the carrier signal and the peak signal may be unequal in amplitude.

Fig. 4 illustrates that in some embodiments, tunable input network 460 may include balun-based circuitry. The tunable input network 460 includes: an input node 460 configured to receive an input signal; a carrier output node 402 configured to output a first portion of an input signal (e.g., a carrier signal) to a carrier amplifier; and a peak output node 403 configured to output a second portion of the input signal (e.g., a peak signal) to the peak amplifier.

The tunable input network 460 includes a first path from the input node 401 to the carrier output node 402 and a second path from the input node 401 to the peak output node 403. The tunable input network 460 includes a balun 420 having a first node coupled to the input node 401 and configured to receive an input signal, a second node coupled to the carrier output node 402 via a first resistor 421, a third node coupled to the peak output node 403 via a second resistor 422, and a fourth node coupled to a ground potential via a termination impedance 423. The tunable input network 460 also includes a first capacitor 411 coupled between the first node of the balun 420 and the third node of the balun 420, and a second capacitor 412 coupled between the second node of the balun 420 and the fourth node of the balun 420. The balun 420 includes a first inductor coupled between a first node and a second inductor coupled between a third node and a fourth node.

The first capacitor 411, the second capacitor 412, the first resistor 421 and the second resistor 422 are each tunable. In some embodiments, the termination impedance 423 is tunable. In certain embodiments, the first and second capacitors 411, 412 each comprise a switchable capacitor bank, and the first and second resistors 421, 422 each comprise a switchable resistor bank.

The capacitances of the first and second capacitors 411 and 412, and the resistances of the first and second resistors 421 and 422 can be controlled (e.g., by a controller) to vary the amplitude and phase of the carrier and peak signals. In particular, the carrier signal and the peak signal may be unequal in magnitude and non-orthogonal in phase.

Fig. 5 illustrates that, in some embodiments, some or all of the configurations (e.g., the configurations shown in fig. 1-4) may be implemented in whole or in part in modules. Such a module may be, for example, a Front End Module (FEM). In the example of fig. 5, module 500 may include a package substrate 502, and many components may be mounted on such package substrate 502. For example, the FE-PMIC component 504, the power amplifier assembly 506 (which may include the tunable input network 507), the matching component 508, and the multiplexer assembly 510 may be mounted and/or implemented on and/or within the package substrate 502. Other components, such as a number of SMT devices 514 and Antenna Switch Modules (ASMs) 512, may also be mounted on the package substrate 502. While all of the various components are depicted as being laid out on the package substrate 502, it will be understood that some components may be implemented on top of other components.

In certain embodiments, devices and/or circuits having one or more of the features described herein may be included in RF electronic devices, such as wireless devices. Such devices and/or circuits may be implemented directly in a wireless device, in a modular form as described herein, or in some combination thereof. In some embodiments, such wireless devices may include, for example, cellular telephones, smart phones, handheld wireless devices with or without telephone functionality, wireless tablets, and the like.

Fig. 6 depicts an example wireless device 600 having one or more of the beneficial features described herein. In the context of a module having one or more features as described herein, such a module may be generally depicted by dashed box 500 and may be implemented, for example, as a Front End Module (FEM).

Referring to fig. 6, Power Amplifiers (PAs) 60a-60d may receive their respective RF signals from transceiver 610, and transceiver 610 may be configured and operated in a well-known manner to generate RF signals to be amplified and transmitted, and to process the received signals. A transceiver 610 is shown interacting with the baseband subsystem 608, with the baseband subsystem 608 configured to provide conversion between user-appropriate data and/or voice signals and RF signals appropriate for the transceiver 610. Transceiver 610 may also be in communication with a power management component 606, power management component 606 being configured to manage power for operation of wireless device 600. Such power management may also control the operation of the baseband subsystem 608 and the module 500.

The baseband subsystem 608 is shown connected to the user interface 602 to facilitate various inputs and outputs of voice and/or data provided to and received from a user. The baseband subsystem 608 may also be connected to memory 604 configured to store data and/or instructions to facilitate operation of the wireless device and/or to provide storage of information for a user.

In the example wireless device 600, the outputs of the PAs 60a-60d are shown as being matched (via respective matching circuits 620a-620d) and routed to their respective duplexers 612a-612 d. Such amplified and filtered signals may be routed through antenna switch 614 to antenna 616 (or multiple antennas) for transmission. In some embodiments, duplexers 612a-612d may allow transmit and receive operations to be performed simultaneously using a common antenna (e.g., 616). In fig. 6, the received signal is shown as being routed to an "Rx" path (not shown) that may include, for example, a Low Noise Amplifier (LNA).

Many other wireless device configurations may utilize one or more of the features described herein. For example, the wireless device need not be a multi-band device. In another example, the wireless device may include additional antennas, such as diversity antennas, and additional connection line features, such as Wi-Fi, bluetooth, and GPS.

