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

Abstract

The embodiment of the invention provides a Doherty power amplifier circuit with a source dynamic bias circuit of a Doherty power amplifier and a module. The active dynamic bias circuit comprises a first control voltage, a second control voltage, a third control voltage and a fourth control voltage, a bias switching circuit including a voltage division circuit connected to the first control voltage, the voltage division circuit including a switching element and a voltage division element connected in series; the second control voltage is connected with the control end of the switching element; the switch element is controlled by a first control voltage, a second control voltage and radio frequency input power, the voltage division circuit comprises a voltage division output end connected with a grid electrode of the auxiliary power amplifier, when the input power is larger than a preset value, the switch element is closed to enable the voltage division circuit to form a closed circuit, and the voltage division circuit provides grid bias voltage for the auxiliary power amplifier; therefore, the auxiliary power amplifier works in the AB type. Therefore, the auxiliary power amplifier works in the class AB in a high-power input signal range, the advantages of the class A power amplifier and the class B power amplifier can be combined, and the power and the gain of the whole circuit are effectively improved.

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 of 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 more and more stringent. Therefore, high back-off efficiency power amplifiers, such as Doherty power amplifiers, are becoming more and more widely used.

[0003] Traditional Doherty power amplifiers have high back-off efficiency and can meet the current high peak-to-average ratio signal requirements in the communications field. However, this amplifier structure also has its own shortcomings. Since the Doherty power amplifier needs to use a power divider at the input to distribute power, this leads to a reduction in the linear gain of the Doherty power amplifier, thereby worsening the efficiency. After the auxiliary power amplifier is turned on, since the auxiliary power amplifier usually works in Class C and has a low gain, the gain of the overall 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 of 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 switch 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, including 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 within the high-power input signal range by overlapping the working state with the main power amplifier. 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 the Doherty power amplifier module provided in the above embodiments belong to 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, which will not be described in detail herein. 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 Schematic diagram of the circuit structure of an active dynamic bias circuit of a Doherty power amplifier in one embodiment.

[0017] Figure 3 FIG. 4 is a schematic diagram of a circuit structure of a Doherty power amplifier circuit in an embodiment.

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

[0019] Component Symbols:

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

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

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

[0023] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the 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 also be a central 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 a central element at the same time. The terms "vertical", "horizontal", "inside", "outside", "left", "right" and similar expressions used herein are only for the purpose of explanation in conjunction with the embodiments of the accompanying drawings and do not represent the only implementation method.

[0026] Please refer to Figure 1 and Figure 2An embodiment of the present application provides an active dynamic bias circuit 10 of 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 comprises a voltage divider circuit connected to the first control voltage Vctrl1, and the voltage divider circuit comprises 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 comprises a voltage divider output end 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 switch element 131 is closed to form a path for the voltage divider circuit, and 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 supplies respectively. The voltage divider circuit is connected to the first control voltage Vctrl1. When the voltage divider circuit forms a path, the first control voltage Vctrl1 provides voltage division. The second control voltage Vctrl2 is connected to the control end of the switch element 131, and provides the voltage divider circuit with a control voltage that can control the working 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, so that the switch element 131 is simultaneously controlled by the first control voltage Vctrl1, the second control voltage Vctrl2 and the RF input power of 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 is greater than a preset value, the switch element 131 is controlled to close so that the voltage divider circuit forms a path.

[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] The meaning of the power amplifier working in different working states of Class A / B / AB / C is that, in Class A, when there is no signal input, the transistors remain in the on state, the output amplifies the full wave of the signal, there is no crossover distortion, and it has the most ideal amplification linearity. The disadvantage is that there is still full current flowing in when there is no signal, the electrical energy is converted into heat energy, and the power loss is large. In Class B, when there is no signal input, the transistors are not turned on. When there is a signal, each pair of output tubes amplifies half of the waveform, and works in turn on and off to complete a full-wave amplification, but crossover distortion will occur when the output transistors rotate to form nonlinearity. In Class AB, when there is no signal, a small amount of current passes through the output transistor. When the signal is weak, it uses the Class A working mode to obtain the best linearity. When the signal increases to a certain level, it automatically switches to the Class B working mode to obtain higher efficiency. In Class C, the input signal is converted into a pulse width modulation (PWM) signal, and then amplified through the transistor. The disadvantage is that the distortion is high.

