Active dynamic bias circuit of Doherty power amplifier, Doherty power amplifier circuit and module

Abstract

The present application provides a Doherty power amplifier circuit and module with an active dynamic bias circuit for a Doherty power amplifier. The active dynamic bias circuit includes: a first control voltage; a bias switching circuit including a voltage divider circuit connected to the first control voltage, the voltage divider circuit including a switch element and a voltage divider element connected in series; a second control voltage connected to the control end of the switch element; the switch element is controlled by the first control voltage, the second control voltage, and the RF input power; the voltage divider circuit includes a voltage divider output end connected to the gate of an auxiliary power amplifier; when the input power is greater than a preset value, the switch element closes, forming a path for the voltage divider circuit, and the voltage divider circuit provides a gate bias to the auxiliary power amplifier, so that the auxiliary power amplifier operates in Class AB. In this way, the auxiliary power amplifier operates in Class AB within the high-power input signal range, combining the advantages of Class A and Class B power amplifiers to effectively improve the power and gain of the overall circuit.

Description

Technical Field

[0001] The present application relates to the technical field of power amplifiers, and in particular to an active dynamic bias circuit of a Doherty power amplifier, a Doherty power amplifier circuit, and a Doherty power amplifier module. Background Art

[0002] The signals in modern communication systems have a high peak-to-average ratio. At the same time, the power consumption requirements of the product hardware system are becoming increasingly stringent. Therefore, the application of high back-off efficiency power amplifiers, such as Doherty power amplifiers, is becoming more and more widespread.

[0003] Traditional Doherty power amplifiers have high back-off efficiency and can meet the current communication field's demand for high peak-to-average ratio signals. However, this amplifier structure also has its own disadvantages. Since the Doherty power amplifier requires a power divider at the input to distribute power, this leads to a decrease in the linear gain of the Doherty power amplifier, thereby worsening efficiency. After the auxiliary power amplifier is turned on, since the auxiliary power amplifier usually operates in Class C and has a low gain, the gain of the entire Doherty power amplifier circuit is further reduced, which also has a certain negative impact on the linearity of the circuit. Summary of the Invention

[0004] To solve the existing technical problems, the present application provides an active dynamic bias circuit of a Doherty power amplifier that can effectively improve the power and gain of the power amplifier, a Doherty power amplifier circuit including the active dynamic bias circuit, and a Doherty power amplifier module including the Doherty power amplifier circuit.

[0005] In a first aspect, an active dynamic bias circuit for a Doherty power amplifier is provided, comprising:

[0006] a first control voltage;

[0007] a bias switching circuit comprising a voltage dividing circuit connected to the first control voltage, the voltage dividing circuit comprising a switching element and a voltage dividing element connected in series;

[0008] a second control voltage connected to the control terminal of the switch element;

[0009] The switching element is controlled by the first control voltage, the second control voltage and the RF input power. The voltage divider circuit includes a voltage divider output terminal connected to the gate of the auxiliary power amplifier of the Doherty power amplifier. When the RF input power is greater than a preset value, the switching element is closed to form a path for the voltage divider circuit. The voltage divider circuit provides a gate bias to the auxiliary power amplifier so that the auxiliary power amplifier operates in class AB.

[0010] In a second aspect, a Doherty power amplifier circuit is provided, comprising a main power amplifier, an auxiliary power amplifier, and the active dynamic bias circuit described in any embodiment of the present application;

[0011] The active dynamic bias circuit is connected to the input side of the main power amplifier.

[0012] In a third aspect, a Doherty power amplifier module is provided, comprising a chip and a packaging substrate, wherein the chip or the packaging substrate is provided with the Doherty power amplifier circuit described in any embodiment of the present application.