Throughout this specification and claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, unless the context clearly requires otherwise; i.e., in the sense of "including, but not limited to". The term "coupled," as used generally herein, refers to two or more elements that may be connected directly or through one or more intervening elements. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above detailed description using the singular or plural number may also include the plural or singular number respectively. The word "or" when referring to a list of two or more items covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

The above detailed 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 of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, while processes or blocks are presented in a given order, alternative embodiments may perform routines having steps, or use systems having blocks, 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 number of different ways. Likewise, although processes or blocks are sometimes shown as being performed in series, these processes or blocks may alternatively be performed in parallel, or may be performed at different times.

The teachings of the invention provided herein may be applied to other systems and need not be applied to the systems described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments.

While certain embodiments of the present invention have been described, these embodiments have been 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 many other forms; further, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.

Claims (20)

1. An input network for a doherty power amplifier, the input network comprising:

a splitter circuit configured to receive a Radio Frequency (RF) signal and to branch the RF signal into a first portion along a first path to a carrier amplifier of a Doherty power amplifier and a second portion along a second path to a peak amplifier of the Doherty power amplifier; and

a tunable input circuit implemented along either or both of the first path and the second path, the tunable input circuit configured to provide control of amplitude and phase of either or both of the first portion and the second portion.

2. The input network of claim 1, wherein the tunable input circuit comprises an RC circuit.

3. The input network of claim 2, wherein the RC circuit comprises a first capacitor along a first path, a first resistor in a bypass configuration between the first capacitor and the carrier amplifier, a second resistor along a second path, and a second capacitor in a bypass configuration between the second resistor and the peaking amplifier.

4. The input network of claim 3, wherein the first capacitor, first resistor, second capacitor, and second resistor are each tunable.

5. The input network of claim 4, wherein the first and second capacitors each comprise a switchable capacitor bank and the first and second resistors each comprise a switchable resistor bank.

6. The input network of claim 1 wherein the tunable input circuit comprises an RLC circuit.

7. The input network of claim 6 wherein the RLC circuit includes a capacitor along a first path, a first resistor along a first path, an inductor along a second path, and a second resistor along a second path.

8. The input network of claim 7, wherein the capacitors and inductors are configured to provide control of a phase of either or both of the first and second portions, and the first and second resistors are configured to provide control of an amplitude of either or both of the first and second portions.

9. The input network of claim 1, wherein the tunable input circuit comprises a balun-based circuit.

10. The input network of claim 9, wherein the balun-based circuit comprises a balun having a first node configured to receive an input signal, a second node coupled to a carrier amplifier via a first resistor, a third node coupled to a peaking amplifier via a second resistor, and a fourth node coupled to a ground potential via a termination impedance, the balun-based circuit further comprising a first capacitor coupled between the first node and the third node and a second capacitor coupled between the second node and the fourth node.

11. The input network of claim 10, wherein the balun includes a first inductor coupled between a first node and a second inductor coupled between a third node and a fourth node.

12. The input network of claim 1, further comprising a controller configured to tune the tunable input network.

13. The input network of claim 12, wherein the controller is configured to tune the tunable input network based on a frequency of the RF signal.

14. The input network of claim 12, wherein the controller is configured to tune the tunable input network such that the amplitude of the first portion and the amplitude of the second portion are not equal.

15. The input network of claim 12, wherein the controller is configured to tune the tunable input network such that the phase of the first portion and the phase of the second portion are non-orthogonal.

16. The input network of claim 12, wherein the controller is configured to tune the tunable input network such that harmonics generated by a carrier amplifier and harmonics generated by a peaking amplifier are cancelled by a combiner.

17. The input network of claim 12 wherein the controller is configured to perform wideband linearization of the doherty power amplifier.

18. A doherty Power Amplifier (PA) module comprising:

a package substrate configured to accommodate a plurality of components; and

a doherty PA system implemented on the package substrate, the doherty PA system comprising: splitter circuitry configured to receive a Radio Frequency (RF) signal and to split the RF signal into a first portion along a first path and a second portion along a second path; a tunable input circuit implemented along either or both of a first path and a second path, the tunable input circuit configured to provide control of amplitude and phase of either or both of the first portion and the second portion; a carrier amplifier configured to amplify the first portion; a peak amplifier configured to amplify the second portion; and an output circuit configured to combine the outputs of the carrier amplifier and the peak amplifier to produce an amplified RF signal.

19. The doherty PA module of claim 18 wherein the output circuit includes a tunable impedance circuit.

20. A wireless device, comprising:

a transceiver configured to generate a Radio Frequency (RF) signal;

a Power Amplifier (PA) module in communication with the transceiver, the PA module including a package substrate configured to house a plurality of components and a PA system implemented on the package substrate, the PA system including: splitter circuitry configured to receive a Radio Frequency (RF) signal and to split the RF signal into a first portion along a first path and a second portion along a second path; a tunable input circuit implemented along either or both of a first path and a second path, the tunable input circuit configured to provide control of amplitude and phase of either or both of the first portion and the second portion; a carrier amplifier configured to amplify the first portion; a peak amplifier configured to amplify the second portion; and an output circuit configured to combine the outputs of the carrier amplifier and the peaking amplifier to produce an amplified RF signal; and

an antenna in communication with the PA module, the antenna configured to facilitate transmission of the amplified RF signal.