[0030] In some embodiments, the bias switching circuit 13 further includes a switch circuit 136, and the switch circuit 136 includes a control switch tube 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, the first voltage divider branch 134 provides a switch control voltage to the control switch tube SW1, and the second voltage divider branch 135 provides a gate bias voltage to the auxiliary power amplifier 15. Among them, the first voltage divider branch 134 and the second voltage divider branch 135 are connected in parallel. In a specific example, the control switch tube SW1 is a depletion type (normally open) device, a typical depletion type field effect transistor, which can be a gallium nitride high electron mobility transistor. When the first voltage divider branch 134 is in an open circuit state, the switch control voltage provided by the first voltage divider branch 134 to the control switch tube SW1 is 0V. At this time, the control switch tube 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, which can remove a certain amount of insertion loss of the power divider 12. The insertion loss of the power divider 12 refers to the loss of the signal when passing through the power divider 12, usually expressed in decibels (dB). This loss is due to the conversion of part of the signal energy into heat or other forms of energy loss when the signal is transmitted and distributed to multiple output ports inside the power divider 12, resulting in a weakening of the output signal strength. Taking a two-way output power divider as an example, in an ideal state, the power of any output is half of the input function, which is converted into a logarithmic understanding of 10*lg2=3dB less than the original. The combination 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 an 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. Using the setting of the first control voltage Vctrl1, at this time, the auxiliary power amplifier 15 works 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 at this time.

[0031] The power amplifier circuit adopts a Doherty power amplifier, including two amplifier circuits respectively connected through the two outputs of the power divider 12, namely 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 is in small signal operation, and only the main power amplifier 14 works; when the RF input power is greater than the preset value, the signal power reaches a certain threshold, and the auxiliary power amplifier 15 starts to work, thereby improving the overall efficiency of the power amplifier circuit, so that the Doherty power amplifier can maintain high-efficiency output under different 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-channel 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 through the setting of the first voltage-dividing branch 134 and the 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. In this way, combined with the working characteristics of the switch element 131 and the setting 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 in an open circuit, and the power divider 12 is controlled to merge ports within the small signal range to reduce insertion loss, and the auxiliary power amplifier 15 is controlled to work in a very deep Class C, thereby improving the overall gain of the Doherty power amplifier circuit.

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

[0035] The design of the first voltage-dividing branch 134 and the second voltage-dividing branch 135 respectively provides a negative voltage division when in the on state, and a voltage division voltage raised relative to the voltage value before switching to the on state. 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, and 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; the 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 tube SW1; the 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, and in an optional specific example, they are both depletion field effect transistors, such as gallium nitride high electron mobility transistors. Among them, in the first voltage-dividing branch 134, the first voltage-dividing resistor R1 is connected between the first transistor D1 and the electrode ground. In this way, when the first voltage-dividing branch 134 is in an open circuit, the voltage at the upper end of the first voltage-dividing resistor R1 is 0V, and the voltage of the control end 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 in a pass, based on the pass relationship formed by the connection between the positive and negative electrodes 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 end 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 the auxiliary power amplifier 15 with a gate bias voltage close to but less than the first control voltage Vctrl1, so that the auxiliary power amplifier 15 can work in a very deep C class, 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 first control voltage Vctrl1, the second control voltage Vctrl2 and the second voltage-dividing resistor R2 can be used to change 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 diode includes a first rectifier diode Do1 and a second rectifier diode Do2 connected in series to the control terminal 133 of the control switch tube SW1, and 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 tube SW1 for rectification. The rectifier diode can achieve voltage stabilization and filtering by using the unidirectional conduction characteristic, so that it can cooperate with the rapid reduction of the gate voltage of the control switch tube SW1 to achieve the state switching control of the control switch tube SW1 more quickly and accurately.

[0037] Optionally, the first transistor D1 and the second transistor D2 are connected to the same gate and are both connected to the input end of the main power amplifier 14, and the second control voltage Vctrl2 is connected to the gate of the first transistor D1 and the second transistor D2 to provide gate voltage to the first transistor D1 and the second transistor D2. The first transistor D1 and the second transistor D2 are connected to the same gate and are connected to the second control voltage Vctrl2, and the node connected between the second control voltage Vctrl2 and the first voltage dividing branch 134 and the second voltage dividing 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, a voltage is provided through the second control voltage Vctrl2 so that the first transistor D1 and the second transistor D2 can work in different working 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 teaching of adjusting the switching circuit 136 and the gate bias of 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, the first voltage-dividing branch 134 and the second voltage-dividing branch 135 are both open circuited, the control switch SW1 is closed, and the two outputs of the power divider 12 are merged; the first control voltage Vctrl1 provides a gate bias to the auxiliary power amplifier 15 through the second voltage-dividing resistor R2, so that the auxiliary power amplifier 15 works in class C. In this way, when the power amplifier circuit is in the small signal range, the auxiliary power amplifier 15 works in class C, and the main power amplifier 14 is mainly responsible for providing a higher amplification gain and a higher efficiency within the low-power input signal range. At this time, the output of the first voltage-dividing branch 134 can control the two ports of the power divider 12 to merge, so as to remove the insertion loss of the power divider 12 to improve the gain of the overall circuit.

