Doherty power amplifier, power amplifier control method, packaged device

Abstract

This application relates to the field of power amplifier technology, and discloses a Doherty power amplifier, a power amplifier control method, and a packaged device. The power amplifier includes a signal injection circuit, a carrier power amplifier branch, a peak power amplifier branch, and a power detection circuit. The carrier power amplifier branch includes a carrier power amplifier, and the peak power amplifier branch includes a peak power amplifier. The output terminal of the signal injection circuit is connected to the input terminals of both the carrier power amplifier branch and the peak power amplifier branch. The power detection circuit is disposed between the input terminals of the carrier power amplifier and the peak power amplifier. When the carrier power amplifier is in a first operating state, the power detection circuit outputs a first base voltage to the peak power amplifier to turn it off; and when the carrier power amplifier is in a second operating state, it outputs a second base voltage to the peak power amplifier to turn it on. The technical solution provided by this application can improve the output efficiency and linearity of the power amplifier within the power back-off range.

Description

Technical Field

[0001] This application relates to the field of power amplifier technology, and in particular to Doherty power amplifiers, power amplifier control methods, and packaging devices. Background Technology

[0002] Since the load impedance of traditional power amplifiers is usually fixed, their efficiency will decrease in the power back-off state. Therefore, the Doherty power amplifier was developed to address this issue by dynamically adjusting the output load impedance, thereby enabling the power amplifier to maintain high output efficiency over a wide power range.

[0003] In practical applications, traditional Doherty power amplifiers include a carrier power amplifier and a peak power amplifier. They typically employ a peak power amplifier turn-on mechanism based on Class C bias and driven by the input power, using a preset turn-on threshold. However, due to the characteristics of the transistors themselves, bias circuitry, or improper preset turn-on threshold settings, the peak power amplifier exhibits a certain turn-on electrical delay. This causes the current in the peak power amplifier to not be injected in a timely manner, thus affecting the output efficiency and linearity of the Doherty power amplifier in the power back-off range.

[0004] Therefore, how to further improve the output efficiency and linearity of Doherty power amplifiers in the power back-off range has become a key research focus in the field of power amplifier technology. Summary of the Invention

[0005] This application provides a Doherty power amplifier, a power amplifier control method, and a packaged device, which can improve the output efficiency and linearity of the Doherty power amplifier in the power back-off range.

[0006] This application provides a Doherty power amplifier, comprising: a signal injection circuit, a carrier power amplifier branch, a peak power amplifier branch, and a power detection circuit. The carrier power amplifier branch includes a carrier power amplifier, and the peak power amplifier branch includes a peak power amplifier. The output terminal of the signal injection circuit is connected to the input terminal of the carrier power amplifier branch and the input terminal of the peak power amplifier branch, respectively. The power detection circuit is disposed between the input terminal of the carrier power amplifier and the input terminal of the peak power amplifier. The power detection circuit is used to output a first base voltage to the peak power amplifier when the carrier power amplifier is in a first operating state, thereby turning off the peak power amplifier; and to output a second base voltage to the peak power amplifier when the carrier power amplifier is in a second operating state, thereby turning on the peak power amplifier. The first base voltage is lower than the second base voltage. The first and second operating states are used to characterize different saturation states of the carrier power amplifier.

[0007] In one embodiment, the power detection circuit includes a third transistor; wherein: if the carrier power amplifier is in a first operating state, the third transistor is turned on based on the base voltage of the carrier power amplifier in the first operating state to output a first base voltage to the peak power amplifier; if the carrier power amplifier is in a second operating state, the third transistor is turned off based on the base voltage of the carrier power amplifier in the second operating state to output a second base voltage to the peak power amplifier.

[0008] In one embodiment, the first operating state and the second operating state are determined based on the base voltage change of the carrier power amplifier; wherein: when the base voltage change indicates that the base voltage of the carrier power amplifier remains unchanged within a first preset range, the carrier power amplifier is determined to be in the first operating state; when the base voltage change indicates that the base voltage of the carrier power amplifier drops to a second preset range, the carrier power amplifier is determined to be in the second operating state.

[0009] In one embodiment, the power detection circuit further includes a fifth resistor, a third capacitor, and a sixth resistor; wherein: the input terminal of the carrier power amplifier is connected to the base of the third transistor through the fifth resistor, the input terminal of the peak power amplifier is connected to the collector of the third transistor through the sixth resistor, one end of the third capacitor is connected to the base of the third transistor, the other end of the third capacitor is connected to the emitter of the third transistor, and the emitter of the third transistor is grounded.

[0010] In one embodiment, the carrier power amplifier branch includes a carrier power amplifier driver, a first-stage inter-matching network, a carrier bias circuit, and a carrier power amplifier connected in series. The peak power amplifier branch includes a peak power amplifier driver, a second-stage inter-matching network, a peak bias circuit, and a peak power amplifier connected in series. The carrier bias circuit is used to control the carrier power amplifier to be biased in Class AB mode and to provide a first bias voltage to the carrier power amplifier, the first bias voltage being used to determine the base voltage of the carrier power amplifier. The peak bias circuit is used to control the peak power amplifier to be biased in Class AB mode and to provide a second bias voltage to the peak power amplifier, the second bias voltage being used to determine the base voltage of the peak power amplifier.

[0011] In one embodiment, the carrier bias circuit includes a first resistor, a third resistor, a first transistor, a first diode, a second diode, and a first capacitor; the peak bias circuit includes a second resistor, a fourth resistor, a second transistor, a third diode, a fourth diode, and a second capacitor; wherein the cathode of the second diode is grounded, the third resistor is a ballast resistor, the cathode of the fourth diode is grounded, and the fourth resistor is a ballast resistor.

