Power amplifier system, portable device, and amplification method in mobile phone

Abstract

To provide a load modulated Doherty power amplifier that can operate with extremely high power added efficiency (PAE) over a wide dynamic range.SOLUTION: A load modulated Doherty power amplifier 20 includes a combiner 14, a carrier amplifier 1 having an output coupled to a first terminal of the combiner, a peaking amplifier having an output coupled to a second terminal of the combiner, a load modulating amplifier having an output coupled to a third terminal of the combiner, and a radio frequency (RF) output port that is coupled to a fourth terminal of the combiner and provides an RF output signal. The peaking amplifier is operable to activate at a first power threshold, while the load modulating amplifier is operable to activate at a second power threshold to modulate down a load of the carrier amplifier and of the peaking amplifier.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] Embodiments of the present invention relate to electronic systems, and more specifically to radio frequency (RF) electronic equipment. [Background technology]

[0002] In RF communication systems, power amplifiers are used to amplify RF signals for transmission via antennas.

[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, customer premises equipment (CPE), laptops, and wearable electronic devices. For example, in wireless devices communicating using cellular standards, wireless local area network (WLAN) standards, and / or any other suitable communication standards, power amplifiers can be used for the purpose of amplifying RF signals. RF signals may have frequencies in the range of approximately 30 kHz to 300 GHz, such as in the range of approximately 425 MHz to approximately 7.125 GHz for frequency range 1 (FR1) of the fifth-generation (5G) communication standard, or in the range of approximately 24.250 GHz to approximately 52.600 GHz for frequency range 2 (FR2) of the 5G communication standard. [Overview of the project]

[0004] In a given embodiment, the disclosure relates to a power amplifier system. The power amplifier system includes a coupler, the coupler includes a first terminal, a second terminal, a third terminal and a fourth terminal, and the coupler is configured to provide a radio frequency output signal from the fourth terminal. The power amplifier system further includes a carrier amplifier including an output section coupled to the first terminal of the coupler, a peak amplifier including an output section coupled to the second terminal of the coupler, and a load modulation amplifier including an output coupled to the third terminal of the coupler.

[0005] In some embodiments, the peak amplifier is configured to be active at a first power threshold, and the load modulation amplifier is configured to be active at a second power threshold greater than the first power threshold. According to various embodiments, once the load modulation power amplifier is activated, it becomes operable to modulate down the loads of the carrier amplifier and the peak amplifier. According to some embodiments, the carrier amplifier includes a saturation detector configured to monitor the saturation level of the carrier amplifier, and the saturation detector is operable to control the activation of the peak amplifier and the activation of the load modulation amplifier. According to certain embodiments, the carrier amplifier includes a Class AB bias circuit, the peak amplifier includes a first Class C bias circuit, and the load modulation amplifier includes a second Class C bias circuit.

[0006] In various embodiments, the load modulation amplifier includes a cascode amplifier stage. According to certain embodiments, the carrier amplifier includes a first common-emitter amplifier stage, and the peak amplifier includes a second common-emitter amplifier stage.

[0007] In some embodiments, the coupler is a hybrid coupler, where the first terminal corresponds to a zero-degree port, the second terminal to a 90-degree port, the third terminal to an isolation port, and the fourth terminal to a common port.

[0008] In some embodiments, the power amplifier system further includes an input divider configured to divide a radio frequency input signal into a plurality of input signal components, including a first input signal component supplied to the input of a carrier amplifier and a second input signal component supplied to the input of a peak amplifier. According to certain embodiments, the plurality of input signal components further include a third input signal component supplied to the input of a load modulation amplifier.

[0009] In a given embodiment, the disclosure relates to a portable device. The portable device includes an antenna configured to transmit a radio frequency output signal and a front-end system. The front-end system includes a power amplifier system, which includes a coupler, a carrier amplifier having an output section coupled to a first terminal of the coupler, a peak amplifier having an output section coupled to a second terminal of the coupler, and a load modulation amplifier having an output section coupled to a third terminal of the coupler, the coupler being configured to provide a radio frequency output signal at a fourth terminal.

[0010] In various embodiments, the peak amplifier is configured to be active at a first power threshold, and the load modulation amplifier is configured to be active at a second power threshold greater than the first power threshold. According to various embodiments, once the load modulation power amplifier is activated, it becomes operable to downmodulate the loads of the carrier amplifier and the peak amplifier. According to some embodiments, the carrier amplifier includes a saturation detector configured to monitor the saturation level of the carrier amplifier, and the saturation detector is operable to control the activation of the peak amplifier and the activation of the load modulation amplifier. According to certain embodiments, the carrier amplifier includes a Class AB bias circuit, the peak amplifier includes a first Class C bias circuit, and the load modulation amplifier includes a second Class C bias circuit.

[0011] In various embodiments, the load modulation amplifier includes a cascode amplifier stage. According to some embodiments, the carrier amplifier includes a first common-emitter amplifier stage, and the peak amplifier includes a second common-emitter amplifier stage.

[0012] In certain embodiments, the coupler is a hybrid coupler, where the first terminal corresponds to a zero-degree port, the second terminal to a 90-degree port, the third terminal to an isolation port, and the fourth terminal to a common port.