[0013] The active dynamic bias circuit provided in the above embodiment, through the setting of the bias switching circuit, uses the first control voltage to provide a voltage divider for the voltage divider circuit in the path state, and uses the second control circuit to provide a control voltage for the voltage divider circuit to form a path. The switching element in the voltage divider circuit is controlled by the first control voltage, the second control voltage and the RF input power. When the RF input power is greater than the preset value, the gate bias is provided to the auxiliary power amplifier through the voltage divider circuit that forms the path, so that the auxiliary power amplifier operates in Class AB. In this way, the auxiliary power amplifier can provide additional power gain by overlapping the working state with the main power amplifier within the high-power input signal range. The auxiliary power amplifier operates in Class AB, which can combine the advantages of Class A and Class B power amplifiers, reduce power loss, and improve signal integrity, thereby effectively improving the power and gain of the overall circuit of the power amplifier.

[0014] The Doherty power amplifier circuit and Doherty power amplifier module provided in the above embodiments have the same concept as the corresponding active dynamic bias circuit embodiments, and thus have the same technical effects as the corresponding active dynamic bias circuit embodiments, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. 4 is a block diagram of an active dynamic bias circuit of a Doherty power amplifier according to an embodiment.

[0016] Figure 2 FIG. 1 is a schematic diagram of the circuit structure of an active dynamic bias circuit of a Doherty power amplifier in one embodiment.

[0017] Figure 3 FIG. 1 is a schematic diagram of the circuit structure of a Doherty power amplifier circuit in one embodiment.

[0018] Figure 4 FIG. 4 is a structural diagram of a Doherty power amplifier module in one embodiment.

[0019] Component Symbol Description:

[0020] Active dynamic bias circuit 10, power divider 12, bias switching circuit 13, switch element 131, voltage divider 132, control terminal 133, first voltage divider branch 134, second voltage divider branch 135, switch circuit 136, main power amplifier 14, auxiliary power amplifier 15, chip 21, and package substrate 22;

[0021] First control voltage Vctrl1, second control voltage Vctrl2, first transistor D1, second transistor D2, first voltage divider resistor R1, second voltage divider resistor R2, equalizing resistor R4, first rectifier diode Do1, second rectifier diode Do2, control switch tube SW1, DC blocking capacitor C1, first filter capacitor C2, second filter capacitor C3. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] In order to make the purpose, technical solutions and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limiting this application. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0024] In the following description, the expression "some embodiments" is involved, which describes a subset of all possible embodiments. It should be noted that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0025] It should also be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "inner", "outer", "left", "right" and similar expressions used herein are only for illustrative purposes in conjunction with the embodiments of the accompanying drawings and do not represent the only implementation methods.

[0026] Please refer to Figure 1 and Figure 2An embodiment of the present application provides an active dynamic bias circuit 10 for a Doherty power amplifier, comprising: a first control voltage Vctrl1, a bias switching circuit 13, and a second control voltage Vctrl2. The bias switching circuit 13 includes a voltage divider circuit connected to the first control voltage Vctrl1, and the voltage divider circuit includes a switch element 131 and a voltage divider element 132 connected in series. The second control voltage Vctrl2 is connected to the control end of the switch element 131. The switch element 131 is controlled by the first control voltage Vctrl1, the second control voltage Vctrl2, and the RF input power. The voltage divider circuit includes a voltage divider output end connected to the gate of an auxiliary power amplifier of the Doherty power amplifier. When the RF input power is greater than a preset value, the switch element 131 is closed, thereby forming a path for the voltage divider circuit. The voltage divider circuit provides a gate bias to the auxiliary power amplifier 15, so that the auxiliary power amplifier 15 operates in class AB.

[0027] The first control voltage Vctrl1 and the second control voltage Vctrl2 can be independent external power sources. The voltage divider circuit is connected to the first control voltage Vctrl1. When the voltage divider circuit is in operation, the first control voltage Vctrl1 provides a voltage divider. The second control voltage Vctrl2 is connected to the control terminal of the switch element 131, providing a control voltage to the voltage divider circuit for controlling the operating state of the switch element 131. The active dynamic bias circuit is connected to the input side of the main power amplifier of the Doherty power amplifier. In this way, the switch element 131 is simultaneously controlled by the first control voltage Vctrl1, the second control voltage Vctrl2, and the RF input power at the input side of the main power amplifier. The voltage divider circuit includes a voltage divider output terminal connected to the gate of the auxiliary power amplifier of the Doherty power amplifier. By setting the first control voltage Vctrl1 and the second control voltage Vctrl2, when the RF input power exceeds a preset value, the switch element 131 is controlled to close, thereby completing the operation of the voltage divider circuit.