[0012] In one embodiment, the power amplifier further includes a load impedance matching network, and the carrier power amplifier branch further includes an impedance transformation network. The input terminal of the impedance transformation network is connected to the output terminal of the carrier power amplifier, and the output terminal of the impedance transformation network is connected to the input terminal of the load impedance matching network.

[0013] In one embodiment, the signal input circuit includes an input matching network, a first-stage driver, and a power divider connected in series; wherein: the power divider is used to distribute the signal output by the first-stage driver to the carrier power amplifier branch and the peak power amplifier branch, and introduces a 90° phase delay when the signal is distributed to the peak power amplifier branch.

[0014] A second aspect of this application provides a power amplifier control method for a power amplifier, the method being applied to the Doherty power amplifier described in the first aspect above. The method includes: detecting the operating state of a carrier power amplifier in real time through a power detection circuit, wherein the operating state is used to characterize the saturation of the carrier power amplifier; if the detection result indicates that the carrier power amplifier is in a first operating state, controlling the peak power amplifier to turn off through the power detection circuit to control the power amplifier to operate in a first power mode; if the detection result indicates that the carrier power amplifier is in a second operating state, controlling the peak power amplifier to turn on through the power detection circuit to control the power amplifier to operate in a second power mode.

[0015] A third aspect of this application provides a packaged device including the Doherty power amplifier as described in the first aspect above.

[0016] The technical solution provided in one or more embodiments of this application improves the output efficiency and linearity of a Doherty power amplifier by precisely turning on the peak power amplifier based on the operating state of the carrier power amplifier through a power detection circuit. Specifically, the power detection circuit can monitor different saturation states of the carrier power amplifier in real time, and output a first base voltage below the conduction threshold to the peak power amplifier to turn it off when the carrier power amplifier is in a first operating state that is not close to saturation, and output a second base voltage to the peak power amplifier to turn it on quickly when the carrier power amplifier is in a second operating state that is close to saturation. Compared with traditional Doherty power amplifiers, this technical solution can accurately and timely turn on the peak power amplifier when the carrier power amplifier is close to saturation by directly detecting the operating state of the carrier power amplifier and precisely controlling the base voltage of the peak power amplifier. This avoids efficiency dips and nonlinear distortions caused by turn-on delay, too early or too late turn-on time, and significantly improves the output efficiency and linearity of the Doherty power amplifier in the power back-off range.

[0017] As can be seen, the technical solution provided in this application can accurately and timely activate the peak power amplifier when the carrier power amplifier is close to saturation, thereby improving the output efficiency and linearity of the Doherty power amplifier in the power back-off range. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a conventional Doherty power amplifier provided in one embodiment of this application; Figure 2 A schematic diagram of the structure of a Doherty power amplifier provided for one embodiment of this application; Figure 3 A circuit diagram of a power detection circuit provided in one embodiment of this application; Figure 4 A circuit diagram of a Doherty power amplifier provided for one embodiment of this application; Figure 5 A schematic diagram illustrating the steps of a power amplifier control method provided in one embodiment of this application; Figure 6 This is a schematic diagram illustrating the steps of a method for detecting the operating state of a carrier power amplifier, provided as one embodiment of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] With the increasing demands for data transmission efficiency in modern high-speed wireless communication technology, signal modulation methods are evolving towards systems with high peak-to-average power ratio (PAPR). PAPR signals place higher demands on the linearity of power amplifiers, requiring them to operate in a large power back-off state—that is, within a power back-off range where the actual operating power is significantly lower than the amplifier's saturation power. This power back-off range can be understood as the range of the amplifier's actual output power relative to its saturation power, typically including a portion of the low-power region, a transition region, and a portion of the high-power region. Generally, traditional power amplifiers have a fixed load impedance, and their output efficiency drops significantly within the power back-off range. Introducing Doherty power amplifiers based on load dynamic modulation can address these issues to some extent.

[0022] Please see Figure 1 This application provides a scenario example of a conventional Doherty power amplifier. A conventional Doherty power amplifier includes a carrier power amplifier and a peak power amplifier connected in parallel, as well as an input signal power divider, a quarter-wavelength transmission line (i.e., an impedance transformation network), and a load matching network. The carrier power amplifier operates with Class AB bias, and the peak power amplifier operates with Class C bias. The input RF signal first enters the power divider, where it is split into two: one path goes directly to the carrier power amplifier, and the other path, after a -90° phase delay, goes to the peak power amplifier. The carrier power amplifier is directly connected to the quarter-wavelength transmission line, and the 90° phase delay allows it to be added in phase with the output signal of the peak power amplifier.

[0023] Specifically, when the input power is low, the Doherty power amplifier is in low-power mode, meaning the peak power amplifier is off and only the carrier power amplifier is working. In this mode, the load impedance at the output is 2R. As the input power increases, when the carrier power amplifier approaches saturation and the signal amplitude is sufficient to drive the Class C peak power amplifier, the peak power amplifier turns on, and the power amplifier enters high-power mode. In this mode, both amplifiers work together, and their output power is superimposed. At this point, the load impedance of the carrier power amplifier decreases from 2R to R, while the load impedance of the peak power amplifier decreases from infinity to R. Ideally, the maximum output power in high-power mode can be approximately 6dB higher than that in low-power mode. Therefore, by dynamically adjusting the load impedance, high output efficiency of the power amplifier can be achieved, making it particularly suitable for processing signals with a high peak-to-average power ratio (PAPR).