[0013] In some embodiments, the portable device includes an input divider configured to divide a radio frequency input signal into multiple input signal components, including a first input signal component supplied to the input of a carrier amplifier and a second input signal component supplied to the input of a peak amplifier. According to certain embodiments, the multiple input signal components further include a third input signal component supplied to the input of a load modulation amplifier.

[0014] In a given embodiment, the present disclosure relates to a method of amplification in a mobile phone. The method includes providing a first radio frequency signal from the output of a carrier amplifier to a first terminal of a coupler; providing a first radio frequency signal from the output of a peak amplifier to a second terminal of a coupler; providing a first radio frequency signal from the output of a load modulation amplifier to a third terminal of a coupler; combining the first radio frequency signal, a second radio frequency signal, and a third radio frequency signal using the coupler to generate a radio frequency output signal; and providing the radio frequency output signal at a fourth terminal of the coupler.

[0015] In various embodiments, the method further includes activating a peak amplifier at a first power threshold and activating a load modulation amplifier at a second power threshold greater than the first power threshold. According to certain embodiments, activating the load modulation amplifier includes downmodulating the loads of the carrier amplifier and the peak amplifier. [Brief explanation of the drawing]

[0016] Embodiments of the present disclosure are described below through non-limiting examples with reference to the accompanying drawings.

[0017] [Figure 1] This is a schematic diagram of a load-modulated Doherty power amplifier according to one embodiment. [Figure 2] This is a schematic diagram of a load-modulated Doherty power amplifier according to another embodiment. [Figure 3] This is a schematic diagram of a load-modulated Doherty power amplifier according to another embodiment. [Figure 4]Schematic diagram of a load modulation Doherty power amplifier of another embodiment. [Figure 5] Schematic diagram of a load modulation Doherty power amplifier of another embodiment. [Figure 6] Schematic diagram of a load modulation Doherty power amplifier of another embodiment. [Figure 7] Graph of an example of the gain versus output power of a load modulation Doherty power amplifier. [Figure 8] Graph of an example of the power added efficiency (PAE) versus output power of a load modulation Doherty power amplifier. [Figure 9] Graph of another example of the PAE versus output power of a load modulation Doherty power amplifier. [Figure 10] Schematic diagram of a mobile device of one embodiment. [Figure 11] Schematic diagram of a power amplifier system according to another embodiment. [Figure 12A] Schematic diagram of a package module of one embodiment. [Figure 12B] Schematic diagram of a cross-section of the package module along the line 12B-12B of FIG. 12A. **DETAILED DESCRIPTION OF THE INVENTION**

[0018] The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in many different manners, for example, as defined and covered by the claims. In this specification, drawings are referred to in which the same reference numerals indicate the same or functionally similar elements. It is understood that the elements shown in the drawings are not necessarily 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 shown in the drawings. Further, some embodiments may include any suitable combination of features from two or more of the drawings.

[0019] The linearity of a power amplifier is directly related to the level of gain compression within the power amplifier. That is, a power amplifier can be designed with a fixed supply voltage that defines the target load impedance for acceptable linearity.

[0020] In certain applications, such as portable handsets, the load presented to the power amplifier can fluctuate significantly depending on the operating environment. For example, the voltage standing wave ratio (VSWR) of the antenna, and consequently the load on the power amplifier, can vary based on how the portable handset is handled by the user. These load fluctuations can degrade the linearity and / or spectral performance of the power amplifier.

[0021] One type of power amplifier is a Doherty power amplifier, which includes a main amplifier or carrier amplifier and an auxiliary amplifier or peak amplifier that work together to amplify an RF signal. The Doherty power amplifier combines the carrier signal from the carrier amplifier and the peak signal from the peak amplifier to produce an amplified RF output signal. In a given implementation example, the carrier amplifier is enabled over a wide range of power levels (e.g., by a Class AB bias circuit), while the peak amplifier is selectively enabled at high power levels (e.g., by a Class C bias circuit).

[0022] Such Doherty power amplifiers operate efficiently at 6 dB power backoff, but suffer from inefficiency at lower power levels for very high peak-to-average power ratio (PAPR) waveforms and / or if the output power is not sufficiently centered on the peak of the amplifier's power-dependent efficiency profile. For example, in advanced modulation schemes with high PAPR (e.g., 5 G waveforms), the amplifier needs to operate at several dB above the maximum saturation output power (Psat) to maintain linearity.

[0023] Furthermore, the linearity of Doherty power amplifiers is particularly susceptible to degradation in the presence of load fluctuations. For example, the amplitude distortion (AM / AM) of a carrier amplifier is a function of the voltage standing wave ratio (VSWR) of the load, while the AM / AM of a peak amplifier is typically a function of the input power, which is uncorrelated with the VSWR of the load.

[0024] A load-modulated Doherty power amplifier is provided herein. In a given embodiment, the load-modulated Doherty power amplifier includes a coupler, a carrier amplifier having an output section coupled to a first terminal of the coupler, a peak amplifier having an output section coupled to a second terminal of the coupler, a load-modulated amplifier having an output section coupled to a third terminal of the coupler, and an RF output port coupled to a fourth terminal of the coupler to provide an RF output signal. The peak amplifier is operable to be active at a first power threshold, while the load-modulated amplifier is operable to be active at a second power threshold, and the loads of the carrier amplifier and the peak amplifier are downmodulated.