[0028] In the above embodiment, the active dynamic bias circuit 10 uses the first control voltage Vctrl1 to provide a voltage divider voltage source for the voltage divider circuit in the on state through the setting of the bias switching circuit 13, and uses the second control voltage Vctrl2 to provide a control voltage for controlling the working state of the switch element 131 in the voltage divider circuit. The switch element 131 in the voltage divider circuit is controlled by the first control voltage Vctrl1, the second control voltage Vctrl2 and the RF input power. The voltage divider circuit includes a voltage divider output terminal connected to the gate of the auxiliary power amplifier 15 of the Doherty power amplifier. In this way, combined with the working characteristics of the switch element 131 and the use of the second control voltage Vctrl2, the voltage divider circuit 131 is connected to the gate of the auxiliary power amplifier 15 of the Doherty power amplifier. A control voltage Vctrl1 and a second control voltage Vctrl2 are set. When the RF input power is greater than a preset value, a gate bias can be provided to the auxiliary power amplifier 15 through a voltage divider circuit that forms a path, so that the auxiliary power amplifier 15 operates in Class AB. In this way, the auxiliary power amplifier 15 can provide additional power gain within the high-power input signal range by overlapping the working state with the main power amplifier 14. By making the auxiliary power amplifier 15 operate in Class AB, the advantages of Class A and Class B power amplifiers can be combined to reduce power loss and improve signal integrity, thereby effectively improving the power and gain of the overall circuit of the power amplifier.

[0029] Power amplifiers operate in different modes: Class A, Class B, Class AB, and Class C. In Class A, all transistors remain on when there's no input signal, and the output amplifies the full signal wave without crossover distortion, resulting in ideal amplification linearity. However, the downside is that full current still flows even when there's no signal, converting electrical energy into heat and causing significant power loss. In Class B, the transistors are off when there's no input signal. When there's a signal, each pair of output transistors amplifies half the signal, alternating between on and off to complete full-wave amplification. However, crossover distortion and nonlinearity occur when the output transistors are switched. In Class AB, a small amount of current flows through the output transistors even when there's no signal. When the signal is weak, it operates in Class A mode for optimal linearity. When the signal reaches a certain level, it automatically switches to Class B mode for higher efficiency. Class C converts the input signal into a pulse-width modulated (PWM) signal, which is then amplified by the transistors. The downside is higher distortion.

[0030] In some embodiments, the bias switching circuit 13 further includes a switching circuit 136, which includes a control switch SW1 connected between the two outputs of the power divider 12; the voltage divider circuit includes a first voltage divider branch 134 and a second voltage divider branch 135 connected in parallel, wherein the first voltage divider branch 134 provides a switch control voltage to the control switch SW1, and the second voltage divider branch 135 provides a gate bias voltage to the auxiliary power amplifier 15. The first voltage divider branch 134 and the second voltage divider branch 135 are connected in parallel. In a specific example, the control switch SW1 is a depletion-type (normally open) device, typically a depletion-type field-effect transistor, such as a gallium nitride high electron mobility transistor. When the first voltage divider branch 134 is in an off-circuit state, the switch control voltage provided by the first voltage divider branch 134 to the control switch SW1 is 0V. At this time, the control switch SW1 is turned on, the two outputs of the power divider 12 are short-circuited, and the two ports of the power divider 12 are merged, thereby eliminating a certain amount of insertion loss of the power divider 12. The insertion loss of the power divider 12 refers to the loss generated when the signal passes through the power divider 12, usually expressed in decibels (dB). This loss is due to the fact that when the signal is transmitted inside the power divider 12 and distributed to multiple output ports, part of the signal energy is converted into heat energy or other forms of energy loss, resulting in a weakening of the output signal strength. Taking a two-output power divider as an example, under ideal conditions, the power output of any one output is half of the input function, which is understood logarithmically as 10*lg2=3dB less than the original. The merging of the two output ports can reduce the loss corresponding to one output port, that is, the 3dB insertion loss of the power divider 12 can be removed. When the second voltage divider branch 135 is in the open circuit state, the gate bias voltage provided by the second voltage divider branch 135 to the auxiliary power amplifier 15 is close to the first control voltage Vctrl1. By setting the size of the first control voltage Vctrl1, the auxiliary power amplifier 15 operates in Class C and will not affect the matching state of the main power amplifier 14. In this way, the efficiency of the overall circuit can be improved.