[0024] However, due to the inherent characteristics of transistors (such as charge storage effects) and the influence of bias circuits, the peak power amplifier exhibits a certain turn-on electrical delay, leading to a decrease in the output efficiency of the Doherty power amplifier in the power back-off range. Ideally, the peak power amplifier should turn on smoothly and instantly when the carrier power amplifier reaches its saturation point (efficiency peak). However, due to the electrical delay in the peak power amplifier's turn-on, current cannot be injected into the peak power amplifier on time, forcing the carrier power amplifier to operate in a low-efficiency state in the transition region, resulting in a lower average efficiency of the Doherty power amplifier in the power back-off range. Simultaneously, the peak power amplifier's turn-on delay also causes a decrease in the linearity of the Doherty power amplifier in the power back-off range. Because of the electrical delay in the peak power amplifier's turn-on, if the input power has increased but the peak power amplifier has not yet turned on, all the load is borne by the carrier power amplifier alone, forcing the carrier power amplifier to enter deep saturation prematurely, resulting in severe gain compression and signal distortion, such as AM-AM distortion and AM-PM distortion. That is, the changes in output amplitude (AM-AM) and phase (AM-PM) relative to the input power will produce significant nonlinear distortion.

[0025] Furthermore, in Doherty power amplifiers, turning on the peak amplifier too early or too late will disrupt its high-efficiency operating characteristics. Specifically, traditional Doherty power amplifiers typically turn on the peak amplifier based on a preset turn-on threshold of the input power. If the preset turn-on threshold is set improperly, causing the peak amplifier to turn on too early, it will divert some current, preventing the carrier amplifier from being fully driven to saturation, thus reducing the output efficiency of the Doherty power amplifier in the transition region. Moreover, turning on the peak amplifier too early will disrupt load modulation. That is, when the peak amplifier is off, the carrier amplifier should see a higher load impedance to achieve high efficiency, but turning it on too early will prematurely lower this impedance, thereby reducing the output efficiency of the Doherty power amplifier in the power back-off range.

[0026] The above description is merely a scenario example provided in the specification and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0027] In view of the above, one or more embodiments of this application provide a Doherty power amplifier, a power amplifier control method, and a packaged device, which can solve the above problems. By directly monitoring the operating status of the carrier power amplifier, the peak power amplifier can be turned on accurately and timely when the carrier power amplifier is close to saturation, thereby improving the output efficiency and linearity of the Doherty power amplifier in the power back-off range.

[0028] Please see Figure 2One embodiment of this application provides a Doherty power amplifier, including: a signal injection circuit, a carrier power amplifier branch, a peak power amplifier branch, and a power detection circuit. The carrier power amplifier branch includes a carrier power amplifier CA, and the peak power amplifier branch includes a peak power amplifier PA, wherein: The output terminal of the above signal injection circuit is connected to the input terminal of the above carrier power amplifier branch and the input terminal of the above peak power amplifier branch, respectively. The above power detection circuit is located between the input terminal of the above carrier power amplifier CA and the input terminal of the above peak power amplifier PA. The power detection circuit described above is used to output a first base voltage to the peak power amplifier PA when the carrier power amplifier CA is in a first operating state, so as to turn off the peak power amplifier PA, and to output a second base voltage to the peak power amplifier PA when the carrier power amplifier CA is in a second operating state, so as to turn on the peak power amplifier PA. The first base voltage is lower than the second base voltage. The first operating state and the second operating state are used to characterize different saturation conditions of the carrier power amplifier CA.

[0029] In this embodiment, the signal injection circuit is used to split the input current and input it separately to the carrier power amplifier branch and the peak power amplifier branch. Typically, the signal injection circuit includes an input matching network, a first-stage driver, and a power divider connected in sequence. The input matching network is used to achieve impedance matching between the input signal and the first-stage driver. The first-stage driver is used to initially amplify the input signal, and the power divider is used to split the initially amplified input signal into two parts, which are then sent to the carrier power amplifier branch and the peak power amplifier branch, respectively. Traditional Doherty power amplifiers require monitoring the input power on the signal injection circuit and determining whether to activate the peak power amplifier (PA) based on a preset turn-on threshold. However, due to the influence of subsequent circuit design and the transistor characteristics of the carrier power amplifier (CA), the peak power amplifier (PA) is prone to turn-on delay, resulting in an efficiency dip in the power back-off range.

[0030] In this embodiment, the carrier power amplifier branch includes a carrier power amplifier CA, the input of which is connected to a signal injection circuit to receive one signal obtained by the signal injection circuit splitting the signal. The peak power amplifier branch includes a peak power amplifier PA, the input of which is connected to the signal injection circuit to receive the other signal obtained by the splitting. The outputs of the carrier power amplifier CA and the peak power amplifier PA are connected through a combining point so that the two signals from the carrier power amplifier branch and the peak power amplifier branch can be added in phase at the combining point. The carrier power amplifier CA and the peak power amplifier PA act as power amplifier transistors. The carrier power amplifier CA can operate normally at any input power level, while the peak power amplifier PA is only turned on at higher power levels (i.e., when the carrier power amplifier is close to saturation) and works in conjunction with the carrier power amplifier CA, thereby maintaining high efficiency over a wide power range. It should be noted that in low power levels (when the carrier power amplifier CA is not yet close to saturation), the signal will still be input to the input of the peak power amplifier PA, but since the peak power amplifier PA is in a turned-off state, no signal amplification will occur.

[0031] In this embodiment, the operating state of the carrier power amplifier (CA) is detected to determine whether the peak power amplifier (PA) needs to be turned on. The operating state of the carrier power amplifier (CA) includes a first operating state and a second operating state. The first operating state indicates that the carrier power amplifier (CA) is not close to saturation, i.e., the power amplifier is in a low-power state and has not yet reached the turn-on timing of the peak power amplifier (PA). The second operating state indicates that the carrier power amplifier (CA) is close to saturation, i.e., the power amplifier is in a high-power state and has reached the turn-on timing of the peak power amplifier (PA). Further, the turn-on or turn-off operation of the peak power amplifier (PA) is based on the base voltage of the peak power amplifier (PA). When the base voltage of the peak power amplifier (PA) is the first base voltage, the peak power amplifier (PA) is turned off, i.e., the peak power amplifier (PA) is in a completely off state. The first base voltage is typically 0V. When the base voltage is the second base voltage, the peak power amplifier (PA) is turned on. The second base voltage is preferably the conduction bias voltage of the peak power amplifier (PA).