[0025] For example, in one implementation, only the carrier amplifier is activated up to approximately 24 dBm of the input signal power. Additionally, both the carrier amplifier and the peak amplifier are activated from approximately 24 dBm to 30 dBm of the input signal power, operating in Doherty mode (as a Doherty amplifier). Furthermore, above approximately 30 dBm of the input signal power, the load modulation amplifier is activated, and the output power increases as the load on the Doherty amplifier is reduced.

[0026] Such load-modulated Doherty power amplifiers can operate with extremely high power added efficiency (PAE) over a wide dynamic range. In one example, a rated PAE of over 58% is achieved over a dynamic range of 9 dB.

[0027] In addition to providing high PAE over a wide dynamic range, load-modulated Doherty power amplifiers exhibit a number of other advantages, including, but not limited to, robust phase performance of the peak amplifier, the ability to independently control the harmonic termination of the carrier and peak amplifiers, and / or excellent power amplification characteristics over a wide range of signal types and frequency ranges.

[0028] In a given implementation example, the coupler is implemented as a 3dB hybrid coupler. Additionally, the output impedance of the load modulation amplifier can be scaled to approximately -jX, where X is the characteristic impedance of the coupler. Before the load modulation amplifier is turned on, the power amplifier operates in a manner similar to that of a Doherty amplifier. However, once the Doherty amplifier obtains approximately equal power contributions from the carrier amplifier path and the peak amplifier path, the load modulation amplifier turns on and modulates the load of the Doherty power amplifier to a lower impedance, achieving high output power (e.g., about 5dB higher power).

[0029] Load-modulated Doherty power amplifiers may be included in a wide variety of RF communication systems, including but not limited to base stations, network access points, mobile phones, tablets, customer premises equipment (CPE), laptops, computers, wearable electronic devices, and / or other communication devices.

[0030] Figure 1 is a schematic diagram of one embodiment of a load-modulated Doherty power amplifier 10. The load-modulated Doherty power amplifier 10 includes a carrier amplifier 1, a peak amplifier 2, a load modulation amplifier 3, and a coupler 4 (implemented in this embodiment as a 3dB hybrid coupler).

[0031] In the illustrated embodiment, the coupler 4 includes a first terminal (in this example, a through port or 0° port), a second terminal (in this example, a coupling port or 90° port), a third terminal (in this example, an isolation port or ISO port), and a fourth terminal (in this example, a common port or COM port). As shown in Figure 1, the 0° port is connected to the output of the carrier amplifier 1, the 90° port is coupled to the output of the peak amplifier 2, the ISO port is coupled to the output of the load modulation amplifier 3, and the COM port is connected to the RF output of the load modulation Doherty power amplifier 10. OUT It will be joined to

[0032] Carrier amplifier 1 and peak amplifier 2 operate to amplify components of the RF input signal. The RF input signal components amplified by carrier amplifier 1 and peak amplifier 2 may have a phase difference or delay. For example, in a given implementation example, an input splitter (e.g., another 3dB hybrid coupler) outputs a pair of RF input signal components with approximately 90 degrees of separation, and these pair of RF input signal components are amplified by carrier amplifier 1 and peak amplifier 2. In a given implementation example, load modulation amplifier 3 also receives signal components of the RF input signal.

[0033] Continuing to refer to Figure 1, the peak amplifier 2 can be operated to become active at the first power threshold, while the load modulation amplifier 3 can be operated to become active at the second power threshold in order to modulate down the load of the carrier amplifier 1 and the peak amplifier 2. The second power threshold is greater than the first power threshold.

[0034] For example, in one implementation, only carrier amplifier 1 is activated up to approximately 24 dBm of the input signal power. Additionally, both carrier amplifier 1 and peak amplifier 2 are activated from approximately 24 dBm to 30 dBm of the input signal power, operating in Doherty mode (as Doherty amplifiers). Furthermore, above approximately 30 dBm of the input signal power, load modulation amplifier 3 is activated, and the output power increases as the load on the Doherty amplifier is reduced.

[0035] The coupler 4 combines the amplified RF input signal components and outputs to the RF output section. OUT It generates an amplified RF output signal that is supplied to it.

[0036] The load-modulated Doherty power amplifier 10 offers a number of advantages, including, but not limited to, a high PAE over a wide dynamic range. In one example, a rated PAE of over 58% is achieved over a dynamic range of 9 dB. That is, the load-modulated Doherty power amplifier 10 is well-suited for amplifying composite waveforms with high PAPR, such as 5G waveforms.

[0037] Figure 2 is a schematic diagram of a load-modulated Doherty power amplifier 20 of another embodiment. The load-modulated Doherty power amplifier 20 includes a carrier amplifier 1, a peak amplifier 2, a load modulation amplifier 3, and a 3dB hybrid coupler 14.

[0038] The load-modulated Doherty power amplifier 20 in Figure 2 is similar to the load-modulated Doherty power amplifier 10 in Figure 1, but differs in that the load-modulated Doherty power amplifier 20 shows a specific implementation example of the coupler.