[0039] Optionally, when the RF input power is greater than a preset value, the first voltage-dividing branch 134 and the second voltage-dividing branch 135 are both open; the first voltage-dividing 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 adopts a two-way amplifier circuit of a main power amplifier 14 and an auxiliary power amplifier 15. In the small signal range, the main power amplifier 14 mainly provides a higher amplification gain and a 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. The auxiliary power amplifier 15 combines the advantages of Class A and Class B power amplifiers, thereby assisting the main power amplifier 14 to provide additional power gain, 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 end of the main power amplifier 14 through the DC blocking capacitor C1. The setting of the DC blocking capacitor C1 can realize the frequency selection of the intercepted power at the connection to the main power amplifier 14. Optionally, the connection line between the first voltage dividing branch 134 and the control end 133 of the control switch tube SW1 is connected with a first filter capacitor C2, and the connection line between the second voltage dividing branch 135 and the gate of the auxiliary power amplifier 15 is connected with a second filter capacitor C3, which are respectively used to improve the quality and stability of the control end 133 voltage output by the corresponding first voltage dividing branch 134 to the control switch tube SW1, and the bias voltage output by the corresponding second voltage dividing branch 135 to the gate of the auxiliary power amplifier 15.

[0041] See also Figure 3On the other hand, the embodiment of the present application also provides a Doherty power amplifier circuit, including a main power amplifier 14, an auxiliary power amplifier 15 and an active dynamic bias circuit 10 of 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. 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 set to intercept the power signal of the input side of the main power amplifier 14, and the first control voltage Vctrl1 and the second control voltage Vctrl2 can be combined to achieve the purpose of turning on the first transistor D1 and the second transistor D2 as the RF input power increases, so that the first voltage dividing branch 134 and the second voltage dividing branch 135 can be switched to the on 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 work in class AB.

[0042] The Doherty power amplifier circuit further includes a power divider 12; two outputs of the power divider 12 are respectively connected to the input end of the main power amplifier 14 and the input end of the auxiliary power amplifier 15. 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 end of the main power amplifier 14; or, the control end of the switch element 131 is connected to the input end 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 setting 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, and the first voltage divider branch 134 and the second voltage divider branch 135 are switched to the on 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, and the control switch tube SW1 is turned on. The two ports of the power divider 12 are merged to remove the 3dB insertion loss of the power divider 12. 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 back-off. As the RF input power increases, the first transistor D1 and the second transistor D2 are turned on, and the voltage-dividing branches where they are located form paths respectively. The voltage-dividing branch where the first transistor D1 is located provides a voltage from 0V to a negative voltage to control the switch tube SW1, and the control switch tube SW1 is closed, and the power divider 12 returns to the normal working state where the two ports are output respectively, and the voltage-dividing branch where the second transistor D2 is located provides a raised gate bias to the auxiliary power amplifier 15, and the auxiliary power amplifier 15 works 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 On the other hand, 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 provided in an embodiment of the present application. The Doherty power amplifier circuit may be integrated in the chip 21 or the package substrate 22, and the Doherty power amplifier module may be various types of radio frequency power amplifier products.

[0045] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0046] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope 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 switch element and a voltage dividing element connected in series; A second control voltage connected to the control terminal of the switch element; 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.

2. The active dynamic bias circuit according to claim 1, characterized in that: The bias switching circuit also includes a switch circuit, and the switch circuit includes a control switch tube connected between two outputs of the power divider; The voltage-dividing circuit comprises a first voltage-dividing branch and a second voltage-dividing branch connected in parallel, the first voltage-dividing branch provides a switch control voltage to the control switch tube, and the second voltage-dividing branch provides a gate bias voltage to the auxiliary power amplifier.

3. The active dynamic bias circuit according to claim 2, characterized in that: 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.

4. The active dynamic bias circuit according to claim 2, characterized in that: The first voltage-dividing branch includes a first transistor and a first voltage-dividing resistor connected in series between the first control voltage and the electrode ground, and the second voltage-dividing branch includes a second voltage-dividing 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-dividing resistor is connected to a control terminal of the control switch tube; A second electrical node between the second voltage-dividing resistor and the second transistor is connected to the gate of the auxiliary power amplifier.

5. The active dynamic bias circuit according to claim 4, characterized in that: The switch circuit further includes a rectifier diode connected between the first electrical node and the control terminal; and / or, The first transistor and the second transistor are connected to a common gate and are both connected to an input terminal of a main power amplifier. The second control voltage is connected to the gates of the first transistor and the second transistor to provide a gate voltage to the first transistor and the second transistor.

6. The active dynamic bias circuit according to claim 4, characterized in that: When the input power is less than the preset value, the first voltage-dividing branch and the second voltage-dividing branch are both open, the control switch tube is closed, and the two outputs of the power amplifier 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.

7. The active dynamic bias circuit according to claim 6, characterized in that: When the input power is greater than the preset value, both the first voltage division branch and the second voltage division branch are 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 respectively connected to the main power amplifier and the auxiliary power amplifier.

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

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

10. The Doherty power amplifier circuit according to claim 9, characterized in that: The power amplifier circuit also includes a power divider; The two outputs of the power divider 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; or, the control end of the switch element is connected to the input end of the power amplifier; or, the control end of the switch element is connected to the pre-stage driver of the power amplifier.

11. 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 9 or 10.

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