[0032] In this embodiment, the power detection circuit outputs the base voltage required by the peak power amplifier PA. Specifically, the power detection circuit can output a first base voltage or a second base voltage to the peak power amplifier PA according to the operating state of the carrier power amplifier CA, thereby turning the peak power amplifier off or on accordingly. That is, when the carrier power amplifier CA is in the first operating state, the first base voltage is output to the peak power amplifier PA to turn it off, and when the carrier power amplifier CA is in the second operating state, the second base voltage is output to the peak power amplifier PA to turn it on. Compared with the threshold judgment mechanism based on input power in the traditional technology, judging based on the operating state of the carrier power amplifier CA can more accurately and timely determine the timing of the peak power amplifier PA's turn-on. Furthermore, by directly adjusting the base voltage of the peak power amplifier PA through the power detection circuit, the second base voltage can be directly applied to the peak power amplifier PA, thereby enabling the peak power amplifier PA to enter the turn-on state more quickly. This allows for precise and timely turn-on of the peak power amplifier PA when the carrier power amplifier CA is close to saturation, thereby improving the output efficiency and linearity of the Doherty power amplifier in the power back-off range.

[0033] Based on the above ideas, the technical solution provided in this embodiment of the application improves the output efficiency and linearity of the Doherty power amplifier by accurately turning on the peak power amplifier based on the operating state of the carrier power amplifier through a power detection circuit. Specifically, the power detection circuit can monitor different saturation states of the carrier power amplifier in real time, and output a first base voltage below the conduction threshold to the peak power amplifier to turn it off when the carrier power amplifier is in a first operating state that is not close to saturation, and output a second base voltage to the peak power amplifier to turn it on quickly when the carrier power amplifier is in a second operating state that is close to saturation. Compared with the traditional Doherty power amplifier, this technical solution can accurately and timely turn on the peak power amplifier when the carrier power amplifier is close to saturation by directly detecting the operating state of the carrier power amplifier itself and accurately controlling the base voltage of the peak power amplifier. This avoids efficiency dips and nonlinear distortions caused by turn-on delay, too early or too late turn-on time, and significantly improves the output efficiency and linearity of the Doherty power amplifier in the power back-off range.

[0034] In one embodiment, the power detection circuit includes a third transistor. The power detection circuit outputs the base voltage required by the peak power amplifier, i.e., a first base voltage or a second base voltage, which is determined based on the on / off state of the third transistor. Specifically, by turning the third transistor on or off, the base voltage of the peak power amplifier is modulated to the first base voltage or the second base voltage, thereby turning the peak power amplifier off or on. If the carrier power amplifier is in a first operating state, the third transistor is turned on based on the base voltage of the carrier power amplifier in the first operating state to output the first base voltage to the peak power amplifier; if the carrier power amplifier is in a second operating state, the third transistor is turned off based on the base voltage of the carrier power amplifier in the second operating state to output the second base voltage to the peak power amplifier.

[0035] Specifically, the base of the third transistor is connected to the input terminal of the carrier power amplifier, the collector of the third transistor is connected to the input terminal of the carrier power amplifier, and the emitter of the third transistor is grounded. When the carrier power amplifier is in its first operating state, the base voltage of the carrier power amplifier is high, causing the third transistor to conduct. Since the collector of the third transistor is grounded, it outputs a first base voltage to the peak power amplifier, which approaches zero voltage, and the peak power amplifier is turned off. As the carrier power amplifier approaches saturation, the transistor current increases. Due to the self-heating effect of the transistors inside the carrier power amplifier and the rectification effect of the diodes, the base voltage of the carrier power amplifier will decrease. When the carrier power amplifier is in its second operating state, the base voltage of the carrier power amplifier will drop below the transistor turn-on threshold of the third transistor, causing the third transistor to turn off and its collector to open to ground. This allows the base voltage of the peak power amplifier to recover to the second base voltage, i.e., the normal bias voltage, and the peak power amplifier turns on.

[0036] The technical solution provided in this embodiment refines the adjustment mechanism of the peak power amplifier's voltage across multiple waves in the power detection circuit. By incorporating a third transistor in the power detection circuit, the switching on and off of the third transistor is determined by the base voltage state of the carrier power amplifier. This enables precise sensing of the carrier power amplifier's saturation state and direct control of the peak power amplifier's base voltage, thereby allowing for timely and accurate activation of the peak power amplifier. This avoids efficiency dips and nonlinear distortion caused by turn-on delays, premature or late turn-on times, and significantly improves the output efficiency and linearity of the Doherty power amplifier within the power back-off range.

[0037] In one specific implementation, please refer to Figure 3The aforementioned power detection circuit includes a third transistor Q3, a fifth resistor R5, a third capacitor C3, and a sixth resistor R6. Specifically, the input terminal of the carrier power amplifier CA is connected to the base of the third transistor Q3 via the fifth resistor R5; the input terminal of the peak power amplifier PA is connected to the collector of the third transistor Q3 via the sixth resistor R6; one end of the third capacitor C3 is connected to the base of the third transistor Q3, and the other end of the third capacitor C3 is connected to the emitter of the third transistor Q3. The emitter of the third transistor Q3 is grounded. Specifically, adding the fifth resistor R5 between the input terminal of the carrier power amplifier CA and the third transistor Q3 prevents damage due to excessive base current in the third transistor Q3; adding the sixth resistor R6 between the input terminal of the peak power amplifier PA and the third transistor Q3 prevents the base of the peak power amplifier PA from short-circuiting to ground through the collector of the third transistor Q3 when the third transistor Q3 is conducting; the third capacitor C3 is used to improve the stability of the power detection circuit's grounding.