[0039] More specifically, the 3dB hybrid coupler 14 in Figure 2 includes a first winding 16a and a second winding 16b that are electromagnetically coupled to each other. Additionally, the first winding 16a is connected between the 0° port and the COM port, while the second winding 16b is connected between the ISO port and the 90° port. The 3dB hybrid coupler 14 further includes a first capacitor C1 connected between the 0° port and the ISO port, a second capacitor C2 connected between the COM port and the 90° port, and a third capacitor C3 connected between the ISO port and the ground voltage.

[0040] Figure 3 is a schematic diagram of a load-modulated Doherty power amplifier 30 of another embodiment. The load-modulated Doherty power amplifier 30 includes a carrier amplifier 1, a peak amplifier 2, a load modulation amplifier 3, a coupler 4, and an input splitter 25.

[0041] The load-modulated Doherty power amplifier 30 in Figure 3 is similar to the load-modulated Doherty power amplifier 10 in Figure 1, but the load-modulated Doherty power amplifier 30 further has an RF input section RF IN The difference is that it includes an input splitter 25 that splits the RF input signal received from the device into a first RF input signal component amplified by the carrier amplifier 1 and a second RF input signal component amplified by the peak amplifier 2. In this example, the input splitter 25 includes a phase shifter 26 that delays the second RF input signal component by approximately 90° compared to the first RF input signal. Although not shown in Figure 3, in a given implementation example, the RF input splitter 25 further generates a third RF input signal component for the load modulation power amplifier 3.

[0042] Figure 4 is a schematic diagram of a load-modulated Doherty power amplifier 40 of another embodiment. The load-modulated Doherty power amplifier 40 includes a carrier amplifier 31, a peak amplifier 32, a load modulation amplifier 33, and a coupler 4.

[0043] The load-modulated Doherty power amplifier 40 in Figure 4 is similar to the load-modulated Doherty power amplifier 10 in Figure 1, but differs in that the load-modulated Doherty power amplifier 40 shows multiple specific implementation examples of amplifier bias.

[0044] More specifically, in the embodiment shown in Figure 4, the carrier amplifier 31 includes a Class AB bias circuit 35, the peak amplifier 32 includes a Class C bias circuit 36, and the load modulation amplifier 33 includes a deep Class C bias circuit 37 that is active at a higher power threshold than the Class C bias circuit 36. Although one embodiment of biasing for a load-modulated Doherty power amplifier is shown, the teachings herein are applicable to other implementations of biasing.

[0045] Figure 5 is a schematic diagram of a load-modulated Doherty power amplifier 50 of another embodiment. The load-modulated Doherty power amplifier 50 includes a carrier amplifier 41, a peak amplifier 42, a load modulation amplifier 43, and a coupler 4.

[0046] The load-modulated Doherty power amplifier 50 in Figure 5 is similar to the load-modulated Doherty power amplifier 10 in Figure 1, but differs in that the load-modulated Doherty power amplifier 50 shows multiple specific implementation examples of amplifier bias.

[0047] More specifically, the carrier amplifier 41 includes a saturation detector 45 for detecting saturation of the carrier amplifier 41. Additionally, the peak amplifier 42 includes a first controllable bias current source 46 controlled by a first control signal from the saturation detector 45, while the load modulation amplifier 43 includes a second controllable bias current source 47 controlled by a second control signal from the saturation detector 45.

[0048] When the carrier amplifier 41 begins to saturate, the saturation detector 45 uses a first controllable bias current source 46 to control the peak amplifier 42. Additionally, if the saturation of the carrier amplifier 41 is deeper, the saturation detector 45 uses a second controllable bias current source 47 to control the load modulation amplifier 43. Thus, in this embodiment, the saturation detector 45 is used to set a first power threshold for activating the peak amplifier 42 and a second power threshold for activating the load modulation amplifier 43.

[0049] Figure 6 is a schematic diagram of a load-modulated Doherty power amplifier 140 of another embodiment. The load-modulated Doherty power amplifier 140 includes a carrier amplifier 101, a peak amplifier 102, a load modulation amplifier 103, a 3dB hybrid coupler 104, and an input splitter 105.

[0050] In the illustrated embodiment, the input splitter 105 includes a first 3dB hybrid coupler 107, a second 3dB hybrid coupler 108, a first termination resistor 109, and a second termination resistor 110. The COM port of the first 3dB hybrid coupler 107 is connected to the RF input section RF INWhile the first 3dB hybrid coupler 107 is coupled to the first 3dB hybrid coupler 107, its ISO port is connected to the first termination resistor 109 (which may be connected to ground in a given implementation). Additionally, the 90° port of the first 3dB hybrid coupler 107 outputs the input signal component LM for the load modulation amplifier 103, while the 0° port of the first 3dB hybrid coupler 107 is connected to the COM port of the second 3dB hybrid coupler 108. Additionally, the ISO port of the second 3dB hybrid coupler 108 is connected to the second termination resistor 110 (which may be connected to ground in a given implementation), while the 90° port of the second 3dB hybrid coupler 108 outputs the input signal component CR for the carrier amplifier 101, and the 0° port of the second 3dB hybrid coupler 108 outputs the input signal component PK for the peak amplifier 102.

[0051] The carrier amplifier 101 includes a carrier amplification stage 111 (e.g., a common-emitter amplifier stage or another suitable stage), a Class AB bias circuit 113, a bias resistor 114, and a saturation detector 115. The carrier amplifier 101 includes an input section that receives the input signal component CR and an output section that is coupled to the 0° port of a 3dB hybrid coupler 104. The Class AB bias circuit 113 biases the carrier amplification stage 111, while the saturation detector 115 detects the saturation level of the carrier amplification stage 111.