[0031] The power amplifier circuit utilizes a Doherty power amplifier, comprising two amplifier circuits connected via the two outputs of a power divider 12: a main power amplifier 14 (carrier power amplifier) ​​and an auxiliary power amplifier 15 (peak power amplifier), also known as a Doherty power amplifier circuit. When the RF input power is less than a preset value, the Doherty power amplifier circuit operates in low-signal mode, with only the main power amplifier 14 operating. When the RF input power exceeds the preset value, the signal power reaches a certain threshold, and the auxiliary power amplifier 15 begins operating. This improves the overall efficiency of the power amplifier circuit, enabling the Doherty power amplifier to maintain high-efficiency output under varying signal strengths.

[0032] The power divider 12 is used to divide the input signal (RF input power) into two signals according to a certain power division ratio and phase relationship. The power divider 12 is the basis of the dual-path Doherty power amplifier circuit, which ensures that the signal can be evenly distributed to the two amplifier circuits of the main power amplifier 14 and the auxiliary power amplifier 15.

[0033] In the above embodiment, the active dynamic bias circuit 10 acts on the power divider 12 and the auxiliary power amplifier 15, respectively, by configuring a first voltage-dividing branch 134 and a second voltage-dividing branch 135 connected in parallel. The switch element 131 in the first voltage-dividing branch 134 and the second voltage-dividing branch 135 is controlled by the first control voltage Vctrl1, the second control voltage Vctrl2, and the RF input power. Thus, in combination with the operating characteristics of the switch element 131 and the settings of the first control voltage Vctrl1 and the second control voltage Vctrl2, when the Doherty power amplifier circuit is in the linear region, the first voltage-dividing branch 134 and the second voltage-dividing branch 135 are both disconnected. Accordingly, the power divider 12 is controlled to merge its ports within the small signal range, thereby reducing insertion loss. Furthermore, the auxiliary power amplifier 15 is controlled to operate in a very deep Class C mode, thereby improving the overall gain of the Doherty power amplifier circuit.

[0034] In some embodiments, the control switch SW1 is a field-effect transistor (FET), the gate of which is connected to the first voltage-dividing branch 134, and the source and drain of which are respectively connected to the two outputs of the power divider 12. The FET is a depletion-type FET, and the first voltage-dividing branch 134 is connected to the gate of the FET, providing a gate bias voltage to the FET to control the FET to be turned on or off, thereby correspondingly controlling the two outputs of the power divider 12 to be combined into one or to maintain two outputs, thereby improving the gain of the Doherty amplifier circuit in the linear region.