[0038] The technical solution provided in this embodiment constructs a power detection circuit consisting of a third transistor, a fifth resistor, a sixth resistor, and a third capacitor. It achieves real-time sensing of the carrier power amplifier's operating state and precise control of the peak power amplifier's base voltage through a simplified resistor-capacitor-inductor structure and a single transistor, reducing circuit complexity and cost. Furthermore, by directly triggering the peak power amplifier's activation based on changes in the carrier power amplifier's own state, it ensures that the peak power amplifier can quickly and promptly intervene when the carrier power amplifier approaches saturation. This avoids efficiency dips and nonlinear distortion caused by activation delays, premature or late activation, and improves the output efficiency and linearity of the Doherty power amplifier in the power back-off range.

[0039] In one embodiment, the first operating state and the second operating state are determined based on the base voltage change of the carrier power amplifier. Specifically: when the base voltage change indicates that the base voltage of the carrier power amplifier is within a first preset range and remains constant, the carrier power amplifier is determined to be in the first operating state, and the current carrier power amplifier outputs a first base voltage to the peak power amplifier via the power detection circuit, and the peak power amplifier should be turned off; when the base voltage change indicates that the base voltage of the carrier power amplifier drops to a second preset range, the carrier power amplifier is determined to be in the second operating state, and the current carrier power amplifier outputs a second base voltage to the peak power amplifier via the power detection circuit, and the peak power amplifier should be turned on.

[0040] The aforementioned first preset range refers to a base voltage greater than or equal to a first preset threshold, such as greater than or equal to 1.2V. This first preset threshold is typically set as the standard bias voltage of the carrier power amplifier, determined based on the process conditions of the power amplifier transistors. Because the junction temperature of the carrier power amplifier is stable and its self-heating effect is not significant under low power conditions, its base voltage usually remains at a relatively high stable value. Specifically, the base voltage change characterizes the base voltage of the carrier power amplifier within the first preset range and remains constant. This can be understood as the base voltage of the carrier power amplifier being a certain voltage value within the first preset range and remaining constant at that voltage value, for example, the base voltage of the carrier power amplifier remaining constant at 1.2V.

[0041] The aforementioned second preset range refers to a base voltage less than or equal to a second preset threshold, for example, less than or equal to 1.15V. As output power increases, the surge in current leads to a self-heating effect, causing the base voltage of the carrier power amplifier to decrease with a negative temperature coefficient. When the base voltage drops to the second preset range, it indicates that the carrier power amplifier is nearing saturation and the peak power amplifier needs to be activated. Specifically, the base voltage change characterizes the carrier power amplifier's base voltage dropping to the second preset range, which can be understood as the carrier power amplifier's base voltage dropping to the second preset threshold within the second preset range. It should be noted that the aforementioned second preset range is lower than the aforementioned first preset range, and the aforementioned second preset threshold is lower than the aforementioned first preset threshold. The aforementioned second preset threshold is typically set as the base voltage value at which the carrier power amplifier just enters the pre-saturation state, and its value is determined based on the transistor's manufacturing process conditions.

[0042] The technical solution provided in this embodiment concretizes the first and second operating states of the carrier power amplifier into quantitative determinations based on changes in its base voltage. Specifically, by setting a clear voltage threshold range, the saturation level of the carrier power amplifier is transformed into a quantifiable operating state. This allows the power detection circuit to accurately and quickly activate the peak power amplifier based on the base voltage of the carrier power amplifier and its changing trend. This ensures that the peak power amplifier is accurately triggered the instant the carrier power amplifier enters the pre-saturation state, thereby avoiding efficiency dips and nonlinear distortion caused by activation delays, premature or late activation, and improving the output efficiency and linearity of the Doherty power amplifier in the power back-off range.

[0043] In one embodiment, the carrier power amplifier branch includes a carrier power amplifier driver, a first-stage inter-matching network, a carrier bias circuit, and a carrier power amplifier connected in series. The peak power amplifier branch includes a peak power amplifier driver, a second-stage inter-matching network, a peak bias circuit, and a peak power amplifier connected in series. The carrier power amplifier driver amplifies the signal received by the carrier power amplifier branch, bringing the signal to the input power range of the carrier power amplifier. The first-stage inter-matching network performs impedance conversion between the carrier power amplifier driver and the carrier power amplifier. The peak power amplifier driver amplifies the signal received by the peak power amplifier branch, bringing the signal to the input power range of the peak power amplifier. The second-stage inter-matching network performs impedance conversion between the peak power amplifier driver and the peak power amplifier.

[0044] In this embodiment, the carrier bias circuit is used to control the carrier power amplifier to be biased in Class AB mode and to provide a first bias voltage to the carrier power amplifier, the first bias voltage being used to determine the base voltage of the carrier power amplifier; the peak bias circuit is used to control the peak power amplifier to be biased in Class AB mode and to provide a second bias voltage to the peak power amplifier, the second bias voltage being used to determine the base voltage of the peak power amplifier. Specifically, the first bias voltage is applied to the base of the carrier power amplifier, and the base voltage of the carrier power amplifier is determined based on the first bias voltage and internal disturbances, such as self-heating effects and rectification effects. The second bias voltage is applied to the base of the peak power amplifier, and the second base voltage of the peak power amplifier is determined based on the second bias voltage and internal disturbances. The first base voltage of the peak power amplifier is typically zero voltage due to the influence of the power detection circuit.