[0052] Continuing to refer to Figure 6, the peak amplifier 102 includes a common-emitter amplifier stage 121, a Class AB bias circuit 123, a bias resistor 124, and a controllable current source 125 controlled by a saturation detector 115 of the carrier amplifier 101. The peak amplifier 102 includes an input section that receives the input signal component PK and an output section that is coupled to the 90° port of a 3dB hybrid coupler 104.

[0053] The load modulation amplifier 103 includes a cascode amplifier stage implemented using a gain transistor 131 and a cascode transistor 132. The load modulation amplifier 103 further includes a class AB bias circuit 133, a bias resistor 134, and a controllable current source 135 controlled by a saturation detector 115 of the carrier amplifier 101. The load modulation amplifier 103 includes an input section that receives the input signal component LM and an output section that is coupled to the ISO port of a 3dB hybrid coupler 104.

[0054] In the illustrated embodiment, the 3dB hybrid coupler 104 further comprises an RF output section RF OUT This includes a COM port to which the load modulation amplifier 103 is connected. In this embodiment, since the 3dB hybrid coupler 104 has a characteristic impedance X, the output impedance of the load modulation amplifier 103 is approximately -jX. In one example, X is approximately 35 ohms.

[0055] Figure 7 is a graph showing an example of gain versus output power for a load-modulated Doherty power amplifier. The graph includes gain versus output power plots for different bias current conditions for one implementation example of the load-modulated Doherty power amplifier 140 shown in Figure 6.

[0056] Figure 8 is a graph showing an example of power added efficiency (PAE) versus output power for a load-modulated Doherty power amplifier. The graph includes PAE versus output power plots for a single implementation example of the load-modulated Doherty power amplifier 140 from Figure 6, under different bias current conditions.

[0057] Figure 9 is a graph of another example of PAE versus output power for a load-modulated Doherty power amplifier. The graph shows the PAE performance of one implementation example of the load-modulated Doherty power amplifier 140 shown in Figure 6. In this example, 70% of the PAE is achieved with a 5dB power backoff (PBO).

[0058] Although Figures 7-9 illustrate an example of the performance results of a load-modulated Doherty power amplifier, other performance results are also possible. For example, the performance results of a load-modulated Doherty power amplifier may depend on various factors, including but not limited to the amplifier's implementation, operating conditions, frequency range, and / or simulation / measurement environment.

[0059] Figure 10 is a schematic diagram of a portable device 800 according to one embodiment. The portable 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.

[0060] 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 NR, WLAN (e.g., WiFi), WPAN (e.g., Bluetooth® and ZigBee®), WMAN (e.g., WiMAX), and / or GPS technology.

[0061] The transceiver 802 generates an RF signal for transmission and processes the incoming RF signal received from the antenna 804. It is understood that the various functions associated with transmitting and receiving RF signals can be achieved by one or more components, collectively represented as the transceiver 802 in Figure 10. In one example, a separate component (e.g., a separate circuit or die) may be provided to handle a predetermined type of RF signal.

[0062] The front-end system 803 assists in conditioning the signals transmitted to and / or received from antenna 804. In the illustrated embodiment, the front-end system 803 includes an antenna tuning circuit 810, a plurality of power amplifiers (PAs) 801, a plurality of low-noise amplifiers (LNAs) 812, a plurality of filters 813, a plurality of switches 814, and a signal splitting / coupling circuit 815. However, other implementations are possible.

[0063] For example, the front-end system 803 can provide a certain number of functions, including, but not limited to, amplification of the transmit signal, amplification of the receive signal, filtering of the signal, switching between different bands, switching between different power modes, switching between the transmit mode and the receive mode, duplexing of the signal, multiplexing of the signal (e.g., diplexing or triplexing), or any combination thereof.

[0064] At least one of the multiple power amplifiers 811 is implemented as a load-modulated Doherty power amplifier as taught herein. Although the portable device 800 demonstrates one embodiment of a communication system in which one or more load-modulated Doherty power amplifiers may be implemented, the teaching herein is applicable to a wide range of systems. Therefore, other implementation examples are also possible.

[0065] In a given implementation example, the portable device 800 supports carrier aggregation, providing flexibility to increase the peak data rate. Carrier aggregation can be used with both frequency-division duplexing (FDD) and time-division duplexing (TDD), and may be used to aggregate multiple carriers or channels. Carrier aggregation includes adjacent aggregation, where continuous carriers are aggregated within the same operating frequency band. Carrier aggregation may be discontinuous and may include carriers whose frequencies are separated within a common band or different bands.

[0066] The multiple antennas 804 may include antennas used for a wide variety of types of communication. For example, antennas 804 may include antennas for transmitting and / or receiving signals associated with a wide variety of frequencies and communication standards.

[0067] In a given implementation example, antenna 804 supports MIMO communication and / or switched diversity communication. For example, MIMO communication uses multiple antennas to communicate multiplexed data streams over a single radio frequency channel. MIMO communication benefits from a high signal-to-noise ratio, improved coding, and / or reduced signal interference due to the spatial multiplexing of the radio environment. Switched diversity refers to communication in which a specific antenna is selected to operate at a particular time. For example, a switch can be used to select a specific antenna from a group of antennas based on various factors such as the observed bit error rate and / or signal strength index.