[0035] The first voltage-dividing branch 134 and the second voltage-dividing branch 135 are designed to provide a negative voltage divider when in the on state and a voltage divider voltage that is elevated relative to the voltage value before switching to the on state, respectively. In some embodiments, the first voltage-dividing branch 134 includes a first transistor D1 and a first voltage-dividing resistor R1 connected in series between the first control voltage Vctrl1 and the electrode ground; the second voltage-dividing branch 135 includes a second voltage-dividing resistor R2 and a second transistor D2 connected in series between the first control voltage Vctrl1 and the electrode ground; a first electrical node between the first transistor D1 and the first voltage-dividing resistor R1 is connected to the control terminal 133 of the control switch SW1; and a second electrical node between the second voltage-dividing resistor R2 and the second transistor D2 is connected to the gate of the auxiliary power amplifier 15. The first transistor D1 and the second transistor D2 are both field-effect transistors. In an optional specific example, both are depletion-type field-effect transistors, such as gallium nitride high-electron-mobility transistors. In the first voltage-dividing branch 134, the first voltage-dividing resistor R1 is connected between the first transistor D1 and the electrode ground. Thus, when the first voltage-dividing branch 134 is open, the voltage at the upper end of the first voltage-dividing resistor R1 is 0V, and the voltage of the control terminal 133 provided by the first voltage-dividing branch 134 to the control switch tube SW1 in the switch circuit 136 is 0V. When the first voltage-dividing branch 134 is open, based on the path relationship formed by the connection between the positive and negative poles of the first control voltage Vctrl1 and the first transistor D1 and the first voltage-dividing resistor R1, the voltage at the upper end of the first voltage-dividing resistor R1 is a negative voltage, and the voltage of the control terminal 133 provided by the first voltage-dividing branch 134 to the control switch tube SW1 in the switch circuit 136 is a negative voltage after voltage division. The difference is that in the second voltage-dividing branch 135, the second voltage-dividing resistor R2 is connected between the first control voltage Vctrl1 and the second transistor D2. In this way, when the second voltage-dividing branch 135 is in an open circuit, based on the path relationship formed by the positive and negative electrodes of the first control voltage Vctrl1 and the second transistor D2 and the second voltage-dividing resistor R2, the voltage at the lower end of the second voltage-dividing resistor R2 is less than the first control voltage Vctrl1. At this time, the second voltage-dividing branch 135 can provide a gate bias voltage close to but less than the first control voltage Vctrl1 to the auxiliary power amplifier 15, so that the auxiliary power amplifier 15 can operate in a very deep Class C state, so that it will not It affects the matching state of the main power amplifier 14 and improves the overall circuit efficiency of the power amplifier circuit at this time. When the second voltage-dividing branch 135 is in the passage, the voltage at the lower end of the second voltage-dividing resistor R2 is the voltage after voltage division, and the gate bias voltage provided by the second voltage-dividing branch 135 to the auxiliary power amplifier 15 is the voltage after voltage division, which is elevated relative to the voltage before voltage division. Similarly, the setting of the first control voltage Vctrl1, the second control voltage Vctrl2 and the second voltage-dividing resistor R2 can be used to change the size of the voltage elevation value after the second voltage-dividing branch 135 is turned on, so that the auxiliary power amplifier 15 can operate in Class AB, thereby improving the power and gain of the power amplifier circuit at this time.

[0036] In some embodiments, the switch circuit 136 further includes a rectifier diode connected between the first electrical node and the control terminal 133. The rectifier diodes include a first rectifier diode Do1 and a second rectifier diode Do2 connected in series to the control terminal 133 of the control switch SW1. The switch circuit 136 further includes a voltage-equalizing resistor R4 connected in parallel with the first rectifier diode Do1 and the second rectifier diode Do2. The first rectifier diode Do1 and the second rectifier diode Do2 are connected in series to the gate of the control switch SW1 for rectification. The rectifier diodes utilize their unidirectional conduction characteristics to achieve voltage stabilization and filtering, thereby rapidly lowering the gate voltage of the control switch SW1 to more quickly and accurately achieve state switching control of the control switch SW1.