[0045] In traditional Doherty power amplifiers, the aforementioned carrier power amplifier is typically biased in Class AB mode, while the aforementioned peak power amplifier is typically biased in Class C mode. This allows the peak power amplifier to achieve Class C turn-off, i.e., turning on or off based on a preset turn-on threshold. Because the power amplifier transistor biased in Class AB mode has a longer conduction time and better linearity, while the power amplifier transistor biased in Class C mode is in the off state for most of the time, exhibiting drastic nonlinear characteristics when turned on. Therefore, the transition of the peak power amplifier from the cutoff region to conduction is a highly nonlinear process, with its transconductance changing drastically near the preset turn-on threshold. This results in significant nonlinear distortion when the peak power amplifier is turned on, such as AM-AM distortion and AM-PM distortion.

[0046] In this embodiment, the peak power amplifier is also biased into Class AB mode. By simulating Class C shutdown through a power detection circuit to achieve the high back-off efficiency of the Doherty power amplifier, the severe nonlinear distortion problem that occurs when the traditional Doherty power amplifier is turned on can be avoided. Specifically, when the transistor in the power detection circuit is turned off, since the peak power amplifier is biased into Class AB, its base voltage can smoothly recover from the low voltage state to the normal bias voltage, achieving a linear transition rather than abrupt turn-on. This avoids the severe nonlinear transition region from the cutoff region to the amplification region of the traditional Class C power amplifier. Furthermore, by accurately and timely controlling the turn-on time of the peak power amplifier through the power detection circuit, the linearity of the Doherty power amplifier can be further improved.

[0047] In this embodiment, the carrier bias circuit includes a first resistor, a third resistor, a first transistor, a first diode, a second diode, and a first capacitor. The peak bias circuit includes a second resistor, a fourth resistor, a second transistor, a third diode, a fourth diode, and a second capacitor. The cathode of the second diode is grounded, the third resistor is a ballast resistor, and the cathode of the fourth diode is grounded, with the fourth resistor also serving as a ballast resistor. The ballast resistor is used to stabilize the bias current and prevent bias point drift caused by temperature changes or excessive RF signals. For example, when the base current of the carrier power amplifier changes, the voltage drop across the third resistor changes accordingly, forming a negative feedback mechanism to suppress drastic fluctuations in the bias current.

[0048] In this embodiment, the Doherty power amplifier further includes a load impedance matching network, and the carrier power amplifier branch further includes an impedance transformation network. The input terminal of the impedance transformation network is connected to the output terminal of the carrier power amplifier, and the output terminal of the impedance transformation network is connected to the input terminal of the load impedance matching network. The impedance transformation network is a passive network used to determine the impedance seen by the carrier power amplifier based on the state changes of the peak power amplifier, enabling the carrier power amplifier to maintain high efficiency over a wide power range. The load impedance matching network is used to transform a fixed system load to the specific impedance required for the Doherty combining point. It should be noted that the impedance of the impedance transformation network can be dynamically matched with power changes, and the load impedance matching network only performs impedance matching at the combining point once.

[0049] In this embodiment, dynamic load modulation of the Doherty power amplifier can be achieved through an impedance transformation network and a load impedance matching network. For example, the system load is... For example, an antenna, typically 50 ohms, undergoes impedance matching via a load impedance matching network to generate the specific impedance required at the synthesis point. Furthermore, an impedance transformation network is used to amplify or reduce the change in the synthesized impedance and present it to the carrier power amplifier to achieve dynamic load control. The impedance seen by the carrier power amplifier will change from the low power state. Gradually changing to high power The impedance seen by the peak power amplifier gradually changes from infinity at low power to... By dynamically adjusting the output load impedance, the power amplifier can maintain high efficiency over a wide power range.

[0050] The technical solution provided in this embodiment details the specific composition and operating mode of the carrier power amplifier branch, the peak power amplifier branch, the carrier bias circuit, and the peak bias circuit. Specifically, the carrier power amplifier and the peak power amplifier are biased in Class AB operating mode. A load impedance matching network transforms the fixed system load to the specific impedance required for the synthesis point. Furthermore, dynamic load modulation is achieved through an impedance transformation network, ensuring that the carrier power amplifier and the peak power amplifier exhibit adaptive impedances when power changes, achieving high-efficiency output over a wide power range. Compared to traditional technologies where the peak power amplifier is biased in Class C, this technical solution, by biasing the peak power amplifier in Class AB mode, avoids the AM-AM and AM-PM nonlinear distortions caused by the drastic transconductance changes during the transition from the cutoff region to the amplification region in Class C power amplifiers. Furthermore, a power detection circuit that operates according to the operating state of the carrier power amplifier is introduced, thereby accurately and timely controlling the turn-on time of the peak power amplifier, further improving the linearity of the Doherty power amplifier.

[0051] In one embodiment, the signal input circuit includes an input matching network, a first-stage driver, and a power divider connected in series; wherein: the power divider is used to distribute the signal output by the first-stage driver to the carrier power amplifier branch and the peak power amplifier branch, the input matching network is used to achieve impedance matching between the input signal and the first-stage driver, and the first-stage driver is used to perform preliminary amplification of the input signal.

[0052] In this embodiment, when the carrier power amplifier branch also includes an impedance transformation network, the power divider is further used to introduce a 90° phase delay when the signal is distributed to the peak power amplifier branch. The impedance transformation network typically uses a quarter-wavelength transmission line, which introduces a 90-degree phase delay at the end of the carrier power amplifier branch. To achieve effective power superposition rather than mutual cancellation, the two output signals must remain in phase at the combining point. Therefore, to ensure phase consistency between the peak power amplifier branch and the carrier power amplifier branch signals at the combining point, a 90-degree phase delay is pre-introduced to the peak power amplifier through a signal injection circuit, so that the two signals accumulate the same total delay during transmission, allowing them to be added in phase at the combining point.