[0068] The portable device 800 may operate with beamforming in a given implementation. For example, the front-end system 803 may include an amplifier with controllable gain and a phase shifter with controllable phase to provide beamforming and directivity for transmitting and / or receiving signals using antenna 804. For example, in the context of signal transmission, the amplitude and phase of the transmit signal supplied to antenna 804 are controlled so that the signal radiated from antenna 804 is coupled using constructive and destructive interference, resulting in an aggregated transmit signal exhibiting beam-like quality with strong signal intensity propagating in a given direction. In the context of signal reception, the amplitude and phase are controlled so that more signal energy is received when the signal arrives at antenna 804 from a particular direction. In a given implementation, antenna 804 includes one or more arrays of antenna elements to enhance beamforming.

[0069] The baseband system 801 is coupled to a user interface 807 that facilitates the processing of various user input / output (I / O), such as voice and data processing. The baseband system 801 provides a digital representation of the transmit signal to the transceiver 802, which processes this to generate an RF signal for transmission. The baseband system 801 also processes the digital representation of the receive signal provided by the transceiver 802. As shown in Figure 10, the baseband system 801 is coupled to a memory 806 to facilitate the operation of the portable device 800.

[0070] Memory 806 can be used for a wide variety of purposes, such as storing data and / or instructions, in order to facilitate the operation of the portable device 800 and / or to provide storage for user information.

[0071] The power management system 805 provides a certain number of power management functions for the portable device 800. In a given implementation example, the power management system 805 includes a PA supply control circuit that controls the supply voltage of a plurality of power amplifiers 811. For example, the power management system 805 may be configured to change the supply voltage supplied to one or more of the plurality of power amplifiers 811 in order to improve an efficiency such as power added efficiency (PAE).

[0072] As shown in Figure 10, the power management system 805 receives the battery voltage from the battery 808. The battery 808 may be any suitable battery for use in the portable device 800, including, for example, a lithium-ion battery.

[0073] Figure 11 is a schematic diagram of a power amplifier system 860 according to another embodiment. The illustrated power amplifier system 860 includes a baseband processor 841, a transmitter / observation receiver 842, a power amplifier (PA) 843, a directional coupler 844, a front-end circuit 845, an antenna 846, a PA bias control circuit 847, and a PA supply control circuit 848. The illustrated transmitter / observation receiver 842 includes an I / Q modulator 857, a mixer 858, and an analog-to-digital converter (ADC) 859. In a given implementation example, the transmitter / observation receiver 842 is incorporated into a transceiver.

[0074] The baseband processor 841 may be used to generate in-phase (I) and quadrature (Q) signals that can be used to represent a sine wave or sine 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 a sine wave, thereby providing an equivalent representation of the sine wave. In a given implementation example, the I and Q signals are provided to the I / Q modulator 857 in digital form. The baseband processor 841 may be any suitable processor configured to process baseband signals. For example, the baseband processor 841 may include a digital signal processor, a microprocessor, a programmable core, or any combination thereof. Furthermore, in some implementation examples, two or more baseband processors 821 may be included in the power amplifier system 860.

[0075] The I / Q modulator 857 is configured to receive I and Q signals from the baseband processor 821 and process the I and Q signals to generate an RF signal. For example, the I / Q modulator 857 may include multiple digital-to-analog converters (DACs) that convert the I and Q signals into analog format, a mixer that upconverts the I and Q signals to RF, and a signal coupler that combines the upconverted I and Q signals to produce an RF signal suitable for amplification by the power amplifier 843. In a given implementation example, the I / Q modulator 857 may include one or more filters configured to filter the frequency components of the signal being processed.

[0076] The power amplifier 843 receives an RF signal from the I / Q modulator 857 and, when activated, can provide the amplified RF signal to the antenna 846 via the front-end circuit 845. The power amplifier 843 can be implemented according to any of the load modulation schemes described here.

[0077] The front-end circuit 845 can be implemented in a wide variety of ways. In one example, the front-end circuit 845 includes one or more switches, filters, duplexers, multiplexers, and / or other components. In another example, the front-end circuit 845 is omitted, and the power amplifier 843 directly supplies the amplified RF signal to the antenna 846.

[0078] The directional coupler 844 senses the output signal of the power amplifier 823. Additionally, the sensed output signal is fed from the directional coupler 844 to the mixer 858, which multiplies the sensed output signal by a control frequency reference signal. The mixer 858 operates to generate a downshifted signal by downshifting the frequency components of the sensed output signal. The downshifted signal may be fed to the ADC 859, which can convert the downshifted signal into a digital format suitable for processing by the baseband processor 841. The feedback path from the output of the power amplifier 843 to the baseband processor 841 can provide several advantages. For example, implementing the baseband processor 841 in this manner can assist in providing power control, compensating for transmitter failures, and / or performing digital predistortion (DPD). Although one example of a sense path for the power amplifier is shown, other implementations are possible.