[0037] Optionally, the first transistor D1 and the second transistor D2 are connected to a common gate and are both connected to the input of the main power amplifier 14. A second control voltage Vctrl2 is connected to the gates of the first transistor D1 and the second transistor D2, providing a gate voltage to the first transistor D1 and the second transistor D2. The first transistor D1 and the second transistor D2 are connected to a common gate and are connected to the second control voltage Vctrl2. The node between the second control voltage Vctrl2, the first voltage divider branch 134, and the second voltage divider branch 135 is connected to the input side of the main power amplifier 14. In this way, the dynamic bias circuit is connected to the input side of the main power amplifier 14 to intercept the power signal to achieve the purpose of turning on and controlling the first transistor D1 and the second transistor D2. Secondly, the second control voltage Vctrl2 provides a voltage that allows the first transistor D1 and the second transistor D2 to operate in different operating states. It should be noted that the specific values ​​of the first control voltage Vctrl1 and the second control voltage Vctrl2 can be specifically determined based on the setting method of each voltage-dividing branch in the aforementioned embodiment, the conduction conditions of each voltage-dividing branch, and the technical teachings for adjusting the gate bias of the switching circuit 136 and the auxiliary power amplifier 15 that each voltage-dividing branch needs to form when it is turned on. This application does not make any specific limitations on it.

[0038] Optionally, when the RF input power is less than a preset value, both the first voltage-dividing branch 134 and the second voltage-dividing branch 135 are open, controlling the switch SW1 to close and merging the two outputs of the power divider 12. The first control voltage Vctrl1 provides a gate bias to the auxiliary power amplifier 15 via the second voltage-dividing resistor R2, so that the auxiliary power amplifier 15 operates in Class C. In this way, when the power amplifier circuit is in the small signal range, the auxiliary power amplifier 15 operates in Class C, with the main power amplifier 14 primarily responsible for providing higher amplification gain and higher efficiency within the low-power input signal range. At this time, the output of the first voltage-dividing branch 134 can be used to control the merging of the two ports of the power divider 12, thereby eliminating the insertion loss of the power divider 12 and improving the gain of the overall circuit.

[0039] Optionally, when the RF input power is greater than a preset value, the first voltage divider branch 134 and the second voltage divider branch 135 are both open; the first voltage divider branch 134 provides a negative voltage to the control switch tube SW1, the control switch tube SW1 is disconnected, and the two outputs of the power divider 12 are respectively connected to the main power amplifier 14 and the auxiliary power amplifier 15. In this embodiment, the active dynamic bias circuit 10 uses a two-way amplifier circuit, a main power amplifier 14 and an auxiliary power amplifier 15. Within the small signal range, the main power amplifier 14 mainly provides higher amplification gain and higher efficiency. At this time, the two outputs of the power divider 12 are combined into one. Through the design of the active dynamic bias circuit, as the RF input power increases, the first voltage divider branch 134 and the second voltage divider branch 135 can be switched to a pass state, and the power divider 12 returns to a normal working state. At the same time, the second voltage divider branch 135 provides a relatively raised gate bias to the auxiliary power amplifier 15, so that the auxiliary power amplifier 15 can operate in Class AB. By utilizing the advantages of Class A and Class B power amplifiers, the auxiliary power amplifier 15 can assist the main power amplifier 14 to provide additional power gain, thereby effectively improving the power and gain of the overall circuit of the Doherty power amplifier.

[0040] In some embodiments, the second control voltage Vctrl2 is connected to the input terminal of the main power amplifier 14 via a DC blocking capacitor C1. The provision of the DC blocking capacitor C1 can implement frequency selection of the intercepted power at the connection to the main power amplifier 14. Optionally, a first filter capacitor C2 is connected to the connection line between the first voltage dividing branch 134 and the control terminal 133 of the control switch SW1, and a second filter capacitor C3 is connected to the connection line between the second voltage dividing branch 135 and the gate of the auxiliary power amplifier 15. These capacitors are respectively used to improve the quality and stability of the voltage at the control terminal 133 output by the first voltage dividing branch 134 to the control switch SW1, and the bias voltage output by the second voltage dividing branch 135 to the gate of the auxiliary power amplifier 15.