[0053] The technical solution provided in this embodiment can ensure effective power combining of the two amplified signals, improving the output efficiency and reliability of the power amplifier. Specifically, when an impedance transformation network is provided in the carrier power amplifier branch, the power divider actively introduces a 90° phase delay when distributing the signal to the peak power amplifier branch to pre-compensate for the 90° phase delay introduced by the impedance transformation network in the carrier power amplifier branch. This ensures that the two signals accumulate the same total delay during transmission, ultimately achieving precise in-phase addition at the combining point, thereby improving the output reliability of the Doherty power amplifier. Please refer to Figure 4 This application provides an embodiment of a Doherty power amplifier. In this embodiment, the Doherty power amplifier includes a signal injection circuit, a carrier power amplifier branch, a peak power amplifier branch, a power detection circuit, a load impedance matching network (LMN), and a system load. The signal injection circuit includes an input matching network, a first-stage driver, and a power divider PS. The carrier power amplifier branch includes a carrier power amplifier driver CA_Driver, a first-stage inter-stage matching network IMN1, a carrier bias circuit, a carrier power amplifier CA, and an impedance transformation network IM. The peak power amplifier branch includes a peak power amplifier driver PA_Driver, an inter-stage matching network IMN2, a peak bias circuit, and a peak power amplifier PA.

[0054] The power detection circuit includes a third transistor Q3, a fifth resistor R5, a third capacitor C3, and a sixth resistor R6. The input terminal of the carrier power amplifier CA is connected to the base of the third transistor Q3 through the fifth resistor R5. The input terminal of the peak power amplifier PA is connected to the collector of the third transistor Q3 through the sixth resistor R6. One end of the third capacitor C3 is connected to the base of the third transistor Q3, and the other end of the third capacitor C3 is connected to the emitter of the third transistor Q3. The emitter of the third transistor Q3 is grounded (GND). The carrier bias circuit includes a first resistor R1, a third resistor R3, a first transistor Q1, a first diode D1, a second diode D2, and a first capacitor C1. The peak bias circuit includes a second resistor R2, a fourth resistor R4, a second transistor Q2, a third diode D3, a fourth diode D4, and a second capacitor C2. The cathodes of the second diode D2 and the fourth diode D4 are grounded (GND).

[0055] In this embodiment, when the input power is low, the output power of the carrier power amplifier CA is also low. The base voltage of the carrier power amplifier CA is high and remains unchanged. It is transmitted to the base of the third transistor Q3 through the fifth resistor R5, causing the third transistor Q3 to conduct. The base voltage of the peak power amplifier PA is transmitted to the collector of the third transistor Q3 through the sixth resistor R6. The third transistor Q3 is in the conducting state at this time. The collector is connected to ground through the emitter. Therefore, the base voltage of the peak power amplifier PA is in a low voltage state. At this time, the peak power amplifier PA is in the off state.

[0056] In this embodiment, as the carrier power amplifier CA approaches saturation, the transistor current of the carrier power amplifier CA increases. Due to the self-heating effect of the transistor and the rectification effect of the diode, the base voltage of the carrier power amplifier CA will decrease. The base voltage of the third transistor Q3, which is transmitted to the power detection circuit through the fifth resistor R5, also decreases, causing the third transistor Q3 to be in the off state. At this time, the base voltage of the peak power amplifier PA is connected to ground, and the path is broken. The base voltage of the peak power amplifier PA recovers from low voltage to normal voltage, and the peak power amplifier PA is in the working state. Finally, the entire Doherty power amplifier enters the high power mode.

[0057] Secondly, please refer to Figure 5 This application also provides a power amplifier control method for a power amplifier, the method being applied to the Doherty power amplifier described in the first aspect above, the method being performed according to the following steps: S1: The operating status of the carrier power amplifier is detected in real time through the power detection circuit, wherein the operating status is used to characterize the saturation of the carrier power amplifier; S3: If the detection result indicates that the carrier power amplifier is in the first working state, the peak power amplifier is turned off through the power detection circuit to control the power amplifier to work in the first power mode. S5: If the detection result indicates that the carrier power amplifier is in the second working state, the peak power amplifier is turned on through the power detection circuit to control the power amplifier to work in the second power mode.

[0058] In one implementation, please refer to Figure 6 The above operating state is determined based on the base voltage change of the carrier power amplifier; the operating state of the carrier power amplifier is detected in real time by the power detection circuit and the following steps are performed: S11: The base voltage of the carrier power amplifier is detected in real time through the power detection circuit, so as to determine the base voltage change based on the detection results; S13: When the base voltage change indicates that the base voltage of the carrier power amplifier remains unchanged within a first preset range, it is determined that the carrier power amplifier is in the first working state. S15: When the base voltage change indicates that the base voltage of the carrier power amplifier drops to the second preset range, it is determined that the carrier power amplifier is in the second working state.

[0059] The system utilizes a power detection circuit to monitor the base voltage of the carrier power amplifier in real time. This can be understood as using the carrier power amplifier's base voltage as a real-time status signal reflecting its saturation level. The power detection circuit continuously captures this base voltage to determine whether the peak power amplifier needs to be activated, thereby regulating its base voltage for precise and rapid activation. Specifically, the power detection circuit responds to the base voltage of the carrier power amplifier connected to its base via its built-in third transistor. If the carrier power amplifier's base voltage is sufficient to turn on the third transistor, and since the peak power amplifier is connected to the collector of the third transistor (which is grounded), its base voltage is zero. If the carrier power amplifier's base voltage drops below the level required to turn on the third transistor, the peak power amplifier's base voltage returns to normal, and the peak power amplifier is activated.

[0060] The further functional descriptions of each of the above steps are the same as those in the corresponding embodiments of the first aspect described above, and will not be repeated here.

[0061] Thirdly, this application also provides a packaged device, the packaged device including the Doherty power amplifier described in the first aspect above.

[0062] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a method or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to the method or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the method or apparatus that includes said element.