[0079] The PA supply control circuit 848 receives a power control signal from the baseband processor 841 and controls the supply voltage of the power amplifier 843. In the illustrated configuration, the PA supply control circuit 848 supplies a first supply voltage V to the input stage of the power amplifier 843. CC1and a second supply voltage V for supplying power to the output stage of the power amplifier 843 CC2 and are generated. The PA supply control circuit 848 is configured to improve the PAE of the power amplifier system by changing the voltage levels of the first supply voltage V CC1 and / or the second supply voltage V CC2 . The voltage levels of can be controlled.

[0080] The PA supply control circuit 848 can use various power management techniques to reduce power dissipation by changing the voltage levels of one or more of these supply voltages over time to improve the power added efficiency (PAE) of the power amplifier.

[0081] One technique for improving the efficiency of a power amplifier is average power tracking (APT). In this case, a DC / DC converter is used to generate a supply voltage for the power amplifier based on the average output power of the power amplifier. 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 to be related to the envelope of the RF signal. That is, when the voltage level of the envelope of the RF signal increases, the voltage level of the supply voltage of the power amplifier can increase. Similarly, when 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.

[0082] In a given configuration, the PA supply control circuit 848 is a multi-mode supply control circuit that can operate in a number of supply control modes, including APT mode and ET mode. For example, a power control signal from the baseband processor 841 can command the PA supply control circuit 848 to operate in a specific supply control mode.

[0083] As shown in FIG. 11, the PA bias control circuit 847 receives a bias control signal from the baseband processor 841 and generates a bias control signal for the power amplifier 843. In the illustrated configuration, the bias control circuit 847 generates bias control signals for both the input stage and the output stage of the power amplifier 843. However, other implementations are possible.

[0084] Figure 12A is a schematic diagram of a package module 900 according to one embodiment. Figure 12B is a schematic diagram of a cross-section of the package module 900 along the line 12B-12B in Figure 12A.

[0085] The package module 900 includes a radio frequency component 901, a semiconductor die 902, a surface mount device 903, a wire bond 908, a package substrate 920, and an encapsulation structure 940. The package substrate 920 includes a pad 906 formed from a conductor placed inside. Additionally, the semiconductor die 902 includes pins or pads 904, and the wire bond 908 is used to connect the pad 904 of the die 902 to the pad 906 of the package substrate 920.

[0086] The semiconductor die 902 includes a load-modulated Doherty power amplifier 945, which may be implemented according to any of the embodiments herein. In this embodiment, a saturation detector 946 may also be included to control the activation of the peak amplifier and the load-modulated amplifier. However, other implementations of bias / activation control are also possible.

[0087] The packaging substrate 920 is configured to accept multiple components, such as a radio frequency component 901 including a surface-mount capacitor and / or inductor, a semiconductor die 902, and a surface-mount device 903. In one packaging example, the radio frequency component 901 includes an integrated passive device (IPD).

[0088] As shown in Figure 12B, the package module 900 includes a plurality of contact pads 932. The plurality of contact pads 932 are located on the opposite side of the package module 900 from the side used to mount the semiconductor die 902. Configuring the package module 900 in this manner can assist in connecting the package module 900 to a circuit board, such as a telephone board for a mobile device. Examples of contact pads 932 can be configured to supply radio frequency signals, bias signals, and / or power (e.g., power supply voltage and ground) to the semiconductor die 902 and / or other components. As shown in Figure 12B, the electrical connection between the contact pads 932 and the semiconductor die 902 can be facilitated by a connection portion 933 via the package substrate 920. The connection portion 933 may represent an electrical path formed through the package substrate 920, such as a connection portion associated with vias and conductors of a multilayer package substrate.

[0089] In some embodiments, the package module 900 may also include one or more package structures that provide, for example, protection and / or facilitate handling. Such package structures may include an overmolding or encapsulation structure 940 formed on the package substrate 920 on which the components and dies are placed.

[0090] It should be understood that, although the package module 900 is described in the context of wire-bonded electrical connections, one or more features of this disclosure can also be implemented in other package configurations, such as a flip-chip configuration.

[0091] summary

[0092] Unless the context explicitly requires otherwise, throughout the specification and claims, terms such as “includes,” “equip,” and so on should be interpreted in a comprehensive sense, the opposite of an exclusive or exhaustive sense, i.e., “includes but not limited to.” The term “combined,” as used herein, refers to two or more elements that may be directly connected or connected via one or more intermediate elements. Similarly, the term “connected,” as used herein, refers to two or more elements that may be directly connected or connected via one or more intermediate elements. In addition, where used in this application, the terms “here,” “above,” “below,” and similar terms refer to the entire application and not to any particular part of it. Where contextually permissible, terms in the above detailed description that use singular or plural numbers may also include plural or singular numbers. The terms “or” and “or” referring to a list of two or more items cover all of the following interpretations of the term: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0093] Furthermore, unless specifically stated or understood otherwise in the context in which they are used, conditional language used herein, in particular, such as “may,” “can,” “perhaps,” “for example,” and “like,” is generally intended to mean that a given embodiment includes a given feature, element, and / or state, while other embodiments do not. That is, such conditional language is generally not intended to imply that the feature, element, and / or state exists in any manner required for one or more embodiments, or that one or more embodiments necessarily include logic that determines, with or without the author’s input or prompt, whether or not these feature, element, and / or state are included, or should be done in any particular embodiment.