[0041] See also Figure 3In another aspect, an embodiment of the present application further provides a Doherty power amplifier circuit, comprising a main power amplifier 14, an auxiliary power amplifier 15, and an active dynamic bias circuit 10 according to any embodiment of the present application, wherein the active dynamic bias circuit 10 is connected to the input side of the main power amplifier 14. Specifically, the active dynamic bias circuit 10 is connected to the input side of the main power amplifier 14. Specifically, a bias switching circuit 13 can be configured to intercept the power signal at the input side of the main power amplifier 14. Combined with the settings of the first control voltage Vctrl1 and the second control voltage Vctrl2, the first transistor D1 and the second transistor D2 are turned on as the RF input power increases, allowing the first voltage divider branch 134 and the second voltage divider branch 135 to switch to a conductive state. At this time, the bias voltage of the gate of the auxiliary power amplifier 15 is raised to a preset value by the active dynamic bias circuit 10, and the auxiliary power amplifier 15 is biased to operate in Class AB.

[0042] The Doherty power amplifier circuit further includes a power divider 12; the two outputs of the power divider 12 are connected to the input of the main power amplifier 14 and the input of the auxiliary power amplifier 15, respectively. The active dynamic bias circuit 10 is connected to the input side of the main power amplifier 14, which may include the following situations: the control end of the switch element 131 is connected between the power divider 12 and the input of the main power amplifier 14; or the control end of the switch element 131 is connected to the input of the power divider 12; or the control end of the switch element 131 is connected to the pre-stage driver of the power divider 12. In this embodiment, the control end of the switch element 131 refers to the gate of the transistor in the first voltage divider branch 134 and the second voltage divider branch 135. By intercepting the power signal on the input side of the main power amplifier 14 and combining the settings of the first control voltage Vctrl1 and the second control voltage Vctrl2, the first transistor D1 and the second transistor D2 are turned on as the RF input power increases, switching the first voltage divider branch 134 and the second voltage divider branch 135 to a conductive state.

[0043] In an optional specific example, the power amplifier circuit is a Doherty power amplifier circuit, which adopts a Doherty power amplifier. Two control voltages Vctrl1 and Vctrl2 are used to provide voltages for controlling the first transistor D1 and the second transistor D2 to operate in class A / B / AB. When the Doherty power amplifier operates in the linear region, the first transistor D1 and the second transistor D2 are not turned on. At this time, the voltage divider branch where the first transistor D1 is located provides 0V to the control switch tube SW1, the control switch tube SW1 is turned on, the two ports of the power divider 12 are merged, and the 3dB insertion loss of the power divider 12 is eliminated. The voltage divider branch where the second transistor D2 is located provides a gate bias voltage less than the control voltage Vctrl1 to the auxiliary power amplifier 15. The auxiliary power amplifier 15 operates in an extremely deep class C and will not affect the matching state of the main power amplifier 15, thereby improving the gain and efficiency of the Doherty power amplifier circuit during fallback. As the RF input power increases, the first transistor D1 and the second transistor D2 are turned on, and the voltage divider branches where they are located form paths respectively. The voltage divider branch where the first transistor D1 is located provides a voltage to the control switch tube SW1 from 0V to a negative voltage, and the control switch tube SW1 is closed. The power divider 12 returns to the normal working state of the two ports output respectively. The voltage divider branch where the second transistor D2 is located provides an increased gate bias voltage to the auxiliary power amplifier 15. The auxiliary power amplifier 15 operates in Class AB, thereby improving the gain and efficiency of the Doherty power amplifier circuit in the saturation region. In this way, the embodiment of the present application introduces an active dynamic bias circuit to act on the power divider 12 and the auxiliary power amplifier 15 at the same time, thereby increasing the gain and efficiency of the Doherty power amplifier circuit in the linear region and the saturation region.

[0044] See also Figure 4 The present application also provides a Doherty power amplifier module, which includes a chip 21 and a package substrate 22. The chip 21 or the package substrate 22 may be provided with a Doherty power amplifier circuit according to an embodiment of the present application. The Doherty power amplifier circuit may be integrated within the chip 21 or the package substrate 22. The Doherty power amplifier module may be any type of radio frequency power amplifier product.