[0063] Furthermore, an element is considered to be "connected" to another element; this can be a direct connection to another element or the presence of an intervening element. Additionally, descriptions using terms such as "first," "second," etc., in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Furthermore, the use of "based on" or "according to" implies openness and inclusivity, as processes, steps, calculations, or other actions "based on" or "according to" one or more of the stated conditions or values ​​may in practice be based on additional conditions or beyond the stated values.

[0064] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments; relevant parts can be referred to in the descriptions of other embodiments. The multiple embodiments provided in this application are used to illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

[0065] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0066] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A Doherty power amplifier, characterized by, include: The circuit includes a signal injection circuit, a carrier power amplifier branch, a peak power amplifier branch, and a power detection circuit. The carrier power amplifier branch includes a carrier power amplifier, and the peak power amplifier branch includes a peak power amplifier. The output terminal of the signal injection circuit is connected to the input terminal of the carrier power amplifier branch and the input terminal of the peak power amplifier branch, respectively, and the power detection circuit is disposed between the input terminal of the carrier power amplifier and the input terminal of the peak power amplifier. The power detection circuit is used to output a first base voltage to the peak power amplifier when the carrier power amplifier is in a first operating state, so as to turn off the peak power amplifier, and to output a second base voltage to the peak power amplifier when the carrier power amplifier is in a second operating state, so as to turn on the peak power amplifier. The first base voltage is lower than the second base voltage. The first operating state and the second operating state are used to characterize different saturation conditions of the carrier power amplifier.

2. The Doherty power amplifier according to claim 1, characterized in that, The power detection circuit includes a third transistor; wherein: If the carrier power amplifier is in the first operating state, the third transistor is turned on based on the base voltage of the carrier power amplifier in the first operating state to output the first base voltage to the peak power amplifier. If the carrier power amplifier is in the second operating state, the third transistor is turned off based on the base voltage of the carrier power amplifier in the second operating state, so as to output the second base voltage to the peak power amplifier.

3. The Doherty power amplifier according to claim 1 or 2, characterized in that, The first operating state and the second operating state are determined based on the base voltage variation of the carrier power amplifier; wherein: When the base voltage change indicates that the base voltage of the carrier power amplifier remains unchanged within a first preset range, the carrier power amplifier is determined to be in a first operating state. When the base voltage change indicates that the base voltage of the carrier power amplifier has dropped to a second preset range, the carrier power amplifier is determined to be in a second operating state.

4. The Doherty power amplifier according to claim 2, characterized in that, The power detection circuit further includes a fifth resistor, a third capacitor, and a sixth resistor; wherein: The input terminal of the carrier power amplifier is connected to the base of the third transistor through the fifth resistor, the input terminal of the peak power amplifier is connected to the collector of the third transistor through the sixth resistor, one end of the third capacitor is connected to the base of the third transistor, the other end of the third capacitor is connected to the emitter of the third transistor, and the emitter of the third transistor is grounded.

5. The Doherty power amplifier according to claim 1, characterized in that, The carrier power amplifier branch includes a carrier power amplifier driver, a first-stage inter-matching network, a carrier bias circuit, and a carrier power amplifier connected in series. The peak power amplifier branch includes a peak power amplifier driver, a second-stage inter-matching network, a peak bias circuit, and a peak power amplifier connected in series. The carrier bias circuit is used to control the carrier power amplifier to be biased in Class AB mode and to provide a first bias voltage to the carrier power amplifier, wherein the first bias voltage is used to determine the base voltage of the carrier power amplifier. The peak bias circuit is used to control the peak power amplifier to be biased in Class AB mode and to provide a second bias voltage for the peak power amplifier, the second bias voltage being used to determine the base voltage of the peak power amplifier.

6. The Doherty power amplifier according to claim 5, characterized in that, The carrier bias circuit includes a first resistor, a third resistor, a first transistor, a first diode, a second diode, and a first capacitor; the peak bias circuit includes a second resistor, a fourth resistor, a second transistor, a third diode, a fourth diode, and a second capacitor. The cathode of the second diode is grounded, the third resistor is a ballast resistor, the cathode of the fourth diode is grounded, and the fourth resistor is a ballast resistor.

7. The Doherty power amplifier according to claim 5, characterized in that, The power amplifier further includes a load impedance matching network, and the carrier power amplifier branch further includes an impedance transformation network. The input terminal of the impedance transformation network is connected to the output terminal of the carrier power amplifier, and the output terminal of the impedance transformation network is connected to the input terminal of the load impedance matching network.

8. A power amplifier control method for a power amplifier, characterized in that, The method is applied to the Doherty power amplifier as described in any one of claims 1 to 7, and the method includes: The operating status of the carrier power amplifier is detected in real time by a power detection circuit, wherein the operating status is used to characterize the saturation of the carrier power amplifier. If the detection result indicates that the carrier power amplifier is in the first working state, the peak power amplifier is turned off through the power detection circuit to control the power amplifier to work in the first power mode. If the detection result indicates that the carrier power amplifier is in the second working state, the peak power amplifier is turned on through the power detection circuit to control the power amplifier to work in the second power mode.

9. The method according to claim 8, characterized in that, The operating state is determined based on the base voltage change of the carrier power amplifier; the real-time detection of the operating state of the carrier power amplifier by the power detection circuit includes: The power detection circuit detects the base voltage of the carrier power amplifier in real time, and determines the base voltage change based on the detection results. When the base voltage change indicates that the base voltage of the carrier power amplifier remains unchanged within a first preset range, the carrier power amplifier is determined to be in a first operating state. When the base voltage change indicates that the base voltage of the carrier power amplifier has dropped to a second preset range, the carrier power amplifier is determined to be in a second operating state.

10. A packaged device, characterized in that, Includes the Doherty power amplifier as described in any one of claims 1 to 7.

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