[0094] The above description of embodiments of the present invention is not intended to be exhaustive or to limit the invention to any specific form of the above disclosure. While specific embodiments and examples of the present invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as will be apparent to those skilled in the art. For example, while processes or blocks are presented in a given order, alternative embodiments may employ systems having routines or 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 various different ways. Furthermore, while processes or blocks may be shown to be executed in series, these processes or blocks may instead be executed in parallel or at different times.

[0095] The teachings of the present invention given herein can be applied to other systems, not necessarily those described above. The elements and operations of the various embodiments described above may be combined to provide further embodiments.

[0096] While certain embodiments of the present invention have been described, these embodiments are presented only as examples and are not intended to limit the scope of this disclosure. In fact, the novel methods and systems described herein may be embodied in various other forms, and various omissions, substitutions, and modifications of the methods and systems described herein may be made without departing from the spirit of this disclosure. The appended claims and their equivalents are intended to cover forms or modifications that fall within the scope and spirit of this disclosure.

Claims

1. A power amplifier system, A coupler including a first terminal, a second terminal, a third terminal and a fourth terminal, A carrier amplifier including an output section coupled to the first terminal of the coupler, A peak amplifier including an output section coupled to the second terminal of the coupler, A load modulation amplifier including an output section coupled to the third terminal of the coupler Includes, The coupler is configured to provide a radio frequency output signal from the fourth terminal, The peak amplifier is configured to become active at the first power threshold, The load modulation amplifier is configured to become active at a second power threshold greater than the first power threshold. A power amplifier system in which, when the load modulation amplifier is activated, it is capable of operating to modulate the loads of the carrier amplifier and the peak amplifier to a low impedance.

2. The carrier amplifier includes a saturation detector configured to monitor the saturation level of the carrier amplifier. The power amplifier system according to claim 1, wherein the saturation detector is operable to control the activation of the peak amplifier and to control the activation of the load modulation amplifier.

3. The carrier amplifier includes a Class AB bias circuit. The peak amplifier includes a first Class C bias circuit. The power amplifier system according to claim 1, wherein the load modulation amplifier includes a second Class C bias circuit.

4. The power amplifier system according to claim 1, wherein the load modulation amplifier includes a cascode amplifier stage.

5. The carrier amplifier includes a first common emitter amplifier stage, The power amplifier system according to claim 4, wherein the peak amplifier includes a second common-emitter amplifier stage.

6. The aforementioned coupler is a hybrid coupler, The first terminal corresponds to a zero-degree port, The second terminal corresponds to a 90-degree port, The third terminal corresponds to an isolation port, The power amplifier system according to claim 1, wherein the fourth terminal corresponds to a common port.

7. The power amplifier system according to claim 1, further comprising an input divider configured to divide a radio frequency input signal into a plurality of input signal components, including a first input signal component supplied to the input of the carrier amplifier and a second input signal component supplied to the input of the peak amplifier.

8. The power amplifier system according to claim 7, wherein the plurality of input signal components further include a third input signal component supplied to the input section of the load modulation amplifier.

9. It is a mobile device, An antenna configured to transmit a radio frequency output signal, Front-end system including power amplifier system and Includes, The power amplifier system includes a coupler, a carrier amplifier having an output section coupled to a first terminal of the coupler, a peak amplifier having an output section coupled to a second terminal of the coupler, and a load modulation amplifier having an output section coupled to a third terminal of the coupler. The coupler is configured to provide a radio frequency output signal at the fourth terminal, The peak amplifier is configured to become active at the first power threshold, The load modulation amplifier is configured to become active at a second power threshold greater than the first power threshold. A portable device in which, when the load modulation amplifier is activated, it becomes capable of modulating the loads of the carrier amplifier and the peak amplifier to a low impedance.

10. The carrier amplifier includes a saturation detector configured to monitor the saturation level of the carrier amplifier. The portable device according to claim 9, wherein the saturation detector is operable to control the activation of the peak amplifier and to control the activation of the load modulation amplifier.

11. The carrier amplifier includes a Class AB bias circuit. The peak amplifier includes a first Class C bias circuit. The portable device according to claim 9, wherein the load modulation amplifier includes a second Class C bias circuit.

12. The portable device according to claim 9, wherein the load modulation amplifier includes a cascode amplifier stage.

13. The aforementioned coupler is a hybrid coupler, The first terminal corresponds to a zero-degree port, The second terminal corresponds to a 90-degree port, The third terminal corresponds to an isolation port, The portable device according to claim 9, wherein the fourth terminal corresponds to a common port.

14. A method of amplification in a mobile phone, The first radio frequency signal is supplied from the output of the carrier amplifier to the first terminal of the coupler, The second radio frequency signal is supplied from the output section of the peak amplifier to the second terminal of the coupler, The third radio frequency signal is supplied from the output section of the load modulation amplifier to the third terminal of the coupler, The first radio frequency signal, the second radio frequency signal, and the third radio frequency signal are combined using the aforementioned coupler to generate a radio frequency output signal. The fourth terminal of the coupler is used to provide the radio frequency output signal, Activating the peak amplifier at the first power threshold, Activating the load modulation amplifier at a second power threshold greater than the first power threshold, Includes, A method for activating the load modulation amplifier, comprising modulating the loads of the carrier amplifier and the peak amplifier to a low impedance.

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