[0045] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0046] The above are only specific embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. An active dynamic bias circuit for a Doherty power amplifier, characterized in that: include: a first control voltage; a bias switching circuit comprising a voltage dividing circuit connected to the first control voltage, the voltage dividing circuit comprising a switching element and a voltage dividing element connected in series; a second control voltage connected to the control terminal of the switch element; A switching circuit, comprising a control switch connected between two outputs of the power divider; The switch element is controlled by the first control voltage, the second control voltage, and the radio frequency input power at the input side of the main power amplifier of the Doherty power amplifier. The voltage divider circuit includes a voltage divider output terminal connected to the gate of the auxiliary power amplifier of the Doherty power amplifier. When the radio frequency input power is greater than a preset value, the switch element is closed, thereby forming a path for the voltage divider circuit. The voltage divider circuit provides a gate bias voltage to the auxiliary power amplifier, so that the auxiliary power amplifier operates in class AB. In which, the voltage divider circuit includes a first voltage divider branch and a second voltage divider branch connected in parallel, the first voltage divider branch provides a switch control voltage to the control switch tube, and the second voltage divider branch provides a gate bias voltage to the auxiliary power amplifier; the first voltage divider branch includes a first transistor and a first voltage divider resistor connected in series between the first control voltage and the electrode ground, and the second voltage divider branch includes a second voltage divider resistor and a second transistor connected in series between the first control voltage and the electrode ground; a first electrical node between the first transistor and the first voltage divider resistor is connected to the control end of the control switch tube; a second electrical node between the second voltage divider resistor and the second transistor is connected to the gate of the auxiliary power amplifier.

2. The active dynamic bias circuit according to claim 1, wherein: The control switch tube is a field effect tube, the gate of the field effect tube is connected to the first voltage dividing branch, and the source and drain are connected between the two outputs of the power divider.

3. The active dynamic bias circuit according to claim 1, wherein: The switch circuit further includes a rectifier diode connected between the first electrical node and the control terminal.

4. The active dynamic bias circuit according to claim 1, wherein: The first transistor and the second transistor are connected to a common gate and are both connected to the input end of the main power amplifier. The second control voltage is connected to the gates of the first transistor and the second transistor to provide gate voltage to the first transistor and the second transistor.

5. The active dynamic bias circuit according to claim 1, wherein: When the input power is less than the preset value, the first voltage dividing branch and the second voltage dividing branch are both disconnected, the control switch is closed, and the two outputs of the power divider are combined; The first control voltage provides a gate bias voltage to the auxiliary power amplifier through the second voltage-dividing resistor, so that the auxiliary power amplifier operates in Class C.

6. The active dynamic bias circuit according to claim 5, wherein: When the input power is greater than the preset value, the first voltage dividing branch and the second voltage dividing branch are both passages; The first voltage dividing branch provides a negative voltage to the control switch tube, the control switch tube is disconnected, and the two outputs of the power divider are connected to the main power amplifier and the auxiliary power amplifier respectively.

7. The active dynamic bias circuit according to claim 1, wherein: The second control voltage is connected to the input terminal of the main power amplifier through a DC blocking capacitor.

8. A Doherty power amplifier circuit, characterized in that: comprising a main power amplifier, an auxiliary power amplifier and an active dynamic bias circuit according to any one of claims 1 to 7; The active dynamic bias circuit is connected to the input side of the main power amplifier.

9. The Doherty power amplifier circuit according to claim 8, characterized in that: The power amplifier circuit also includes a power divider; The two outputs of the power splitter are connected to the input end of the main power amplifier and the input end of the auxiliary power amplifier respectively; The control end of the switch element is connected between the power divider and the input end of the main power amplifier.

10. A Doherty power amplifier module, characterized in that: It comprises a chip and a packaging substrate, wherein the chip or the packaging substrate is provided with the Doherty power amplifier circuit as claimed in claim 8 or 9.

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